J. Mater. Chem. A, 2019, 7,19008-19016 DOI: 10.1039/C9TA03336J, Paper
Yuxiao Guo, Xingtian Yin, Jie Liu, Wenxiu Que An efficient and facile one-step spin-coating method assisted by a preheating process was applied for the fabrication of high-quality CsPbIBr2 films. The content of this RSS Feed (c) The Royal Society of Chemistry
Nanoscale, 2019, 11,14676-14683 DOI: 10.1039/C9NR04787E, Paper
Zhixing Gan, Fei Zheng, Wenxin Mao, Chunhua Zhou, Weijian Chen, Udo Bach, Patrick Tapping, Tak W. Kee, Jeffrey A. Davis, Baohua Jia, Xiaoming Wen The green fluorescence of CsPbBr3–Cs4PbBr6 perovskite composites is ascribed to the emissions of band-edge and the defect trapped exciton of CsPbBr3. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,18488-18498 DOI: 10.1039/C9TA05948B, Paper
Bhaskar Parida, Jun Ryu, Saemon Yoon, Seojun Lee, Yejin Seo, Jung Sang Cho, Dong-Won Kang The dynamic CsBr treatment on α-CsPbI3 significantly improves the power conversion efficiency, reproducibility, and stability of all-inorganic CsPbI3−xBrx perovskite solar cells. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. C, 2019, 7,9455-9459 DOI: 10.1039/C9TC03111A, Communication
Zihao Dong, Xinxing Yin, Amjad Ali, Jie Zhou, Sandip Singh Bista, Cong Chen, Yanfa Yan, Weihua Tang A dithieno[3,2-b:2′,3′-d]pyrrole-cored four-arm hole transporting material has been designed to realize over 19% efficiency dopant-free perovskite solar cells. The content of this RSS Feed (c) The Royal Society of Chemistry
Nanoscale, 2019, 11,14465-14471 DOI: 10.1039/C9NR04801D, Paper
Fuchang Wang, Weiping Li, Huicong Liu, Liqun Zhu, Haining Chen A cation substitution strategy has been developed to fabricate highly pure perovskite precursor and high-quality perovskite films. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,18626-18633 DOI: 10.1039/C9TA06317J, Paper
Lisha Xie, Jianwei Wang, Kejun Liao, Jin-an Yang, Aili Wang, Xiaoyu Deng, Chengbo Li, Tingshuai Li, Xiaobin Niu, Feng Hao Low cost coenzyme Q10 as an alternative electron transport layer with improved carrier injection ability, passivated interface defects and better stability. The content of this RSS Feed (c) The Royal Society of Chemistry
by Joachim Vollbrecht,
Viktor V. Brus,
Seo‐Jin Ko,
Jaewon Lee,
Akchheta Karki,
David Xi Cao,
Kilwon Cho,
Guillermo C. Bazan,
Thuc‐Quyen Nguyen
A comprehensive analytical model capable of quantifying bimolecular, bulk and surface trap‐assisted contributions to the overall nongeminate recombination losses in organic solar cells is reported. Common techniques such as light intensity‐dependent current density–voltage characteristics, capacitance spectroscopy, and open‐circuit voltage decay yield the necessary experimental data to successfully apply this analytical model.
Abstract
In this study, a comprehensive analytical model to quantify the total nongeminate recombination losses, originating from bimolecular as well as bulk and surface trap‐assisted recombination mechanisms in nonfullerene‐based bulk heterojunction organic solar cells is developed. This proposed model is successfully employed to obtain the different contributions to the recombination current of the investigated solar cells under different illumination intensities. Additionally, the model quantitatively describes the experimentally measured open‐circuit voltage versus light intensity dependence. Most importantly, it is possible to calculate the experimental results with the same fitting parameter values from the presented model. The validity of this model is also proven by a combination of other independent, steady‐state, and transient experimental techniques. This new powerful analytical tool will enable researchers in the photovoltaic community to take into account the synergetic contribution from all relevant types of nongeminate recombination losses in different optoelectronic systems and target their analysis of recombination dynamics at any operating voltage.
