In order to help readers stay up-to-date in the field, each issue of Progress in Photovoltaics will contain a list of recently published journal articles that are most relevant to its aims and scope. This list is drawn from an extremely wide range of journals, including IEEE Journal of Photovoltaics, Solar Energy Materials and Solar Cells, Renewable Energy, Renewable and Sustainable Energy Reviews, Journal of Applied Physics, and Applied Physics Letters. To assist readers, the list is separated into broad categories, but please note that these classifications are by no means strict. Also note that inclusion in the list is not an endorsement of a paper's quality. If you have any suggestions, please email Ziv Hameiri at ziv.hameiri@unsw.edu.au.
Liuyanfeng
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30 Sep 05:02
Hybrid tandem solar cells with depleted-heterojunction quantum dot and polymer bulk heterojunction subcells
Publication date: October 2015
Source:Nano Energy, Volume 17
Author(s): Taesoo Kim, Yangqin Gao, Hanlin Hu, Buyi Yan, Zhijun Ning, Lethy Krishnan Jagadamma, Kui Zhao, Ahmad R. Kirmani, Jessica Eid, Michael M. Adachi, Edward H. Sargent, Pierre M. Beaujuge, Aram Amassian
We investigate hybrid tandem solar cells that rely on the combination of solution-processed depleted-heterojunction colloidal quantum dot (CQD) and bulk heterojunction polymer:fullerene subcells. The hybrid tandem solar cell is monolithically integrated and electrically connected in series with a suitable p–n recombination layer that includes metal oxides and a conjugated polyelectrolyte. We discuss the monolithic integration of the subcells, taking into account solvent interactions with underlayers and associated constraints on the tandem architecture, and show that an adequate device configuration consists of a low bandgap CQD bottom cell and a high bandgap polymer:fullerene top cell. Once we optimize the recombination layer and individual subcells, the hybrid tandem device reaches a V OC of 1.3V, approaching the sum of the individual subcell voltages. An impressive fill factor of 70% is achieved, further confirming that the subcells are efficiently connected via an appropriate recombination layer.
Source:Nano Energy, Volume 17
Author(s): Taesoo Kim, Yangqin Gao, Hanlin Hu, Buyi Yan, Zhijun Ning, Lethy Krishnan Jagadamma, Kui Zhao, Ahmad R. Kirmani, Jessica Eid, Michael M. Adachi, Edward H. Sargent, Pierre M. Beaujuge, Aram Amassian
We investigate hybrid tandem solar cells that rely on the combination of solution-processed depleted-heterojunction colloidal quantum dot (CQD) and bulk heterojunction polymer:fullerene subcells. The hybrid tandem solar cell is monolithically integrated and electrically connected in series with a suitable p–n recombination layer that includes metal oxides and a conjugated polyelectrolyte. We discuss the monolithic integration of the subcells, taking into account solvent interactions with underlayers and associated constraints on the tandem architecture, and show that an adequate device configuration consists of a low bandgap CQD bottom cell and a high bandgap polymer:fullerene top cell. Once we optimize the recombination layer and individual subcells, the hybrid tandem device reaches a V OC of 1.3V, approaching the sum of the individual subcell voltages. An impressive fill factor of 70% is achieved, further confirming that the subcells are efficiently connected via an appropriate recombination layer.
Graphical abstract
24 Sep 02:21
Efficient screen printed perovskite solar cells based on mesoscopic TiO2/Al2O3/NiO/carbon architecture
Publication date: October 2015
Source:Nano Energy, Volume 17
Author(s): Kun Cao, Zhixiang Zuo, Jin Cui, Yan Shen, Thomas Moehl, Shaik M. Zakeeruddin, Michael Grätzel, Mingkui Wang
We present efficient perovskite solar cells using a mesoscopic TiO2/Al2O3/NiO/carbon structure as framework. The CH3NH3PbI3-based device with quadruple-layer architecture achieves a power conversion efficiency of 15.03% under AM 1.5G illumination. Detailed investigations show an increased charge collection and reduced charge recombination in this device structure compared to that without NiO interlayer. It is found that these perovskite solar cells exhibit good stability both in dark and under illumination.
Source:Nano Energy, Volume 17
Author(s): Kun Cao, Zhixiang Zuo, Jin Cui, Yan Shen, Thomas Moehl, Shaik M. Zakeeruddin, Michael Grätzel, Mingkui Wang
We present efficient perovskite solar cells using a mesoscopic TiO2/Al2O3/NiO/carbon structure as framework. The CH3NH3PbI3-based device with quadruple-layer architecture achieves a power conversion efficiency of 15.03% under AM 1.5G illumination. Detailed investigations show an increased charge collection and reduced charge recombination in this device structure compared to that without NiO interlayer. It is found that these perovskite solar cells exhibit good stability both in dark and under illumination.
Graphical abstract
21 Sep 06:35
Induced photodegradation of quinoxaline based copolymers for photovoltaic applications
Publication date: January 2016
Source:Solar Energy Materials and Solar Cells, Volume 144
Author(s): Desta Gedefaw, Marta Tessarolo, Mario Prosa, Margherita Bolognesi, Patrik Henriksson, Wenliu Zhuang, Mirko Seri, Michele Muccini, Mats R. Andersson
We report here the synthesis and characterization of a series of p-type copolymers, which combine a fluorinated quinoxaline (FQ) acceptor unit either with a differently substituted benzodithiophene (BDT) or an unsubstituted thieno[3,2-b]thiophene (TT). The effect of the structural modifications on the photochemical stability of the resulting films is investigated and then correlated with the photovoltaic performance and lifetime measurements of corresponding photovolatic devices. To this end, we firstly studied the intrinsic stability of each polymer film by monitoring the UV–vis absorption decay, under simulated sunlight, as a function of ageing time. Bulk heterojunction solar cells, based on these polymers as donor materials, were fabricated and tested. Beside the initial values, we monitored the photovoltaic performance during prolonged light soaking in order to evaluate and compare the photostability of more complex systems such as working solar cells.
Source:Solar Energy Materials and Solar Cells, Volume 144
Author(s): Desta Gedefaw, Marta Tessarolo, Mario Prosa, Margherita Bolognesi, Patrik Henriksson, Wenliu Zhuang, Mirko Seri, Michele Muccini, Mats R. Andersson
We report here the synthesis and characterization of a series of p-type copolymers, which combine a fluorinated quinoxaline (FQ) acceptor unit either with a differently substituted benzodithiophene (BDT) or an unsubstituted thieno[3,2-b]thiophene (TT). The effect of the structural modifications on the photochemical stability of the resulting films is investigated and then correlated with the photovoltaic performance and lifetime measurements of corresponding photovolatic devices. To this end, we firstly studied the intrinsic stability of each polymer film by monitoring the UV–vis absorption decay, under simulated sunlight, as a function of ageing time. Bulk heterojunction solar cells, based on these polymers as donor materials, were fabricated and tested. Beside the initial values, we monitored the photovoltaic performance during prolonged light soaking in order to evaluate and compare the photostability of more complex systems such as working solar cells.
