29 Mar 14:31
Chem. Sci., 2019, 10,4282-4292
DOI: 10.1039/C8SC05514A, Edge Article
Open Access
Jiawang Zhou, Yilei Wu, Indranil Roy, Avik Samanta, J. Fraser Stoddart, Ryan M. Young, Michael R. Wasielewski
Photo-driven electron transfer is faster from an electron donor guest to the harder to reduce acceptor in an asymmetric cyclophane host.
The content of this RSS Feed (c) The Royal Society of Chemistry
27 Mar 12:37
by Steffen Roland, Juliane Kniepert, John A. Love, Vikas Negi, Feilong Liu, Peter Bobbert, Armantas Melianas, Martijn Kemerink, Andreas Hofacker, Dieter Neher
The Journal of Physical Chemistry Letters
DOI: 10.1021/acs.jpclett.9b00516
25 Mar 09:16
by Huawei Hu,
Long Ye,
Masoud Ghasemi,
Nrup Balar,
Jeromy James Rech,
Samuel J. Stuard,
Wei You,
Brendan T. O'Connor,
Harald Ade
A highly efficient, stable, and ductile nonfullerene ternary organic solar cell by integrating two polymer donors and one acceptor is achieved. The enhanced performance and stability are mainly attributed to the suppressed crystallization of the nonfullerene acceptor by introducing a stiff donor that shows low miscibility with the acceptor and a slightly higher highest occupied molecular orbital (HOMO) than the host polymer.
Abstract
Organic solar cells (OSCs) are one of the most promising cost‐effective options for utilizing solar energy, and, while the field of OSCs has progressed rapidly in device performance in the past few years, the stability of nonfullerene OSCs has received less attention. Developing devices with both high performance and long‐term stability remains challenging, particularly if the material choice is restricted by roll‐to‐roll and benign solvent processing requirements and desirable mechanical durability. Building upon the ink (toluene:FTAZ:IT‐M) that broke the 10% benchmark when blade‐coated in air, a second donor material (PBDB‐T) is introduced to stabilize and enhance performance with power conversion efficiency over 13% while keeping toluene as the solvent. More importantly, the ternary OSCs exhibit excellent thermal stability and storage stability while retaining high ductility. The excellent performance and stability are mainly attributed to the inhibition of the crystallization of nonfullerene small‐molecular acceptors (SMAs) by introducing a stiff donor that also shows low miscibility with the nonfullerene SMA and a slightly higher highest occupied molecular orbital (HOMO) than the host polymer. The study indicates that improved stability and performance can be achieved in a synergistic way without significant embrittlement, which will accelerate the future development and application of nonfullerene OSCs.
25 Mar 09:15
by Yuwei Xu,
Xiaoming Liang,
Xuehong Zhou,
Peisen Yuan,
Jiadong Zhou,
Cong Wang,
Binbin Li,
Dehua Hu,
Xianfeng Qiao,
Xiaofang Jiang,
Linlin Liu,
Shi‐Jian Su,
Dongge Ma,
Yuguang Ma
A pure‐blue fluorescent organic light‐emitting device (OLED) based on phenanthroimidazole−anthracene derivative obtains a maximum external quantum efficiency of 10.5% with excellent stability. Experimental investigations reveal that the high efficiency is attributed to triplet exciton harvesting by reverse intersystem crossing from the high‐lying triplet state. The results demonstrates that “hot exciton” channels represent a promising way to construct high‐performance fluorescent OLEDs.