by Boer Tan,
Sonia R. Raga,
Anthony S. R. Chesman,
Sebastian O. Fürer,
Fei Zheng,
David P. McMeekin,
Liangcong Jiang,
Wenxin Mao,
Xiongfeng Lin,
Xiaoming Wen,
Jianfeng Lu,
Yi‐Bing Cheng,
Udo Bach
Spiro‐OMeTAD(TFSI)2 is successfully employed in the fabrication of highly efficient n–i–p perovskite solar cells as a p‐dopant in the absence of lithium bis(trifluoromethane)sulfonimide (LiTFSI) and air exposure. With this approach, the proportion of [spiro‐OMeTAD]+ is precisely controlled, and the spiro‐OMeTAD(TFSI)2‐doped devices show a remarkably improved long‐term stability and well‐retained hole‐transporting material (HTM) morphology after aging for 300 h.
Abstract
To date, the most efficient perovskite solar cells (PSCs) employ an n–i–p device architecture that uses a 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) hole‐transporting material (HTM), which achieves optimum conductivity with the addition of lithium bis(trifluoromethane)sulfonimide (LiTFSI) and air exposure. However, this additive along with its oxidation process leads to poor reproducibility and is detrimental to stability. Herein, a dicationic salt spiro‐OMeTAD(TFSI)2, is employed as an effective p‐dopant to achieve power conversion efficiencies of 19.3% and 18.3% (apertures of 0.16 and 1.00 cm2) with excellent reproducibility in the absence of LiTFSI and air exposure. As far as it is known, these are the highest‐performing n–i–p PSCs without LiTFSI or air exposure. Comprehensive analysis demonstrates that precise control of the proportion of [spiro‐OMeTAD]+ directly provides high conductivity in HTM films with low series resistance, fast hole extraction, and lower interfacial charge recombination. Moreover, the spiro‐OMeTAD(TFSI)2‐doped devices show improved stability, benefitting from well‐retained HTM morphology without forming aggregates or voids when tested under an ambient atmosphere. A facile approach is presented to fabricate highly efficient PSCs by replacing LiTFSI with spiro‐OMeTAD(TFSI)2. Furthermore, this study provides an insight into the relationship between device performance and the HTM doping level.
by Ki‐Won Seo,
Jaemin Lee,
Jihwan Jo,
Changsoon Cho,
Jung‐Yong Lee
A poly(3,4‐ethylenedioxythiophene)‐free and indium tin oxide (ITO)‐free junction‐free AgNN electrode with high optoelectrical properties is proposed for flexible organic solar cells (FOSCs). The electrical sheet resistance and optical transmittance can be controlled by both initial metal thickness and NN density; even a very thin Ag layer with appropriate NN density can show high transmittance and low sheet resistance, yielding a highly efficient FOSC.
Abstract
A novel approach to fabricate flexible organic solar cells is proposed without indium tin oxide (ITO) and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) using junction‐free metal nanonetworks (NNs) as transparent electrodes. The metal NNs are monolithically etched using nanoscale shadow masks, and they exhibit excellent optoelectronic performance. Furthermore, the optoelectrical properties of the NNs can be controlled by both the initial metal layer thickness and NN density. Hence, with an extremely thin silver layer, the appropriate density control of the networks can lead to high transmittance and low sheet resistance. Such NNs can be utilized for thin‐film devices without planarization by conductive materials such as PEDOT:PSS. A highly efficient flexible organic solar cell with a power conversion efficiency (PCE) of 10.6% and high device yield (93.8%) is fabricated on PEDOT‐free and ITO‐free transparent electrodes. Furthermore, the flexible solar cell retains 94.3% of the initial PCE even after 3000 bending stress tests (strain: 3.13%).
by Kai Wang,
Waqas Siddique Subhani,
Yulong Wang,
Xiaokun Zuo,
Hui Wang,
Lianjie Duan,
Shengzhong (Frank) Liu
The progress of research into metal cations for perovskite solar cells is discussed by focusing on the locations of the cations in perovskites, the modulation of the film quality, and the influence on the photovoltaic performance. Metal cations are considered in the order of alkali cations, alkaline earth cations, and then metal cations in the ds and d regions, and ultimately trivalent cations.