17 Sep 04:58
Highly conductive PEDOT:PSS transparent electrode prepared by a post-spin-rinsing method for efficient ITO-free polymer solar cells
Publication date: January 2016
Source:Solar Energy Materials and Solar Cells, Volume 144
Author(s): Xiaoqin Zhang, Jiang Wu, Jiantai Wang, Jun Zhang, Qingqing Yang, Yingying Fu, Zhiyuan Xie
We have proposed a post-spin-rinsing method (PSRM) with polar organic solvent dimethyl sulfoxide (DMSO) to prepare highly conductive and transparent PEDOT:PSS films. The PSRM-prepared PEDOT:PSS film exhibits a conductivity of 1335Scm−1, much higher than 776Scm−1 of the PEDOT:PSS film prepared with the conventional pre-adding method (PAM). In contrast to the PAM, the PSRM with DMSO is more effective to remove the insulating PSS and push the PEDOT chains from coiled to a linear/extended-coil alignment with conformation change from a benzoid structure to a more conductive quinoid structure, leading to an enhanced conductivity of the PEDOT:PSS film. The highly conductive PEDOT:PSS film is used as transparent electrode to fabricate indium tin oxide-free polymer solar cells and a power conversion efficiency of 4.82% is achieved for polymer solar cells based on PCDTBT:PC71BM blend.
Source:Solar Energy Materials and Solar Cells, Volume 144
Author(s): Xiaoqin Zhang, Jiang Wu, Jiantai Wang, Jun Zhang, Qingqing Yang, Yingying Fu, Zhiyuan Xie
We have proposed a post-spin-rinsing method (PSRM) with polar organic solvent dimethyl sulfoxide (DMSO) to prepare highly conductive and transparent PEDOT:PSS films. The PSRM-prepared PEDOT:PSS film exhibits a conductivity of 1335Scm−1, much higher than 776Scm−1 of the PEDOT:PSS film prepared with the conventional pre-adding method (PAM). In contrast to the PAM, the PSRM with DMSO is more effective to remove the insulating PSS and push the PEDOT chains from coiled to a linear/extended-coil alignment with conformation change from a benzoid structure to a more conductive quinoid structure, leading to an enhanced conductivity of the PEDOT:PSS film. The highly conductive PEDOT:PSS film is used as transparent electrode to fabricate indium tin oxide-free polymer solar cells and a power conversion efficiency of 4.82% is achieved for polymer solar cells based on PCDTBT:PC71BM blend.
Graphical abstract
15 Sep 02:34
High efficiency arrays of polymer solar cells fabricated by spray-coating in air
by Yiwei Zhang, Jonathan Griffin, Nicholas W. Scarratt, Tao Wang, David G. Lidzey
Abstract
We present bulk heterojunction organic solar cells fabricated by spray-casting both the PEDOT:PSS hole-transport layer (HTL) and active PBDTTT-EFT:PC71BM layers in air. Devices were fabricated in a (6 × 6) array across a large-area substrate (25 cm2) with each pixel having an active area of 6.45 mm2. We show that the film uniformity and operational homogeneity of the devices are excellent. The champion device with spray cast active layer on spin cast PEDOT:PSS had an power conversion efficiency (PCE) of 8.75%, and the best device with spray cast active layer and PEDOT:PSS had a PCE of 8.06%. The impacts of air and light exposure of the active layer on device performance are investigated and found to be detrimental. Copyright © 2015 John Wiley & Sons, Ltd.
High efficiency arrays of polymer solar cells are fabricated by spray-coating the photoactive and/or PEDOT:PSS layers in air. Devices were fabricated in a 6 × 6 array across a 5 × 5 cm2 substrate with each pixel having an active area of 6.45 mm2. The champion device with spray cast active layer on spin cast PEDOT:PSS had a PCE of 8.75%, and the best device with spray cast active layer and PEDOT:PSS had a PCE of 8.06%.
15 Sep 02:33
Future development promise for plastic-based solar electricity
by Brian Azzopardi
Abstract
Plastic-based photovoltaic (PV) technology, also known as organic photovoltaic (OPV), has the development promise to be one of the third PV generation technologies, practically where sunlight reaches a surface area both indoors and outdoors. This paper presents the economic forecast for solar electricity using OPV technology based on a 1 kWp domestic system. With reference to OPV roll-to-roll manufacturing, the paper discusses lifetime, efficiency, and costs factors of this emerging PV technology. Taking an outlook of historic PV technology developments and reflect future anticipated technology developments, the future levelised electricity cost is calculated using system life cycle costing techniques. Grid parity at levelised electricity cost below 25 c/kWh may already be reached within 10 years' time, and the technology would have been widespread, assuming a typical southern Europe average solar irradiance of 1700 kWh/m2/year. The influence of solar irradiance and the way the module performs over long periods of time expecting various degradation levels is studied using sensitivity analysis. Eventually, the financial attractiveness to mature silicon-based PV technology may decline suddenly as financial support schemes such as the popular Feed-in-Tariffs dry out. This would give rise to other promising solutions that have already been proven to be less energy intensive and cheaper to produce but may require a different integration model than present technologies. This paper demonstrates that under no financial support schemes emerging PV technologies such as OPV will manage to attract business and further developments. Copyright © 2015 John Wiley & Sons, Ltd.
This paper presents the economic forecast for solar electricity using organic photovoltaic (OPV) technology based on a 1 kWp domestic system. Taking an outlook of historic PV technology developments and reflect future anticipated technology developments, the future levelised electricity cost is calculated using system life cycle costing techniques. Grid parity at levelised electricity cost below 25 c/kWh may already be reached within 10 years' time, and the technology would have been widespread, assuming a typical southern Europe average solar irradiance of 1700 kWh/m2/year. This paper demonstrates that under no financial support schemes, emerging PV technologies such as OPV will manage to attract business and further developments.
15 Sep 01:45
Perovskite as an effective Voc switcher for high efficiency polymer solar cells
Publication date: February 2016
Source:Nano Energy, Volume 20
Author(s): Yuliang Zhang, Wei Yu, Wei Qin, Zhou Yang, Dong Yang, Yedi Xing, Shengzhong (Frank) Liu, Can Li
In the perovskite/polymer based parallel-like tandem solar cell, the distinctive absorption spectra between the organic–inorganic halide perovskite absorber (CH3NH3PbI3 (MAPI)) and poly-(diketopyrrolopyrrole-terthiophene) (PDPP3T) polymer absorber make it possible to investigate the electronic properties of charge carriers generated in either the perovskite or PDPP3T layer separately. The current density–voltage (J–V) curves of the device are measured under the monochromatic LED irradiation at significantly different wavelengths to confirm the charge carrier generated in MAPI offer higher V oc . The voltage biased external quantum efficiency (EQE) measurement is employed to understand the charge transport mechanism in the system. The J–V curves and EQE data confirm that charge carriers generated by the photons absorbed in the perovskite layer or in PDPP3T behave independently. Compared with the bulk heterojunction structure, this parallel-like tandem structure increases V oc while reducing thermalization loss, providing a possibility to break the traditional Shockley–Queisser (S–Q) limit set for single junction devices.
Source:Nano Energy, Volume 20
Author(s): Yuliang Zhang, Wei Yu, Wei Qin, Zhou Yang, Dong Yang, Yedi Xing, Shengzhong (Frank) Liu, Can Li
In the perovskite/polymer based parallel-like tandem solar cell, the distinctive absorption spectra between the organic–inorganic halide perovskite absorber (CH3NH3PbI3 (MAPI)) and poly-(diketopyrrolopyrrole-terthiophene) (PDPP3T) polymer absorber make it possible to investigate the electronic properties of charge carriers generated in either the perovskite or PDPP3T layer separately. The current density–voltage (J–V) curves of the device are measured under the monochromatic LED irradiation at significantly different wavelengths to confirm the charge carrier generated in MAPI offer higher V oc . The voltage biased external quantum efficiency (EQE) measurement is employed to understand the charge transport mechanism in the system. The J–V curves and EQE data confirm that charge carriers generated by the photons absorbed in the perovskite layer or in PDPP3T behave independently. Compared with the bulk heterojunction structure, this parallel-like tandem structure increases V oc while reducing thermalization loss, providing a possibility to break the traditional Shockley–Queisser (S–Q) limit set for single junction devices.