Abstract
Purely organic electroluminescent materials, such as thermally activated delayed fluorescent (TADF) and triplet–triplet annihilation (TTA) materials, basically harness triplet excitons from the lowest triplet excited state (T1) to realize high efficiency. Here, a fluorescent material that can convert triplet excitons into singlet excitons from the high‐lying excited state (T2), referred to here as a “hot exciton” path, is reported. The energy levels of this compound are determined from the sensitization and nanosecond transient absorption spectroscopy measurements, i.e., small splitting energy between S1 and T2 and rather large T2–T1 energy gap, which are expected to impede the internal conversion (IC) from T2 to T1 and facilitate the reverse intersystem crossing from the high‐lying triplet state (hRISC). Through sensitizing the T2 state with ketones, the existence of the hRISC process with an ns‐scale delayed lifetime is confirmed. Benefiting from this fast triplet–singlet conversion, the nondoped device based on this “hot exciton” material reaches a maximum external quantum efficiency exceeding 10%, with a small efficiency roll‐off and CIE coordinates of (0.15, 0.13). These results reveal that the “hot exciton” path is a promising way to exploit high efficient, stable fluorescent emitters, especially for the pure‐blue and deep‐blue fluorescent organic light‐emitting devices.
25 Mar 09:15
by Yonghai Li,
Nan Zheng,
Lu Yu,
Shuguang Wen,
Chenglin Gao,
Mingliang Sun,
Renqiang Yang
An effective but simple approach to rationally tune the crystallinity and miscibility of small‐molecular acceptors is reported. With a phenyl introduced at the tail of alkyl side chains, the morphology and molecular orientations of heterojunction are greatly improved. Outstanding efficiencies of 13.23% and 14.04% are detected from the as‐cast and annealed devices, promoted by the fairly high fill factors.
Abstract
Research on fused‐ring small‐molecular‐acceptors (SMAs) has deeply advanced the development of organic solar cells (OSCs). Compared to fruitful studies of ladder‐type cores and end‐caps of SMAs, the exploration of side chains is monotonous. The widely utilized alkyl and aryl side chains usually produce a conflicting association between SMAs' crystallinity and miscibility. Herein, a fresh idea about the modification of side chains is reported to explore the subtle balance between the crystallinity and miscibility. Specifically, a phenyl is introduced to the tail of the alkyl side chain whereby a new acceptor IDIC‐C4Ph is reported. Moderately weakened crystallinity is observed, while maintaining preferred absorption profiles and face‐on orientations. Concurrently, remarkably improved heterojunction morphologies and stacking orientations are detected. PBDB‐T:IDIC‐C4Ph devices exhibit greater efficiency of 11.50% than devices from alky and aryl modified acceptors. Notably, the as‐cast OSCs of PBDB‐TF:IDIC‐C4Ph reveal outstanding FF over 76% with the best efficiency up to 13.23%. The annealed devices reveal further increased efficiency exceeding 14% with the state of the art FF of 78.32%. Overall, an effective but easily navigable approach is demonstrated to modulate the crystallinity of SMAs toward synergistically improved morphologies and molecular orientations of bulk heterojunction enabling highly efficient OSCs.
25 Mar 09:14
by Ke Gao,
Sae Byeok Jo,
Xueliang Shi,
Li Nian,
Ming Zhang,
Yuanyuan Kan,
Francis Lin,
Bin Kan,
Bo Xu,
Qikun Rong,
Lingling Shui,
Feng Liu,
Xiaobin Peng,
Guofu Zhou,
Yong Cao,
Alex K.‐Y. Jen
Nonfullerene‐based small‐molecule organic solar cells with a new record efficiency of 12.08% are achieved by first incorporation of near‐infrared absorbing molecules and by tuning the sequentially evolved crystalline morphology. The improved crystallinity of both donor and acceptor materials facilitates the formation of multilength scale morphologies, which further enhance charge mobility and extraction, and reduce the nongeminate recombination.
Abstract
In this paper, two near‐infrared absorbing molecules are successfully incorporated into nonfullerene‐based small‐molecule organic solar cells (NFSM‐OSCs) to achieve a very high power conversion efficiency (PCE) of 12.08%. This is achieved by tuning the sequentially evolved crystalline morphology through combined solvent additive and solvent vapor annealing, which mainly work on ZnP‐TBO and 6TIC, respectively. It not only helps improve the crystallinity of the ZnP‐TBO and 6TIC blend, but also forms multilength scale morphology to enhance charge mobility and charge extraction. Moreover, it simultaneously reduces the nongeminate recombination by effective charge delocalization. The resultant device performance shows remarkably enhanced fill factor and J
sc. These result in a very respectable PCE, which is the highest among all NFSM‐OSCs and all small‐molecule binary solar cells reported so far.