Abstract
Metal halide perovskite solar cells (PVSCs) have revolutionized photovoltaics since the first prototype in 2009, and up to now the highest efficiency has soared to 24.2%, which is on par with commercial thin film cells and not far from monocrystalline silicon solar cells. Optimizing device performance and improving stability have always been the research highlight of PVSCs. Metal cations are introduced into perovskites to further optimize the quality, and this strategy is showing a vigorous development trend. Here, the progress of research into metal cations for PVSCs is discussed by focusing on the position of the cations in perovskites, the modulation of the film quality, and the influence on the photovoltaic performance. Metal cations are considered in the order of alkali cations, alkaline earth cations, then metal cations in the ds and d regions, and ultimately trivalent cations (p‐ and f‐block metal cations) according to the periodic table of elements. Finally, this work is summarized and some relevant issues are discussed.
There is a requirement to develop more effective hole-transporting materials (HTMs) than commonly used 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) to fabricate highly efficient and stable perovskite solar cells. Herein, we reported a new HTM of N [2],N2,N [5],N5,N [11],N11-hexakis(4-methoxyphenyl)indolo[3,2,1-jk]carbazole-2,5,11-triamine (DCZ-OMeTAD) by employing indolo[3,2,1-jk]carbazole (DCZ) as a central building block. In addition, another DCZ-based HTM named as 4,4′,4''-(indolo[3,2,1-jk]carbazole-2,5,11-triyl)tris(N,N-bis(4-methoxyphenyl)aniline) (DCZ-OMeTPA) with different arylamines as the electron-rich branch was also synthesized for comparison. CH3NH3PbI3 and (NH2CHNH2PbI3)1-x(CH3NH3PbI3)x based perovskite solar cells (PSCs) by utilizing the low-cost DCZ-OMeTAD as HTM exhibited the power conversion efficiency (PCE) of 19.81% and 21.66%, respectively, which were significantly higher than those of Spiro-OMeTAD based devices (18.06% and 20.08%). Unfortunately, DCZ-OMeTPA based PSCs presented unsatisfied device performance compared with Spiro-OMeTAD based devices. We ascribe it to the inferior charge-extraction capability and poor hole mobility of DCZ-OMeTPA. What's more, DCZ-OMeTAD based device also delivered the best cell stability among three HTMs based PSCs, indicating that the newly designed concept by replacing spirobifluorene with DCZ has good potential for developing effective HTMs for high-performance PSCs.
A series of organic solar cells (OSCs) were prepared with J71 as donor and IT-4F, T6Me or T6Me:IT-4F as acceptor(s), respectively. The two binary OSCs exhibit the same open circuit voltage (VOC), complementary short circuit current density (JSC) and fill factor (FF). The same VOC of binary OSCs with J71 as donor indicate the similar lowest unoccupied molecular orbits (LUMO) levels of IT-4F and T6Me. Meanwhile, IT-4F and T6Me have complementary photon harvesting range, exhibiting great potential in preparing efficient ternary OSCs. The optimized ternary OSCs exhibit a 13.16% power conversion efficiency (PCE) with 50 wt% IT-4F in acceptors, resulting from the enhanced JSC and FF. The FFs of ternary OSCs can be gradually improved along with IT-4F content increase, indicating that the two acceptors may prefer to form an alloyed state. The alloyed state of two acceptors should be beneficial to Förster energy transfer from IT-4F to T6Me, providing another channel for improving exciton utilization efficiency. This work indicates that alloyed model should have great potential in preparing efficient ternary OSCs with large content of the third component by fully exerting the advantages of used materials.
Graphical abstract
Ternary organic solar cells with 13.16% efficiency by recombining the advantages of used materials and the corresponding binary OSCs.