Graphical abstract
15 Sep 01:42
Room temperature fabrication of CH3NH3PbBr3 by anti-solvent assisted crystallization approach for perovskite solar cells with fast response and small J–V hysteresis
Publication date: October 2015
Source:Nano Energy, Volume 17
Author(s): Xiaojia Zheng, Bo Chen, Congcong Wu, Shashank Priya
Anti-solvent assisted crystallization (ASAC) approach was used to synthesize crystalline CH3NH3PbBr3 thin films with uniform microstructures through accelerated crystallization process at room temperature. The influence of different solvents and various interval dropping time on the final morphology was investigated. Photovoltaic devices with TiO2/CH3NH3PbBr3/spiro-MeOTAD structure were fabricated using ASAC approach without any post-annealing process. The devices were found to exhibit fast photocurrent response and small J–V hysteresis due to the room temperature processing that minimizes the formation of surface electron traps and corresponding slow transient current. The ASAC-CH3NH3PbBr3 solar cells exhibited open circuit voltage of 1.42V with champion power conversion efficiency (PCE) of 8.29%, much higher than the devices fabricated without using anti-solvent approach having a Voc of 1.01V and PCE of 3.15%. Our results demonstrate that ASAC approach can provide high performance room temperature fabrication method for low-cost perovskite solar cells.
Source:Nano Energy, Volume 17
Author(s): Xiaojia Zheng, Bo Chen, Congcong Wu, Shashank Priya
Anti-solvent assisted crystallization (ASAC) approach was used to synthesize crystalline CH3NH3PbBr3 thin films with uniform microstructures through accelerated crystallization process at room temperature. The influence of different solvents and various interval dropping time on the final morphology was investigated. Photovoltaic devices with TiO2/CH3NH3PbBr3/spiro-MeOTAD structure were fabricated using ASAC approach without any post-annealing process. The devices were found to exhibit fast photocurrent response and small J–V hysteresis due to the room temperature processing that minimizes the formation of surface electron traps and corresponding slow transient current. The ASAC-CH3NH3PbBr3 solar cells exhibited open circuit voltage of 1.42V with champion power conversion efficiency (PCE) of 8.29%, much higher than the devices fabricated without using anti-solvent approach having a Voc of 1.01V and PCE of 3.15%. Our results demonstrate that ASAC approach can provide high performance room temperature fabrication method for low-cost perovskite solar cells.
Graphical abstract
25 May 11:19
Enhanced efficiency of organic and perovskite photovoltaics from shape-dependent broadband plasmonic effects of silver nanoplates
Publication date: September 2015
Source:Solar Energy Materials and Solar Cells, Volume 140
Author(s): Hsiang-Lin Hsu , Tzong-Yuan Juang , Chih-Ping Chen , Cheng-Ming Hsieh , Chun-Chen Yang , Cheng-Liang Huang , Ru-Jong Jeng
In this study, we systematically investigated the plasmonic effects of silver nanoplates (Ag NPLs) embedded in organic and perovskite (PVSK) photovoltaic (PV) cells. Optical properties of the Ag NPLs were manipulated by varying their sizes and shapes through controllable wet chemical processes. As the lengths of the edges of the Ag NPLs increased, their surface plasmon resonance bands broadened, with the maximum extinction wavelength extending to as far as 750nm. After embedding various types of Ag NPLs into the PEDOT:PSS [poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate] layer, the short-circuit photocurrent density increased by 7.6–17.5%, relative to that of the pre-optimized control PVs, with the power conversion efficiency (PCE) increasing by up to 13%. We obtained an optimized PCE of 8.5% for normal PVSK device under simulated AM 1.5G irradiation (100mWcm−2). After the incorporation of Ag NPLs, a much higher PCE of 9.6% was obtained. External quantum efficiencies were increased significantly as a result of the increased plasmonic scattering effect of Ag NPLs.
Source:Solar Energy Materials and Solar Cells, Volume 140
Author(s): Hsiang-Lin Hsu , Tzong-Yuan Juang , Chih-Ping Chen , Cheng-Ming Hsieh , Chun-Chen Yang , Cheng-Liang Huang , Ru-Jong Jeng
In this study, we systematically investigated the plasmonic effects of silver nanoplates (Ag NPLs) embedded in organic and perovskite (PVSK) photovoltaic (PV) cells. Optical properties of the Ag NPLs were manipulated by varying their sizes and shapes through controllable wet chemical processes. As the lengths of the edges of the Ag NPLs increased, their surface plasmon resonance bands broadened, with the maximum extinction wavelength extending to as far as 750nm. After embedding various types of Ag NPLs into the PEDOT:PSS [poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate] layer, the short-circuit photocurrent density increased by 7.6–17.5%, relative to that of the pre-optimized control PVs, with the power conversion efficiency (PCE) increasing by up to 13%. We obtained an optimized PCE of 8.5% for normal PVSK device under simulated AM 1.5G irradiation (100mWcm−2). After the incorporation of Ag NPLs, a much higher PCE of 9.6% was obtained. External quantum efficiencies were increased significantly as a result of the increased plasmonic scattering effect of Ag NPLs.
Graphical abstract
25 May 11:12
High-performance inverted PThTPTI:PC71BM solar cells
Publication date: July 2015
Source:Nano Energy, Volume 15
Author(s): Hui Li , Jiamin Cao , Qing Zhou , Liming Ding , Jizheng Wang
A highly efficient D–A conjugated polymer (PThTPTI) was applied in inverted organic solar cells. Optimized PThTPTI:PC71BM cells give an outstanding PCE as high as 9.20%, with V oc of 0.882V, J sc of 14.31mA/cm2, FF of 72.9%, and over 72% EQE in the range of 420–640nm. DIO (1,8-diiodooctane) effects on device performance are also systematically investigated. The result shows that the addition of DIO produces greatly improved nanoscale morphology of the blend film, which actually does not lead to significantly improved light absorption and build-in potential. Instead it leads to more efficient charge transfer, less carrier recombination, longer effective carrier lifetime and higher carrier mobility, which are the main contributors for the high efficiency.
Source:Nano Energy, Volume 15
Author(s): Hui Li , Jiamin Cao , Qing Zhou , Liming Ding , Jizheng Wang
A highly efficient D–A conjugated polymer (PThTPTI) was applied in inverted organic solar cells. Optimized PThTPTI:PC71BM cells give an outstanding PCE as high as 9.20%, with V oc of 0.882V, J sc of 14.31mA/cm2, FF of 72.9%, and over 72% EQE in the range of 420–640nm. DIO (1,8-diiodooctane) effects on device performance are also systematically investigated. The result shows that the addition of DIO produces greatly improved nanoscale morphology of the blend film, which actually does not lead to significantly improved light absorption and build-in potential. Instead it leads to more efficient charge transfer, less carrier recombination, longer effective carrier lifetime and higher carrier mobility, which are the main contributors for the high efficiency.