24 Mar 16:28
by Zhenghui Luo,
Tao Liu,
Yiling Wang,
Guangye Zhang,
Rui Sun,
Zhangxiang Chen,
Cheng Zhong,
Jingnan Wu,
Yuzhong Chen,
Maojie Zhang,
Yang Zou,
Wei Ma,
He Yan,
Jie Min,
Yongfang Li,
Chuluo Yang
The ITC‐2Cl‐based device yields an excellent power conversion efficiency of 13.6% with a low E
loss of 0.67 eV, which is superior to those of the devices based on ITCPTC, IT‐4F, and IT‐4Cl.
Abstract
Generally, highly efficient organic solar cells require both a high open‐circuit voltage (V
OC) and a high short‐circuit current density (J
SC). Reducing the energy loss (E
loss) is an effective way to achieve a high V
OC without compromising the photocurrent, which is ideal for enhancing the power conversion efficiencies (PCEs). Herein, a new chlorinated nonfullerene acceptor (ITC‐2Cl) with chlorinated thiophene‐fused end groups is developed. In comparison with the unchlorinated counterpart (ITCPTC), the introduction of Cl improves not only the electronic properties by redshifting the absorption spectra and deepening the lowest unoccupied molecular orbital energy levels, but also the molecular packing and thus thin‐film morphology. The PM6:ITC‐2Cl‐based device yields a significantly higher PCE (13.6%) with a lower E
loss (0.67 eV) than the ITCPTC‐based device (PCE of 12.3% with E
loss of 0.70 eV). More importantly, compared to the archetypal nonfullerene acceptors such as IT‐4F (PCE of 12.9% with E
loss of 0.73 eV) and IT‐4Cl (PCE of 12.7% with E
loss of 0.76 eV), the ITC‐2Cl‐based device shows a higher PCE and a lower E
loss. These results demonstrate that the chlorinated thiophene‐fused end group is a promising candidate for a high‐performance nonfullerene acceptors with low energy loss.
24 Mar 16:27
by Gongchu Liu,
Jianchao Jia,
Kai Zhang,
Xiao'e Jia,
Qingwu Yin,
Wenkai Zhong,
Li Li,
Fei Huang,
Yong Cao
A novel wide‐bandgap nonfullerene acceptor TfIF‐4FIC is synthesized. PBDB‐T‐2F:TfIF‐4FIC‐based organic solar cell acquires a power conversion efficiency (PCE) of 13.1%, a high open‐circuit voltage of 0.98 V, which is the best performed device with bandgap larger than 1.60 eV. When using PBDB‐T‐2F:TfIF‐4FIC as front cell and PTB7‐Th:PCDTBT:IEICO‐4F as back cell to construct tandem device, PCE of 15% is achieved.
Abstract
A tandem organic solar cell (OSC) is a valid structure to widen the photon response range and suppress the transmission loss and thermalization loss. In the past few years, the development of low‐bandgap materials with broad absorption in long‐wavelength region for back subcells has attracted considerable attention. However, wide‐bandgap materials for front cells that have both high short‐circuit current density (J
SC) and open‐circuit voltage (V
OC) are scarce. In this work, a new fluorine‐substituted wide‐bandgap small molecule nonfullerene acceptor TfIF‐4FIC is reported, which has an optical bandgap of 1.61 eV. When PBDB‐T‐2F is selected as the donor, the device offers an extremely high V
OC of 0.98 V, a high J
SC of 17.6 mA cm−2, and a power conversion efficiency of 13.1%. This is the best performing acceptor with such a wide bandgap. More importantly, the energy loss in this combination is 0.63 eV. These properties ensure that PBDB‐T‐2F:TfIF‐4FIC is an ideal candidate for the fabrication of tandem OSCs. When PBDB‐T‐2F:TfIF‐4FIC and PTB7‐Th:PCDTBT:IEICO‐4F are used as the front cell and the back cell to construct tandem solar cells, a PCE of 15% is obtained, which is one of best results reported to date in the field of organic solar cells.