Energy Environ. Sci., 2019, 12,2860-2889 DOI: 10.1039/C9EE01591D, Review Article
Deepak Thrithamarassery Gangadharan, Dongling Ma Two-dimensional perovskites are an attractive alternative to 3D perovskites for solar cell application as they directly address a critical issue of stability of 3D perovskite solar cells, while achieving similarly high power conversion efficiencies. The content of this RSS Feed (c) The Royal Society of Chemistry
by Xinxing Yin,
Jie Zhou,
Zhaoning Song,
Zihao Dong,
Qinye Bao,
Niraj Shrestha,
Sandip Singh Bista,
Randy J. Ellingson,
Yanfa Yan,
Weihua Tang
A new dopant‐free hole transport material DTP‐C6Th is developed for efficient planar n‐i‐p perovskite solar cells. The champion power conversion efficiency (PCE) reaches 21.04% after careful device engineering with poly(methyl methacrylate) passivation and composition tuning of perovskite. The DTP‐C6Th‐based devices without encapsulation show no PCE drop in the glovebox and retain over 85% of the initial PCE in air after storage for 60 days.
Abstract
Dopant‐free hole transport materials (HTMs) are essential for commercialization of perovskite solar cells (PSCs). However, power conversion efficiencies (PCEs) of the state‐of‐the‐art PSCs with small molecule dopant‐free HTMs are below 20%. Herein, a simple dithieno[3,2‐b:2′,3′‐d]pyrrol‐cored small molecule, DTP‐C6Th, is reported as a promising dopant‐free HTM. Compared with commonly used spiro‐OMeTAD, DTP‐C6Th exhibits a similar energy level, a better hole mobility of 4.18 × 10−4 cm2 V−1 s−1, and more efficient hole extraction, enabling efficient and stable PSCs with a dopant‐free HTM. With the addition of an ultrathin poly(methyl methacrylate) passivation layer and properly tuning the composition of the perovskite absorber layer, a champion PCE of 21.04% is achieved, which is the highest value for small molecule dopant‐free HTM based PSCs to date. Additionally, PSCs using the DTP‐C6Th HTM exhibit significantly improved long‐term stability compared with the conventional cells with the metal additive doped spiro‐OMeTAD HTM. Therefore, this work provides a new candidate and effective device engineering strategy for achieving high PCEs with dopant‐free HTMs.
by Kai Wang*†?, Xiaoyang Liu‡?, Rong Huang‡, Congcong Wu†, Dong Yang†, Xiaowen Hu§, Xiaofang Jiang§, James C. Duchamp‡, Harry Dorn*‡, and Shashank Priya*†
by Antonio Agresti†‡¶, Sara Pescetelli†¶, Alessandro Lorenzo Palma†, Beatriz Marti´n-Garci´a§?, Leyla Najafi§, Sebastiano Bellani§, Iwan Moreels?, Mirko Prato?, Francesco Bonaccorso*§#, and Aldo Di Carlo*†‡
Author(s): Min Wang, Fengren Cao, Kaimo Deng, Liang Li
Abstract
Organic-inorganic perovskite solar cells have attracted extensive attentions due to the advantages such as high power conversion efficiency and easy fabrication over other counterparts. Mixed-cation perovskite is considered as one of the most efficient light absorbers for perovskite solar cells and the device performance has a close connection to the quality of the perovskite thin film. Herein, we systematically investigate the influence of adduct phase in the mixed-cation perovskite precursor film on the crystallization of the perovskite. By tuning the adduct phase through solvent engineering, we successfully optimize the morphology and optoelectronic properties of the perovskite film and the planar-type perovskite solar cells with a power conversion efficiency over 21% can be achieved. Our work provides an effective method to control the growth of the mixed-cation perovskite film and thus boost the device performance with enhanced efficiency and stability.
Graphical abstract
The manipulation of intermediate adduct phase in mixed-cation perovskite precursor through solvent engineering is demonstrated, which leads to the formation of high-quality perovskite films with an increased grain size and improved optoelectronic properties. An impressive power conversion efficiency of 21.2% is achieved for planar-type perovskite solar cells.
Electronic traps are the primary factor stifling the performance of quantum-dot (QD) solar cells to nearly half their theoretical potential. Yet, the exact origin of these traps remains largely unknown, making it difficult to address the problem. In the inaugural issue of Matter, Gilmore et al. employ advanced transient spectroscopy to reveal that QD dimerization can be as detrimental as unpassivated surface states in QD films.