Graphical abstract
25 May 11:11
Few-layered graphene quantum dots as efficient hole-extraction layer for high-performance polymer solar cells
Publication date: July 2015
Source:Nano Energy, Volume 15
Author(s): Zicheng Ding , Zhen Hao , Bin Meng , Zhiyuan Xie , Jun Liu , Liming Dai
In this study, we demonstrate that few-layered graphene quantum dots (F-GQDs) can be used as hole-extraction layer (HEL) for high efficiency polymer solar cells (PSCs). As a new class of HEL material, graphene oxide (GO) is not suitable for polymer solar cells (PSCs) based on highly efficient donor polymers due to the relatively low work function and the poor film-forming property of GO. To circumvent these two problems, we develop F-GQDs with a small size of about 4nm and high content of periphery COOH groups. The small size of F-GQD ensures an excellent film-forming capability and the abundant COOH groups increase the work function of F-GQD to 5.26eV from 5.01eV of GO. As the result, when used as HEL in high efficiency PSC devices with PTB7:PC71BM or PCDTBT:PC71BM as the active layer, F-GQDs outperforms GO and the state-of-the-art HEL, PEDOT:PSS. These results demonstrate the great potential of F-GQD as efficient HELs to achieve high-performance PSCs.
Source:Nano Energy, Volume 15
Author(s): Zicheng Ding , Zhen Hao , Bin Meng , Zhiyuan Xie , Jun Liu , Liming Dai
In this study, we demonstrate that few-layered graphene quantum dots (F-GQDs) can be used as hole-extraction layer (HEL) for high efficiency polymer solar cells (PSCs). As a new class of HEL material, graphene oxide (GO) is not suitable for polymer solar cells (PSCs) based on highly efficient donor polymers due to the relatively low work function and the poor film-forming property of GO. To circumvent these two problems, we develop F-GQDs with a small size of about 4nm and high content of periphery COOH groups. The small size of F-GQD ensures an excellent film-forming capability and the abundant COOH groups increase the work function of F-GQD to 5.26eV from 5.01eV of GO. As the result, when used as HEL in high efficiency PSC devices with PTB7:PC71BM or PCDTBT:PC71BM as the active layer, F-GQDs outperforms GO and the state-of-the-art HEL, PEDOT:PSS. These results demonstrate the great potential of F-GQD as efficient HELs to achieve high-performance PSCs.
Graphical abstract
25 May 10:56
Temperature-assisted controlling morphology and charge transport property for highly efficient perovskite solar cells
Publication date: Available online 23 May 2015
Source:Nano Energy
Author(s): Lifeng Zhu , Jiangjian Shi , Songtao Lv , Yueyong Yang , Xin Xu , Yuzhuan Xu , Junyan Xiao , Huijue Wu , Yanhong Luo , Dongmei Li , Qingbo Meng
Reaction temperature as a key parameter has been introduced to manipulate the film deposition of the CH3NH3PbI3 absorber fabricated by the two-step solution deposition method. It is found that conversion time of dense CH3NH3PbI3 layer can be significantly reduced by raising reaction temperature. CH3NH3PbI3 crystal grain sizes increase with reaction temperature increasing, resulting in rougher surface. CH3NH3PbI3 films deposited at higher temperatures exhibit better charge transport ability, larger built-in heterojunction field and weaker charge recombination, leading to enhanced solar cell performance. By optimizing reaction temperatures, as high as 17.40% and 14.02% of power conversion efficiencies of the mesoscopic and planar perovskite solar cells have been achieved, respectively.
Source:Nano Energy
Author(s): Lifeng Zhu , Jiangjian Shi , Songtao Lv , Yueyong Yang , Xin Xu , Yuzhuan Xu , Junyan Xiao , Huijue Wu , Yanhong Luo , Dongmei Li , Qingbo Meng
Reaction temperature as a key parameter has been introduced to manipulate the film deposition of the CH3NH3PbI3 absorber fabricated by the two-step solution deposition method. It is found that conversion time of dense CH3NH3PbI3 layer can be significantly reduced by raising reaction temperature. CH3NH3PbI3 crystal grain sizes increase with reaction temperature increasing, resulting in rougher surface. CH3NH3PbI3 films deposited at higher temperatures exhibit better charge transport ability, larger built-in heterojunction field and weaker charge recombination, leading to enhanced solar cell performance. By optimizing reaction temperatures, as high as 17.40% and 14.02% of power conversion efficiencies of the mesoscopic and planar perovskite solar cells have been achieved, respectively.
Graphical abstract
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16 Mar 02:30
A nonionic surfactant simultaneously enhancing wetting property and electrical conductivity of PEDOT:PSS for vacuum-free organic solar cells
Publication date: June 2015
Source:Solar Energy Materials and Solar Cells, Volume 137
Author(s): Zaifang Li , Wei Meng , Jinhui Tong , Chen Zhao , Fei Qin , Fangyuan Jiang , Sixing Xiong , Sheng Zeng , Ling Xu , Bin Hu , Yinhua Zhou
In this work, we report a nonionic surfactant (polyethylene glycol 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol ether, PEG-TmDD) that can improve the wetting property of PEDOT:PSS aqueous solution on the organic photoactive layer and simultaneously enhance the electrical conductivity of PEDOT:PSS film up to 526S/cm. Furthermore, the conductivity enhancement is significantly dependent on the thermal annealing, which is contrary to the conductivity behavior of PEDOT:PSS film prepared from the formulation added with ethylene glycol (EG) where the conductivity is almost independent of the thermal annealing. The temperature dependence of the conductivity of PEDOT:PSS by PEG-TmDD is possibly ascribed to decomposition of PEG-TmDD into EG and TmDD during thermal annealing. With the high conductivity and good wetting on the active layer, PEDOT:PSS mixed with PEG-TmDD is used as the top electrode for organic solar cells. The cells exhibit a fill factor of 60% and a power conversion efficiency of 4.1% using poly(3-hexylthiophene):indene-C60 bis-adduct as the active layer. The results indicate that the new formulation of PEDOT:PSS mixed with PEG-TmDD is suitable for preparing a top electrode for vacuum-free organic solar cells.
Source:Solar Energy Materials and Solar Cells, Volume 137
Author(s): Zaifang Li , Wei Meng , Jinhui Tong , Chen Zhao , Fei Qin , Fangyuan Jiang , Sixing Xiong , Sheng Zeng , Ling Xu , Bin Hu , Yinhua Zhou
In this work, we report a nonionic surfactant (polyethylene glycol 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol ether, PEG-TmDD) that can improve the wetting property of PEDOT:PSS aqueous solution on the organic photoactive layer and simultaneously enhance the electrical conductivity of PEDOT:PSS film up to 526S/cm. Furthermore, the conductivity enhancement is significantly dependent on the thermal annealing, which is contrary to the conductivity behavior of PEDOT:PSS film prepared from the formulation added with ethylene glycol (EG) where the conductivity is almost independent of the thermal annealing. The temperature dependence of the conductivity of PEDOT:PSS by PEG-TmDD is possibly ascribed to decomposition of PEG-TmDD into EG and TmDD during thermal annealing. With the high conductivity and good wetting on the active layer, PEDOT:PSS mixed with PEG-TmDD is used as the top electrode for organic solar cells. The cells exhibit a fill factor of 60% and a power conversion efficiency of 4.1% using poly(3-hexylthiophene):indene-C60 bis-adduct as the active layer. The results indicate that the new formulation of PEDOT:PSS mixed with PEG-TmDD is suitable for preparing a top electrode for vacuum-free organic solar cells.