24 Mar 16:26
by Jia Yang,
Cong Liu,
Chunsheng Cai,
Xiaotian Hu,
Zengqi Huang,
Xiaopeng Duan,
Xiangchuan Meng,
Zhongyi Yuan,
Licheng Tan,
Yiwang Chen
Fluorinated perylenediimide (F‐PDI) is first introduced to optimize photovoltaic performance and stability of perovskite solar cells. Conductive F‐PDI effectively passivates defects and promotes charge transfer. The hydrophobicity of F‐PDI preventing moisture penetration as well as the strong hydrogen bonding immobilizing methylamine ions, thereby, endow excellent moisture and thermal stability with nearly 70% efficiency retention after thermal treatment at 100 °C.
Abstract
The notoriously poor stability of perovskite solar cells is a crucial issue restricting commercial applications. Here, a fluorinated perylenediimide (F‐PDI) is first introduced into perovskite film to enhance the device's photovoltaic performance, as well as thermal and moisture stability simultaneously. The conductive F‐PDI molecules filling at grain boundaries (GBs) and surface of perovskite film can passivate defects and promote charge transport through GBs due to the chelation between carbonyl of F‐PDI and noncoordinating lead. Furthermore, an effective multiple hydrophobic structure is formed to protect perovskite film from moisture erosion. As a result, the F‐PDI‐incorporated devices based on MAPbI3 and Cs0.05 (FA0.83MA0.17)0.95 Pb (Br0.17I0.83)3 absorber achieve champion efficiencies of 18.28% and 19.26%, respectively. Over 80% of the initial efficiency is maintained after exposure in air for 30 days with a relative humidity (RH) of 50%. In addition, the strong hydrogen bonding of F···H‐N can immobilize methylamine ion (MA+) and thus enhances the thermal stability of device, remaining nearly 70% of the initial value after thermal treatment (100 °C) for 24 h at 50% RH condition.
24 Mar 14:23
by Jianyao Huang, Zhihui Chen, Jie Yang, Huanxin Ju, Weifeng Zhang, Gui Yu
Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b05353
24 Mar 14:22
by Xiaoliang Zou, Haonan Zhao, Yinwu Li, Qian Gao, Zhuofeng Ke, Senmiao Xu
Journal of the American Chemical Society
DOI: 10.1021/jacs.8b13756
19 Mar 09:22
by Long Ye, Wanbin Li, Xia Guo, Maojie Zhang, Harald Ade
Chemistry of Materials
DOI: 10.1021/acs.chemmater.9b00174
19 Mar 09:22
by Kun-Han Lin, Antonio Prlj, Liang Yao, Nikita Drigo, Han-Hee Cho, Mohammad Khaja Nazeeruddin, Kevin Sivula, Clémence Corminboeuf
Chemistry of Materials
DOI: 10.1021/acs.chemmater.9b00438
19 Mar 09:21
by Guobing Zhang, Yao Zhao, Boseok Kang, Sangsik Park, Jiufu Ruan, Hongbo Lu, Longzhen Qiu, Yunsheng Ding, Kilwon Cho
Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b05054
14 Mar 16:03
by Jin-Hu Dou, Zhi-Ao Yu, Jun Zhang, Yu-Qing Zheng, Ze-Fan Yao, Zeyi Tu, Xinchang Wang, Shiliang Huang, Chengwen Liu, Junliang Sun, Yuanping Yi, Xiaoyu Cao, Yiqin Gao, Jie-Yu Wang, Jian Pei
Journal of the American Chemical Society
DOI: 10.1021/jacs.8b13471
14 Mar 16:02
by Hyun-June Jang, Justine Wagner, Hui Li, Qingyang Zhang, Tushita Mukhopadhyaya, Howard E. Katz
Journal of the American Chemical Society
DOI: 10.1021/jacs.8b13026
12 Mar 02:17
by Jianqiu Wang,
Zhong Zheng,
Dongyang Zhang,
Jianqi Zhang,
Jiyu Zhou,
Jingchong Liu,
Shenkun Xie,
Yong Zhao,
Yuan Zhang,
Zhixiang Wei,
Jianhui Hou,
Zhiyong Tang,
Huiqiong Zhou
The molecular orientation and charge extraction of PEDOT:PSS‐based hole‐transporting layers are effectively modulated through fine tuning of the surface energy by introducing poly(styrene sulfonic acid) sodium salts or nickel formate dihydrate, which boosts the fill factor and eventual efficiency of organic solar cells based on fullerene and nonfullerene acceptors.