J. Mater. Chem. A, 2019, 7,18898-18905 DOI: 10.1039/C9TA05048E, Paper
Wenxiao Zhang, Li Wan, Xiaodong Li, Yulei Wu, Sheng Fu, Junfeng Fang High efficiency and stable planar perovskite solar cells based on a dopant-free polyelectrolyte P3CT-BN hole transport layer. The content of this RSS Feed (c) The Royal Society of Chemistry
Diboron‐treated SnO2 exhibits some Sn3+ species, which serve as electron donors with more n‐type nature, resulting in the higher Fermi level on the surface of SnO2, promoting electron extraction and reducing carrier recombination in the electron transport layer (ETL)/perovskite interface. A power‐conversion efficiency of 22.04% is obtained in an n‐i‐p structure perovskite solar cell.
Energy‐level modulation between perovskite and carrier transport layers to obtain a promoted carrier extraction and reduced charge recombination is an effective way to achieve high‐efficiency perovskite solar cells. Here, diboron is used as an effective interfacial modifier between SnO2 and perovskite. By taking advantage of the higher Fermi level on the surface of SnO2 after diboron treatment, a power‐conversion efficiency of 22.04% in a solar cell device based on two‐step solution‐processed planar n‐i‐p structure is obtained. With the help of thorough characterizations, it is argued that the diboron‐treated SnO2 exhibits some Sn3+ species, which serve as electron donors with a more n‐type nature, promoting electron extraction and reducing carrier recombination in the electron transport layer (ETL)/perovskite interface. Further analysis speculates that the formation of surface diboron–oxygen Lewis pair induces a reducing state of diboron complexes, resulting in the spontaneous electron redistribution and the formation of Sn3+−O–• species. This provides an effective chemical approach to tune the energy alignment between the oxide ETL and absorber.
by Qiang Sun,
Hao Li,
Xiu Gong,
Huaxia Ban,
Yan Shen,
Mingkui Wang
An interconnected SnO2 thin film (composed of presynthesized SnO2 nanocrystals interconnected by amorphous phase SnOx) is proposed as an electron transport layer for efficient flexible perovskite solar cells. The interconnected SnO2 thin film enables fast electron extraction from the perovskite layer and retards nonradiative charge carrier recombination. Corresponding flexible solar cells demonstrate a power conversion efficiency as high as 16.29%.
This study reports on interconnected SnO2 electron transport layers (composed of presynthesized SnO2 nanocrystals interconnected by amorphous phase SnOx) processed at low temperature (120 °C) for highly efficient flexible perovskite solar cells. Herein, the amorphous phase SnOx serves as an effective binder to connect the SnO2 nanocrystals to obtain ultra‐smooth electron transport layers. Further characterization of the charge carrier kinetics at the perovskite/electron transport layer interface confirms that the interconnected SnO2 nanocrystals layer facilitates electron extraction and retards nonradiative charge carrier recombination. Consequently, a power conversion efficiency of 16.29% is achieved for flexible perovskite solar cells using the interconnected SnO2 electron transport layer on indium tin oxide/polyethylene terephthalate substrates.
by Wang, K., Wu, C., Jiang, Y., Yang, D., Wang, K., Priya, S.
Two-dimensional (2D) lead halide perovskite with a natural "multiple quantum well" (MQW) structure has shown great potential for optoelectronic applications. Continuing advancement requires a fundamental understanding of the charge and energy flow in these 2D heterolayers, particularly at the layer edges. Here, we report the distinct conducting feature at the layer edges between the insulating bulk terrace regions in the (C4H9NH3)2PbI4 2D perovskite single crystal. The edges of the 2D exhibit an extraordinarily large carrier density of ~1021 cm–3. By using various mapping techniques, we found the layer edge electrons are not related to the surface charging effect; rather, they are associated with the local nontrivial energy states of the electronic structure at the edges. This observation of the metal-like conducting feature at the layer edge of the 2D perovskite provides a different dimension for enhancing the performance of the next-generation optoelectronics and developing innovative nanoelectronics.
Open Access
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