Graphical abstract
16 Mar 01:44
Improved open-circuit voltage of benzodithiophene based polymer solar cells using bulky terthiophene side group
Publication date: July 2015
Source:Solar Energy Materials and Solar Cells, Volume 138
Author(s): Qian Liu , Xichang Bao , Liangliang Han , Chuantao Gu , Meng Qiu , Zhengkun Du , Ruiying Sheng , Mingliang Sun , Renqiang Yang
Terthiophene, including one α–α and one branching α–β connection of the thiophene units, is introduced as benzodithiophene (BDT) side chain to build a novel two-dimensional (2D) conjugated BDT block. By copolymerizing this BDT block with three electron acceptors (DTTz (bis(thiophene-2-yl)-tetrazine), DPP (diketopyrrolopyrrole), DTffBT (4,7-bis(4-hexylthienyl)-5,6-difluoro-2,1,3-benzothiadiazole)) and one electron donor (TTT (2,5-Di(2-thienyl)thiophene)), four terthiophene side-chained benzodithiophene based copolymers were synthesized. Due to the difference in electron affinity among DTTz, DPP, DTffBT and TTT, these four polymers show different UV–vis absorption spectra and optical band gaps (1.3–2.0eV), while fortunately they all remain deep highest occupied molecular orbital (HOMO) energy levels (−5.3 to 5.6eV) which is very favorable to high open-circuit voltage (V oc) polymer solar cells (PSCs). By comparing the photovoltaic properties with polymers which have same backbone but do not have the bulky 2D side group in the literatures, our polymer solar cells devices show higher V oc. Especially for PQ3 (a copolymer of benzodithiophene and diketopyrrolopyrrole), the donor photon energy loss (E g–eV oc) is 0.51eV which is almost the lowest value achieved by the researchers. It can be concluded that: the bulky terthiophene side group helps to improve V oc of the PSCs devices. The overall performance of solar cells devices is correlated with the molecule conformation, polymer hole mobility and polymer/PCBM blend film morphology.
Source:Solar Energy Materials and Solar Cells, Volume 138
Author(s): Qian Liu , Xichang Bao , Liangliang Han , Chuantao Gu , Meng Qiu , Zhengkun Du , Ruiying Sheng , Mingliang Sun , Renqiang Yang
Terthiophene, including one α–α and one branching α–β connection of the thiophene units, is introduced as benzodithiophene (BDT) side chain to build a novel two-dimensional (2D) conjugated BDT block. By copolymerizing this BDT block with three electron acceptors (DTTz (bis(thiophene-2-yl)-tetrazine), DPP (diketopyrrolopyrrole), DTffBT (4,7-bis(4-hexylthienyl)-5,6-difluoro-2,1,3-benzothiadiazole)) and one electron donor (TTT (2,5-Di(2-thienyl)thiophene)), four terthiophene side-chained benzodithiophene based copolymers were synthesized. Due to the difference in electron affinity among DTTz, DPP, DTffBT and TTT, these four polymers show different UV–vis absorption spectra and optical band gaps (1.3–2.0eV), while fortunately they all remain deep highest occupied molecular orbital (HOMO) energy levels (−5.3 to 5.6eV) which is very favorable to high open-circuit voltage (V oc) polymer solar cells (PSCs). By comparing the photovoltaic properties with polymers which have same backbone but do not have the bulky 2D side group in the literatures, our polymer solar cells devices show higher V oc. Especially for PQ3 (a copolymer of benzodithiophene and diketopyrrolopyrrole), the donor photon energy loss (E g–eV oc) is 0.51eV which is almost the lowest value achieved by the researchers. It can be concluded that: the bulky terthiophene side group helps to improve V oc of the PSCs devices. The overall performance of solar cells devices is correlated with the molecule conformation, polymer hole mobility and polymer/PCBM blend film morphology.
Graphical abstract
16 Mar 01:41
New bioinspired hole injection/transport materials for highly efficient solution-processed phosphorescent organic light-emitting diodes
Publication date: April 2015
Source:Nano Energy, Volume 13
Author(s): Chih-Chia Cheng , Yu-Lin Chu , Feng-Chih Chang , Duu-Jong Lee , Ying-Chieh Yen , Jem-Kun Chen , Chih-Wei Chu , Zhong Xin
A new concept to supramolecular assembly of existed functional polymers, capable of forming network-like organizational clusters through multiple hydrogen-bonding interactions has been exploited. In this paper, a new adenine-based poly(triphenylamine-carbazole) (PTC-A) has been prepared which exhibits a high self-complementary ability in solution and solid states owing to the formation of adenine–adenine (A–A) pairs by induced hierarchical self-assembly. Comparing with uracil-substituted PTC sample (PTC-U), PTC-A presents a much higher thermal stability, electrochemical stability and solvent-resistance ability due to the formation of the more stable physically cross-linking structure. When the PTC-A is utilized as a hole injection/transport layer in a trilayer OLED device, a remarkable improvement in performance relative to the control PTC and PTC-U under similar experimental conditions has been achieved. Further comparison with a control device using a conventional PEDOT:PSS, the efficiency of the solution-processed phosphorescent PLED device with PTC-A is significantly higher than those of PTC-U and PEDOT:PSS-based devices. Thus, PTC-A represents the next-generation hole injection/transport material for high efficiency LED device and low-cost fabrication process.
Source:Nano Energy, Volume 13
Author(s): Chih-Chia Cheng , Yu-Lin Chu , Feng-Chih Chang , Duu-Jong Lee , Ying-Chieh Yen , Jem-Kun Chen , Chih-Wei Chu , Zhong Xin
A new concept to supramolecular assembly of existed functional polymers, capable of forming network-like organizational clusters through multiple hydrogen-bonding interactions has been exploited. In this paper, a new adenine-based poly(triphenylamine-carbazole) (PTC-A) has been prepared which exhibits a high self-complementary ability in solution and solid states owing to the formation of adenine–adenine (A–A) pairs by induced hierarchical self-assembly. Comparing with uracil-substituted PTC sample (PTC-U), PTC-A presents a much higher thermal stability, electrochemical stability and solvent-resistance ability due to the formation of the more stable physically cross-linking structure. When the PTC-A is utilized as a hole injection/transport layer in a trilayer OLED device, a remarkable improvement in performance relative to the control PTC and PTC-U under similar experimental conditions has been achieved. Further comparison with a control device using a conventional PEDOT:PSS, the efficiency of the solution-processed phosphorescent PLED device with PTC-A is significantly higher than those of PTC-U and PEDOT:PSS-based devices. Thus, PTC-A represents the next-generation hole injection/transport material for high efficiency LED device and low-cost fabrication process.
Graphical abstract
16 Mar 01:40
Efficiency improved for inverted polymer solar cells with electrostatically self-assembled BenMeIm-Cl ionic liquid layer as cathode interface layer
Publication date: April 2015
Source:Nano Energy, Volume 13
Author(s): Ping Fu , Linquan Huang , Wei Yu , Dong Yang , Guiji Liu , Lingyu Zhou , Jian Zhang , Can Li
The interlayer inserted between active layer and ITO has been a key issue for improving electron extraction in inverted polymer solar cells (IPSCs), while the ideal interlayer for IPSCs has not been well developed. In this work, we presented a spontaneous vertical phase separation (SVPS) self-assembled bilayers structure with BenMeIm-Cl ionic liquid (IL) interfacial bottom layer and a photoactive top layer via a single spin-coated step of BenMeIm-Cl IL and organic donor–acceptor composite and achieved a PCE as high as 8% based on IPSCs with PTB7 as the donor. The presence of BenMeIm-Cl IL reduces the work function of ITO and leads to a better energy-level matching for efficient charge-transfer. The driving force of SVPS self-assembled structure is from the relative surface energy difference between organic materials and BenMeIm-Cl ILs, together with their interactions with the substrates. This self-assembled process procedure pave the way to simplify the manufacturing of low-cost and large-area organic electronic devices.