Abstract
Interface properties are of critical importance for high‐performance bulk‐heterojunction (BHJ) organic solar cells (OSCs). Here, a universal interface approach to tune the surface free energy (γS) of hole‐transporting layers (HTLs) in a wide range through introducing poly(styrene sulfonic acid) sodium salts or nickel formate dihydrate into poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is reported. Based on the optimal γS of HTLs and thus improved face‐on molecular ordering in BHJs, enhanced fill factor and power conversion efficiencies in both fullerene and nonfullerene OSCs are achieved, which is attributed to the increased charge carrier mobility and sweepout with reduced recombination. It is found that the face‐on orientation‐preferred BHJs (PBDB‐TF:PC71BM, PBDB‐T:PC71BM, and PBDB‐TF:IT‐4F) favor HTLs with higher γS while the edge‐on orientation‐preferred BHJs (PDCDT:PC71BM, P3HT:PC71BM and PDCBT:ITIC) are partial to HTLs with lower γS. Based on the surface property–morphology–device performance correlations, a suggestion to select a suitable HTL in terms of γS for a specific BHJ with favored molecular arrangement is provided. This work enriches the fundamental understandings on the interface characteristics and morphological control toward high‐efficiency OSCs based on a wide range of BHJ materials.
10 Mar 15:13
by Yuichiro Watanabe,
Daisuke Yokoyama,
Tomoyuki Koganezawa,
Hiroshi Katagiri,
Takashi Ito,
Satoru Ohisa,
Takayuki Chiba,
Hisahiro Sasabe,
Junji Kido
Self‐complementary weak hydrogen bonds of oligopyridines can be used to control molecular orientation for designing horizontally oriented yet amorphous organic semiconductor films. Synergetic effects of disordered hydrogen bonds and planar anisotropic molecular shapes enhance horizontal molecular orientation and significantly increasing electron mobility. This molecular engineering methodology delivers a highly efficient and stable organic optoelectronic device as a proof‐of‐concept.
Abstract
Use of the intrinsic optoelectronic functions of organic semiconductor films has not yet reached its full potential, mainly because of the primitive methodology used to control the molecular aggregation state in amorphous films during vapor deposition. Here, a universal molecular engineering methodology is presented to control molecular orientation; this methodology strategically uses noncovalent, intermolecular weak hydrogen bonds in a series of oligopyridine derivatives. A key is to use two bipyridin‐3‐ylphenyl moieties, which form self‐complementary intermolecular weak hydrogen bonds, and which do not induce unfavorable crystallization. Another key is to incorporate a planar anisotropic molecular shape by reducing the steric hindrance of the core structure for inducing π–π interactions. These synergetic effects enhance horizontal orientation in amorphous organic semiconductor films and significantly increasing electron mobility. Through this evaluation process, an oligopyridine derivative is selected as an electron‐transporter, and successfully develops highly efficient and stable deep‐red organic light‐emitting devices as a proof‐of‐concept.