Source:Nano Energy, Volume 13
Author(s): Ping Fu , Linquan Huang , Wei Yu , Dong Yang , Guiji Liu , Lingyu Zhou , Jian Zhang , Can Li
The interlayer inserted between active layer and ITO has been a key issue for improving electron extraction in inverted polymer solar cells (IPSCs), while the ideal interlayer for IPSCs has not been well developed. In this work, we presented a spontaneous vertical phase separation (SVPS) self-assembled bilayers structure with BenMeIm-Cl ionic liquid (IL) interfacial bottom layer and a photoactive top layer via a single spin-coated step of BenMeIm-Cl IL and organic donor–acceptor composite and achieved a PCE as high as 8% based on IPSCs with PTB7 as the donor. The presence of BenMeIm-Cl IL reduces the work function of ITO and leads to a better energy-level matching for efficient charge-transfer. The driving force of SVPS self-assembled structure is from the relative surface energy difference between organic materials and BenMeIm-Cl ILs, together with their interactions with the substrates. This self-assembled process procedure pave the way to simplify the manufacturing of low-cost and large-area organic electronic devices.
Graphical abstract
27 Jan 00:42
N-acyl-dithieno[3,2-b:2’,3’-d]pyrrole-based low bandgap copolymers affording improved open-circuit voltages and efficiencies in polymer solar cells
Publication date: May 2015
Source:Solar Energy Materials and Solar Cells, Volume 136
Author(s): Jurgen Kesters , Pieter Verstappen , Wouter Vanormelingen , Jeroen Drijkoningen , Tim Vangerven , Dries Devisscher , Lidia Marin , Benoît Champagne , Jean Manca , Laurence Lutsen , Dirk Vanderzande , Wouter Maes
Three distinct low bandgap copolymers are synthesized by the combination of N-(2′-propylpentanoyl)dithieno[3,2-b:2′,3′-d]pyrrole (DTP) and (fluorinated) 2,3-bis[5′-(2”-ethylhexyl)thiophen-2′-yl]quinoxaline (Qx) and these PDTPQx derivatives are investigated as electron donor materials in bulk heterojunction polymer solar cells. Due to the DTP N-acylation and the introduction of the Qx units, both the open-circuit voltage (Voc) and the short-circuit current density (Jsc) increase compared to previous devices based on DTP-type donor polymers. Organic solar cells with an average Voc of 0.67V, a Jsc of 12.57mA/cm² and a fill factor of 0.54 are obtained, affording a power conversion efficiency of 4.53% (4.81% for the top-performing device), a record value for (N-acyl-)DTP-based polymer solar cells devoid of special interlayer materials. Despite further enhancement of the Voc, the solar cell efficiency declines for the fluorinated PDTPQx copolymers because of the inability to achieve a finely intermixed bulk heterojunction blend nanomorphology.
Source:Solar Energy Materials and Solar Cells, Volume 136
Author(s): Jurgen Kesters , Pieter Verstappen , Wouter Vanormelingen , Jeroen Drijkoningen , Tim Vangerven , Dries Devisscher , Lidia Marin , Benoît Champagne , Jean Manca , Laurence Lutsen , Dirk Vanderzande , Wouter Maes
Three distinct low bandgap copolymers are synthesized by the combination of N-(2′-propylpentanoyl)dithieno[3,2-b:2′,3′-d]pyrrole (DTP) and (fluorinated) 2,3-bis[5′-(2”-ethylhexyl)thiophen-2′-yl]quinoxaline (Qx) and these PDTPQx derivatives are investigated as electron donor materials in bulk heterojunction polymer solar cells. Due to the DTP N-acylation and the introduction of the Qx units, both the open-circuit voltage (Voc) and the short-circuit current density (Jsc) increase compared to previous devices based on DTP-type donor polymers. Organic solar cells with an average Voc of 0.67V, a Jsc of 12.57mA/cm² and a fill factor of 0.54 are obtained, affording a power conversion efficiency of 4.53% (4.81% for the top-performing device), a record value for (N-acyl-)DTP-based polymer solar cells devoid of special interlayer materials. Despite further enhancement of the Voc, the solar cell efficiency declines for the fluorinated PDTPQx copolymers because of the inability to achieve a finely intermixed bulk heterojunction blend nanomorphology.
Graphical abstract
22 Jan 03:25
Quantifying interface states and bulk defects in high-efficiency solution-processed small-molecule solar cells by impedance and capacitance characteristics
by Viktor V. Brus, Aung Ko Ko Kyaw, Pavlo D. Maryanchuk, Jie Zhang
Abstract
The AC properties of high-efficiency (η = 8.01% under standard 100 mW/cm2 AM1.5 illumination) small-molecule bulk heterojunction (SM BHJ) solar cells (p-DTS(FBTTh2)2/PC70BM) at different DC biases and frequencies of small amplitude (±10 mV) AC signal in the dark at room temperature were investigated in details. We showed the presence of interface states at the heterojunction interface and determined their parameters from the analysis of spectral distributions of real and imaginary components of the measured impedance. The dielectric constant of BHJ εBHJ = 2.9 was determined from the geometrical capacitance of totally depleted BHJ layer. We explained quantitatively the effect of interface states and series resistance on the measured C-V characteristics of the SM BHJ solar cells at both low and high frequencies. The quantitative value of the density of defect states in the bulk N = 1.05 × 1016 cm−3 was determined from the high frequency C-V characteristic corrected by the effect of the series resistance. Copyright © 2015 John Wiley & Sons, Ltd.
The AC properties of high-efficiency (η = 8.01%) small-molecule bulk heterojunction solar cells (p-DTS(FBTTh2)2/PC70BM) at different DC biases and frequencies of small amplitude AC signal in the dark at room temperature were investigated. We showed the presence of interface states at the heterojunction interface and determined their parameters from the analysis of the measured impedance spectroscopy. We also quantitatively determined the density of defect states in the bulk (N = 1.05 × 1016 cm−3) from the high frequency C-V characteristic.
21 Jan 12:04
A new strategy for fabricating organic photovoltaic devices with stable D/A double-channel network to enhance performance using self-assembling all-conjugated diblock copolymer
Publication date: April 2015
Source:Nano Energy, Volume 13
Author(s): Yi-Huan Lee , Wei-Chih Chen , Chi-Ju Chiang , Kuo-Chang Kau , Wei-Shin Liou , Yu-Ping Lee , Leeyih Wang , Chi-An Dai
In this study, we demonstrate the cooperative self-assembly of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) and an all-conjugated poly(2,5-dihexyloxy-p-phenylene)-b-poly(3-hexylthiophene) (PPP-P3HT) block copolymer to yield organic photovoltaic devices with enhanced solar cell performance and long-term stability. By a combination of TEM, GISAXS and GIWAXS structural investigations, it was found that a PPP-P3HT/PCBM hybrid film adopts a donor/acceptor (D/A) double-channel network (DCN) structure via simple spin-coating by self-organizing highly ordered and long-ranged crystalline P3HT nanofibrils as a hole-transporting channel, and the surrounding amorphous PPP domain with PCBM confined and dispersed within as the other electron-transporting channel. As a consequence of the structural development, the block copolymer hybrid solar cells could afford significant improvements in the charge transporting property and enhanced exciton separation, leading to a substantial improvement in the power conversion efficiency (PCE) of the resulting device. The photovoltaic devices with the DCN structure gave a high average PCE of 3.43% as compared to only 2.77% from a conventional P3HT/PCBM bulk heterojuction (BHJ) solar cell. Notably, the DCN solar cell showed significant improvements in thermal stability over the P3HT/PCBM BHJ solar cell in accelerated testing experiments. This enhancement is believed to be due to the nanoconfinement effect of the double-channel structure on the PCBM molecules, thereby averting PCBM aggregation problems typically occurring in BHJ devices. These results show promise for the practical usage of all-conjugated block copolymers with different main chain moieties towards the fabrication of organic photovoltaic devices with superior stability and competitive optoelectronic properties.
Source:Nano Energy, Volume 13
Author(s): Yi-Huan Lee , Wei-Chih Chen , Chi-Ju Chiang , Kuo-Chang Kau , Wei-Shin Liou , Yu-Ping Lee , Leeyih Wang , Chi-An Dai
In this study, we demonstrate the cooperative self-assembly of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) and an all-conjugated poly(2,5-dihexyloxy-p-phenylene)-b-poly(3-hexylthiophene) (PPP-P3HT) block copolymer to yield organic photovoltaic devices with enhanced solar cell performance and long-term stability. By a combination of TEM, GISAXS and GIWAXS structural investigations, it was found that a PPP-P3HT/PCBM hybrid film adopts a donor/acceptor (D/A) double-channel network (DCN) structure via simple spin-coating by self-organizing highly ordered and long-ranged crystalline P3HT nanofibrils as a hole-transporting channel, and the surrounding amorphous PPP domain with PCBM confined and dispersed within as the other electron-transporting channel. As a consequence of the structural development, the block copolymer hybrid solar cells could afford significant improvements in the charge transporting property and enhanced exciton separation, leading to a substantial improvement in the power conversion efficiency (PCE) of the resulting device. The photovoltaic devices with the DCN structure gave a high average PCE of 3.43% as compared to only 2.77% from a conventional P3HT/PCBM bulk heterojuction (BHJ) solar cell. Notably, the DCN solar cell showed significant improvements in thermal stability over the P3HT/PCBM BHJ solar cell in accelerated testing experiments. This enhancement is believed to be due to the nanoconfinement effect of the double-channel structure on the PCBM molecules, thereby averting PCBM aggregation problems typically occurring in BHJ devices. These results show promise for the practical usage of all-conjugated block copolymers with different main chain moieties towards the fabrication of organic photovoltaic devices with superior stability and competitive optoelectronic properties.
Graphical abstract
15 Jan 00:53
Highly efficient and stable planar perovskite solar cells with reduced graphene oxide nanosheets as electrode interlayer
Publication date: March 2015
Source:Nano Energy, Volume 12
Author(s): Jun-Seok Yeo , Rira Kang , Sehyun Lee , Ye-Jin Jeon , NoSoung Myoung , Chang-Lyoul Lee , Dong-Yu Kim , Jin-Mun Yun , You-Hyun Seo , Seok-Soon Kim , Seok-In Na
We demonstrate a simple solution and room-temperature processed reduced graphene oxide (RGO) as a novel hole-transporting material (HTM) to guarantee highly efficient and highly stable CH3NH3PbI3 perovskite solar cells (PeSCs). The effects of RGO HTM are systemically investigated in terms of PeSC efficiency, PeSC stability, morphology of perovskite film, recombination dynamics, and charge-transport through CH3NH3PbI3/HTM interface. The resultant PeSC with a planar configuration of glass/ITO/RGO/CH3NH3PbI3/PC61BM/bathocuproine (BCP)/Ag exhibits improved device efficiency (maximum PCE of 10.8%) with high reproducibility than those of the reference devices using conventional PEDOT:PSS and GO HTMs. Also, the RGO-based PeSCs show highly desirable device stability in comparison to the PEDOT:PSS PeSCs.
Source:Nano Energy, Volume 12
Author(s): Jun-Seok Yeo , Rira Kang , Sehyun Lee , Ye-Jin Jeon , NoSoung Myoung , Chang-Lyoul Lee , Dong-Yu Kim , Jin-Mun Yun , You-Hyun Seo , Seok-Soon Kim , Seok-In Na
We demonstrate a simple solution and room-temperature processed reduced graphene oxide (RGO) as a novel hole-transporting material (HTM) to guarantee highly efficient and highly stable CH3NH3PbI3 perovskite solar cells (PeSCs). The effects of RGO HTM are systemically investigated in terms of PeSC efficiency, PeSC stability, morphology of perovskite film, recombination dynamics, and charge-transport through CH3NH3PbI3/HTM interface. The resultant PeSC with a planar configuration of glass/ITO/RGO/CH3NH3PbI3/PC61BM/bathocuproine (BCP)/Ag exhibits improved device efficiency (maximum PCE of 10.8%) with high reproducibility than those of the reference devices using conventional PEDOT:PSS and GO HTMs. Also, the RGO-based PeSCs show highly desirable device stability in comparison to the PEDOT:PSS PeSCs.
Graphical abstract
09 Jan 01:57
Digital fabrication of organic solar cells by Inkjet printing using non-halogenated solvents
Publication date: March 2015
Source:Solar Energy Materials and Solar Cells, Volume 134
Author(s): T.M. Eggenhuisen , Y. Galagan , E.W.C. Coenen , W.P. Voorthuijzen , M.W.L. Slaats , S.A. Kommeren , S. Shanmuganam , M.J.J. Coenen , R. Andriessen , W.A. Groen
Inkjet printing offers versatility and flexibility for the sequential deposition of functional layers for the production of large area organic photovoltaics (OPV). Four layers of an OPV cell are inkjet printed, comprising an ITO-free semi-transparent front electrode (a metal current collecting grid, inkjet printed PEDOT:PSS and ZnO nanoparticle layers), and the photo-active layer combined with PEDOT:PSS as hole transport layer. To render the process R2R compatible, large area printing is performed using a 3.5cm wide printhead and non-halogenated ink formulations only. Similar performance is achieved for the inkjet printed cells as for cells with only spin coated layers and ITO. For the P3HT/PCBM bulk-heterojunction, a mixture of non-halogenated solvents ensured good solubility, proper printing behavior and a blend morphology that yields similar performance to a layer spin-coated from chlorinated solvents. The potential of inkjet printing for large area OPV was demonstrated by the fabrication of a module with 92cm2 active area, which showed an efficiency of 0.98%. Losses due to front and back electrode resistances are modeled and used to explain the recorded I-V curve. Combining these functional layers with inkjet printed electrodes lays out the roadmap toward fully roll-to-roll compatible digital fabrication of OPV.