10 Mar 15:09
by S. D. Dimitrov, M. Azzouzi, J. Wu, J. Yao, Y. Dong, P. Shakya Tuladhar, B. C. Schroeder, E. R. Bittner, I. McCulloch, J. Nelson, J. R. Durrant
Journal of the American Chemical Society
DOI: 10.1021/jacs.8b11484
06 Mar 06:01
by Yuanhong Gao,
Ya Yi,
Xinwei Wang,
Hong Meng,
Dangyuan Lei,
Xue‐Feng Yu,
Paul K. Chu,
Jia Li
A novel hybrid‐layered organic phototransistor, (HL‐OPT) architecture consisting of an organic semiconductor channel layer for fast carrier transport, a photoactive organic bulk‐heterojunction layer, and an ultrathin inorganic interlayer sandwiched in between is proposed. By combining the virtues of the charge‐trapping effect and efficient carrier transport simultaneously, significant enhancement in the photodetection performance is achieved from the fabricated HL‐OPT.
Abstract
The interfacial charge effect is crucial for high‐sensitivity organic phototransistors (OPTs), but conventional layered and hybrid OPTs have a trade‐off in balancing the separation, transport, and recombination of photogenerated charges, consequently impacting the device performance. Herein, a novel hybrid‐layered phototransistor (HL‐OPT) is reported with significantly improved photodetection performance, which takes advantages of both the charge‐trapping effect (CTE) and efficient carrier transport. The HL‐OPT consisting of 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) as conduction channel, C8‐BTBT:[6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) bulk heterojunction as photoactive layer, and sandwiched MoO3 interlayer as a charge‐transport interlayer exhibits outstanding photodetection characteristics such as a photosensitivity (I
light/I
dark) of 2.9 × 106, photoresponsivity (R) of 8.6 × 103 A W−1, detectivity (D*) of 3.4 × 1014 Jones, and external quantum efficiency of 3 × 106% under weak light illumination of 32 µW cm−2. The mechanism and strategy described here provide new insights into the design and optimization of high‐performance OPTs spanning the ultraviolet and near infrared (NIR) range as well as fundamental issues pertaining to the electronic and photonic properties of the devices.
06 Mar 06:00
by Fanji Wang, Kyohei Nakano, Hiroshi Segawa, Keisuke Tajima
Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b05240
02 Mar 18:00
by Joel Luke,
Emily M. Speller,
Andrew Wadsworth,
Mark F. Wyatt,
Stoichko Dimitrov,
Harrison K. H. Lee,
Zhe Li,
Wing C. Tsoi,
Iain McCulloch,
Diego Bagnis,
James R. Durrant,
Ji‐Seon Kim
Nonfullerene acceptors (NFAs) provide an exciting prospect for organic solar cells; however, their stability still lacks fundamental understanding. The promising high‐efficiency NFAs, IDTBR and IDFBR, show a three‐phase degradation mechanism, which involves a strong initial molecular conformational change prior to photodegradation under light and oxygen stress, indicating the important role of NFA molecular structure in solar cell stability.
Abstract
Nonfullerene acceptors (NFAs) dominate organic photovoltaic (OPV) research due to their promising efficiencies and stabilities. However, there is very little investigation into the molecular processes of degradation, which is critical to guiding design of novel NFAs for long‐lived, commercially viable OPVs. Here, the important role of molecular structure and conformation in NFA photostability in air is investigated by comparing structurally similar but conformationally different promising NFAs: planar O‐IDTBR and nonplanar O‐IDFBR. A three‐phase degradation process is identified: i) initial photoinduced conformational change (i.e., torsion about the core–benzothiadiazole dihedral), induced by noncovalent interactions with environmental molecules, ii) followed by photo‐oxidation and fragmentation, leading to chromophore bleaching and degradation product formation, and iii) finally complete chromophore bleaching. Initial conformational change is a critical prerequisite for further degradation, providing fundamental understanding of the relative stability of IDTBR and IDFBR, where the already twisted IDFBR is more prone to degradation. When blended with the donor polymer poly(3‐hexylthiophene), both NFAs exhibit improved photostability while the photostability of the polymer itself is significantly reduced by the more miscible twisted NFA. The findings elucidate the important role of NFA molecular structure in photostability of OPV systems, and provide vital insights into molecular design rules for intrinsically photostable NFAs.