Source:Solar Energy Materials and Solar Cells, Volume 134
Author(s): T.M. Eggenhuisen , Y. Galagan , E.W.C. Coenen , W.P. Voorthuijzen , M.W.L. Slaats , S.A. Kommeren , S. Shanmuganam , M.J.J. Coenen , R. Andriessen , W.A. Groen
Inkjet printing offers versatility and flexibility for the sequential deposition of functional layers for the production of large area organic photovoltaics (OPV). Four layers of an OPV cell are inkjet printed, comprising an ITO-free semi-transparent front electrode (a metal current collecting grid, inkjet printed PEDOT:PSS and ZnO nanoparticle layers), and the photo-active layer combined with PEDOT:PSS as hole transport layer. To render the process R2R compatible, large area printing is performed using a 3.5cm wide printhead and non-halogenated ink formulations only. Similar performance is achieved for the inkjet printed cells as for cells with only spin coated layers and ITO. For the P3HT/PCBM bulk-heterojunction, a mixture of non-halogenated solvents ensured good solubility, proper printing behavior and a blend morphology that yields similar performance to a layer spin-coated from chlorinated solvents. The potential of inkjet printing for large area OPV was demonstrated by the fabrication of a module with 92cm2 active area, which showed an efficiency of 0.98%. Losses due to front and back electrode resistances are modeled and used to explain the recorded I-V curve. Combining these functional layers with inkjet printed electrodes lays out the roadmap toward fully roll-to-roll compatible digital fabrication of OPV.
04 Jan 01:31
Solar cell efficiency tables (Version 45)
by Martin A. Green, Keith Emery, Yoshihiro Hishikawa, Wilhelm Warta, Ewan D. Dunlop
ABSTRACT
Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July 2014 are reviewed. Copyright © 2014 John Wiley & Sons, Ltd.
Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July 2014 are reviewed.
04 Jan 01:30
Repair of defects in photoactive layer of organic solar cells
Publication date: March 2015
Source:Solar Energy Materials and Solar Cells, Volume 134
Author(s): A. Jolt Oostra , Paul W.M. Blom , Jasper J. Michels
Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium hypochlorite to locally disrupt the conductivity of PEDOT:PSS by over-oxidation. We demonstrate that even macroscopically large defects with a surface area of 10mm2 can be repaired, restoring solar cell performance. In contrast, untreated defected solar cells exhibit a significantly increased leakage current and corresponding decrease in light-to-power conversion efficiency.
Source:Solar Energy Materials and Solar Cells, Volume 134
Author(s): A. Jolt Oostra , Paul W.M. Blom , Jasper J. Michels
Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium hypochlorite to locally disrupt the conductivity of PEDOT:PSS by over-oxidation. We demonstrate that even macroscopically large defects with a surface area of 10mm2 can be repaired, restoring solar cell performance. In contrast, untreated defected solar cells exhibit a significantly increased leakage current and corresponding decrease in light-to-power conversion efficiency.
Graphical abstract
26 Dec 12:08
Spontaneous phase separation of a zinc oxide interfacial layer in bulk heterojunction organic photovoltaics
Publication date: March 2015
Source:Solar Energy Materials and Solar Cells, Volume 134
Author(s): Yen-Sook Jung , Jun-Seok Yeo , Byung-Kwan Yu , Dong-Yu Kim
An interfacial layer and active layer were simultaneously fabricated through a facile one-step process using a blended solution of zinc oxide (ZnO) sol-gel as the interfacial material, and P3HT:PCBM (poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric methyl ester) as the photoactive components. The resultant devices based on the one-step process exhibited a favourable 3.56% power conversion efficiency (PCE) after a simple UV light treatment, close to the PCE of a conventionally fabricated reference device with a multilayer architecture. Using a combination of surface morphology analysis and investigation of the vertical component distribution, we confirmed that a spontaneous and significant phase separation between the ZnO and the photoactive materials occurred during the spin coating and sequential thermal annealing processes. This resulted in the automatic formation of an enriched ZnO interfacial layer at the ITO surface. The work function of the ZnO layer deposited by the one-step process on the ITO substrate was 3.76eV, consistent with conventionally formed ZnO layers. Furthermore, the performance of the device fabricated by the one-step process demonstrated superior stability under light exposure. This successful demonstration of organic photovoltaics (OPVs) using the one-step process is an important step towards the realization of high performance, roll-to-roll compatible OPVs.
Source:Solar Energy Materials and Solar Cells, Volume 134
Author(s): Yen-Sook Jung , Jun-Seok Yeo , Byung-Kwan Yu , Dong-Yu Kim
An interfacial layer and active layer were simultaneously fabricated through a facile one-step process using a blended solution of zinc oxide (ZnO) sol-gel as the interfacial material, and P3HT:PCBM (poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric methyl ester) as the photoactive components. The resultant devices based on the one-step process exhibited a favourable 3.56% power conversion efficiency (PCE) after a simple UV light treatment, close to the PCE of a conventionally fabricated reference device with a multilayer architecture. Using a combination of surface morphology analysis and investigation of the vertical component distribution, we confirmed that a spontaneous and significant phase separation between the ZnO and the photoactive materials occurred during the spin coating and sequential thermal annealing processes. This resulted in the automatic formation of an enriched ZnO interfacial layer at the ITO surface. The work function of the ZnO layer deposited by the one-step process on the ITO substrate was 3.76eV, consistent with conventionally formed ZnO layers. Furthermore, the performance of the device fabricated by the one-step process demonstrated superior stability under light exposure. This successful demonstration of organic photovoltaics (OPVs) using the one-step process is an important step towards the realization of high performance, roll-to-roll compatible OPVs.
Graphical abstract
20 Dec 10:30
8.7% Power conversion efficiency polymer solar cell realized with non-chlorinated solvents
Publication date: March 2015
Source:Solar Energy Materials and Solar Cells, Volume 134
Author(s): G. Susanna , L. Salamandra , C. Ciceroni , F. Mura , T.M. Brown , A. Reale , M. Rossi , A. Di Carlo , F. Brunetti
The use of environmental friendly solvents for the fabrication of solution processed organic photovoltaics is a key issue to scale up the technology. Nowadays however, toxic and harmful chlorinated solvents are largely used in polymer solar cell laboratory research. In this work we successfully reached high solubility and miscibility of the low band gap polymer Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PBDTTT-E-F, commonly known as PTB7), blended with [6,6]-Phenyl-C71-butyric acid methyl-ester ([70]PCBM fullerene derivative) in a non-chlorinated solvent (Dimethylbenzenes also known as Xylenes). We studied the solar cells realized depositing blend solutions based on various Xylenes (ortho, para and an isomeric mixture from technical grade) achieving high power conversion efficiencies up to 8.7%.
Source:Solar Energy Materials and Solar Cells, Volume 134
Author(s): G. Susanna , L. Salamandra , C. Ciceroni , F. Mura , T.M. Brown , A. Reale , M. Rossi , A. Di Carlo , F. Brunetti
The use of environmental friendly solvents for the fabrication of solution processed organic photovoltaics is a key issue to scale up the technology. Nowadays however, toxic and harmful chlorinated solvents are largely used in polymer solar cell laboratory research. In this work we successfully reached high solubility and miscibility of the low band gap polymer Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PBDTTT-E-F, commonly known as PTB7), blended with [6,6]-Phenyl-C71-butyric acid methyl-ester ([70]PCBM fullerene derivative) in a non-chlorinated solvent (Dimethylbenzenes also known as Xylenes). We studied the solar cells realized depositing blend solutions based on various Xylenes (ortho, para and an isomeric mixture from technical grade) achieving high power conversion efficiencies up to 8.7%.
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