02 Mar 18:00
by Lili Lu,
Qing Liao,
Yunfei Zu,
Ye Xu,
Bowei Xu,
Jianhui Hou
Through the rational molecular design of fluorination, the work function of the conjugated polymer (CP) is enhanced from 4.83 to 5.00 eV. Consequently, the CP can be used to modify efficient active layers consisting of polymer donors with a deep HOMO level, such as PBDB‐T‐2F:IT‐4F, and an outstanding power conversion efficiency of 12.7% is achieved in the corresponding device without V
oc loss.
Abstract
Since the highest occupied molecular orbital (HOMO) level of donors in organic solar cells (OSCs) is being constantly downshifted for achieving high open‐circuit voltage (V
oc), a further enhancement of the anode work function (WF) is required. Herein, an effective approach of fluorination is demonstrated to simultaneously improve the WF and transparency for anode interlayer (AIL) material. By fluorination, in combination with the dialysis treatment in LiCl solution, the WF of PCP‐2F‐Li could be significantly enhanced from 4.86 to 5.0 eV, as compared to PCP‐Na. Meanwhile, the transparency of the polymer is also improved. As a result, PCP‐2F‐Li can be used to modify efficient active layers consisting of polymer donors with deep HOMO levels, such as PBDB‐T‐2F:IT‐4F, and an outstanding power conversion efficiency (PCE) of 12.7% is achieved in the corresponding device with a high V
oc of 0.84 V. This result represents the highest efficiency for the OSCs using a solution‐processed pH‐neutral AIL, which is beneficial to the low‐cost fabrication of high‐performance OSCs with improved stability. More importantly, PCP‐2F‐Li could be processed by blade coating for making large‐area device of 1 cm2, and a PCE of 10.6% is achieved, bringing a promising prospect for the large‐area device fabrication.
27 Feb 06:22
by Huifang Li, Minki Hong, Annabelle Scarpaci, Xuyang He, Chad Risko, John S. Sears, Stephen Barlow, Paul Winget, Seth R. Marder, Dongwook Kim, Jean-Luc Brédas
Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b04235
27 Feb 03:35
by Yong Cui,
Huifeng Yao,
Ling Hong,
Tao Zhang,
Ye Xu,
Kaihu Xian,
Bowei Gao,
Jinzhao Qin,
Jianqi Zhang,
Zhixiang Wei,
Jianhui Hou
Organic solar cells achieve over 15% efficiency through the use of a copolymer donor, and simultaneously enhanced open‐circuit voltage and short‐circuit current density are obtained. High‐performance solar cells are adaptable for environment‐friendly solvents using a blade‐coating method, while showing better photostability than the corresponding ternary solar cells.
Abstract
Ternary blending and copolymerization strategies have proven advantageous in boosting the photovoltaic performance of organic solar cells. Here, 15% efficiency solar cells using copolymerization donors are demonstrated, where the electron‐withdrawing unit, ester‐substituted thiophene, is incorporated into a PBDB‐TF polymer to downshift the molecular energy and broaden the absorption. Copolymer‐based solar cells suitable for large‐area devices can be fabricated by a blade‐coating method from a nonhalogen and nonaromatic solvent mixture. Although ternary solar cells can achieve comparable efficiencies, they are not suitable for environment‐friendly processing conditions and show relatively low photostability compared to copolymer‐based devices. These results not only demonstrate high‐efficiency organic photovoltaic cells via copolymerization strategies but also provide important insights into their applications in practical production.
27 Feb 03:34
by Jia Sun,
Yongsuk Choi,
Young Jin Choi,
Seongchan Kim,
Jin‐Hong Park,
Sungjoo Lee,
Jeong Ho Cho
The hybridization of 2D materials and organic materials represents a promising domain for the realization of improved or unprecedented features in comparison to those of semiconductor devices. This comprehensive review focuses on emerging 2D–organic heterostructures (from their synthesis and fabrication to their state‐of‐the‐art optoelectronic applications) and highlights the future challenges and opportunities associated with these heterostructures.
Abstract
The unique properties of hybrid heterostructures have motivated the integration of two or more different types of nanomaterials into a single optoelectronic device structure. Despite the promising features of organic semiconductors, such as their acceptable optoelectronic properties, availability of low‐cost processes for their fabrication, and flexibility, further optimization of both material properties and device performances remains to be achieved. With the emergence of atomically thin 2D materials, they have been integrated with conventional organic semiconductors to form multidimensional heterostructures that overcome the present limitations and provide further opportunities in the field of optoelectronics. Herein, a comprehensive review of emerging 2D–organic heterostructures—from their synthesis and fabrication to their state‐of‐the‐art optoelectronic applications—is presented. Future challenges and opportunities associated with these heterostructures are highlighted.
27 Feb 03:33
by Lothar Weinhardt,
Dirk Hauschild,
Clemens Heske
Electron and soft X‐ray spectroscopies are powerful techniques to study the chemical and electronic structure of surfaces and interfaces. In this progress report, these techniques are used to study solar devices and to unravel some of the most pertinent aspects of recent cutting‐edge developments (and world‐record efficiency improvements) in chalcopyrite thin‐film solar cells.
Abstract
Thin‐film solar cells have great potential to overtake the currently dominant silicon‐based solar cell technologies in a strongly growing market. Such thin‐film devices consist of a multilayer structure, for which charge‐carrier transport across interfaces plays a crucial role in minimizing the associated recombination losses and achieving high solar conversion efficiencies. Further development can strongly profit from a high‐level characterization that gives a local, electronic, and chemical picture of the interface properties, which allows for an insight‐driven optimization. Herein, the authors' recent progress of applying a “toolbox” of high‐level laboratory‐ and synchrotron‐based electron and soft X‐ray spectroscopies to characterize the chemical and electronic properties of such applied interfaces is provided. With this toolbox in hand, the activities are paired with those of experts in thin‐film solar cell preparation at the cutting edge of current developments to obtain a deeper understanding of the recent improvements in the field, e.g., by studying the influence of so‐called “post‐deposition treatments”, as well as characterizing the properties of interfaces with alternative buffer layer materials that give superior efficiencies on large, module‐sized areas.
27 Feb 03:31
by Zewdneh Genene,
Wendimagegn Mammo,
Ergang Wang,
Mats R. Andersson
The rapid development of n‐type polymers has boosted the efficiency of all‐polymer solar cells, which has improved from 2% to 10 % in only seven years. There is a strong need to summarize the design criteria, synthesis, structure–property relationships and recent advances of n‐type polymers, which is addressed in this review. Moreover, the challenges and prospects for further development of all‐PSCs are briefly discussed.
Abstract
All‐polymer solar cells (all‐PSCs) based on n‐ and p‐type polymers have emerged as promising alternatives to fullerene‐based solar cells due to their unique advantages such as good chemical and electronic adjustability, and better thermal and photochemical stabilities. Rapid advances have been made in the development of n‐type polymers consisting of various electron acceptor units for all‐PSCs. So far, more than 200 n‐type polymer acceptors have been reported. In the last seven years, the power conversion efficiency (PCE) of all‐PSCs rapidly increased and has now surpassed 10%, meaning they are approaching the performance of state‐of‐the‐art solar cells using fullerene derivatives as acceptors. This review discusses the design criteria, synthesis, and structure–property relationships of n‐type polymers that have been used in all‐PSCs. Additionally, it highlights the recent progress toward photovoltaic performance enhancement of binary, ternary, and tandem all‐PSCs. Finally, the challenges and prospects for further development of all‐PSCs are briefly considered.
25 Feb 13:09
by Minghui Hao, Tao Liu, Yiqun Xiao, Lik-Kuen Ma, Guangye Zhang, Cheng Zhong, Zhanxiang Chen, Zhenghui Luo, Xinhui Lu, He Yan, Lei Wang, Chuluo Yang
Chemistry of Materials
DOI: 10.1021/acs.chemmater.8b05327
25 Feb 13:08
by Dylan T. Christiansen, Aimée L. Tomlinson, John R. Reynolds
Journal of the American Chemical Society
DOI: 10.1021/jacs.9b01507
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