by Yan Xiong,
Ling Xu,
Ping Wu,
Lin Sun,
Guo Xie,
Bin Hu
Bi‐doped MAPbI3 perovskite can simultaneously improve the Seebeck coefficient and electrical conductivity. It not only promotes the charge transport through carrier channels near grain boundaries, but can also passivate the defects, increasing the stability of MASnI3.
Abstract
In this article, the thermoelectric properties of a Bi‐doped CH3NH3PbI3 (MAPbI3) perovskite thin film are studied. Bi‐doped MAPbI3 thin film samples are fabricated, and it is found that Bi doping could greatly enhance the stability and thermoelectric properties of MAPbI3. The Bi dopant located at the grain boundaries to modify the carrier channel near grain boundaries, which is observed via scanning electron microscopy and atomic force microscopy, efficiently reduces ion migration and facilitates charge transport. In addition, the Bi dopant can also passivate the defects in bulk MAPbI3, increasing the polarization effect of MAPbI3 which is demonstrated by the capacitance‐frequency measurement, thus greatly enhancing the mobility of Bi‐doped MAPbI3. In addition, Bi‐doped MAPbI3 leads to grain size reduction; the small size effect not only effectively hinders the MAPbI3's crystal phase transition from the tetragonal phase to the cubic phase, but it could also make the structure of MAPbI3 more stable. Especially, the Seebeck voltage variation of Bi‐doped perovskite was less than that of the undoped one, meaning Bi doping would lead to a much more stable state in MAPbI3 thin films. The results show that Bi‐doped MAPbI3 is a promising approach to develop high stable thermoelectric and photovoltaic properties in organic–inorganic hybrid perovskite materials.
J. Mater. Chem. A, 2019, 7,11886-11894 DOI: 10.1039/C9TA02415H, Paper
Virginia Cuesta, Maida Vartanian, Prateek Malhotra, Subhayan Biswas, Pilar de la Cruz, Ganesh D. Sharma, Fernando Langa A new D–π–A–π–D system, based on selenophene and Zn-porphyrin, is described and studied as a donor in OSCs, presenting a PCE of 9.24%. The content of this RSS Feed (c) The Royal Society of Chemistry
Author(s): Shuyan Shao, Jingjin Dong, Herman Duim, Gert H. ten Brink, Graeme R. Blake, Giuseppe Portale, Maria Antonietta Loi
Abstract
Low power conversion efficiency (PCE) and poor reproducibility are among the main challenges for tin-based perovskite solar cells (HPSCs). The facile formation of tin vacancies and oxidation of the divalent tin cation during the thin film fabrication process are among the causes of these problems, because the tin perovskite layer then becomes p-doped, resulting in significant trap-assisted recombination losses in devices. In this paper, we demonstrate that increasing the crystallinity of the tin perovskite film is an effective way to address the open issues with Sn-based perovskites. We succeed in improving the crystallinity of the 3D formamidinium tin iodide (FASnI3) grains, increasing their size, and perfecting their orientation in the out-of-plane direction by incorporating ethylammonium iodide (EAI) into a 2D/3D tin perovskite film (where 2D is PEA2FASn2I7, PEA = phenylethylammonium). This leads to a decrease of traps and background charge carrier density, and therefore to decreased charge recombination losses in EAx2D/3D based devices, as compared not only to devices based on FASnI3 but also to those based on 2D/3D mixtures. As a consequence, devices using a perovskite layer with composition EA0.082D/3D exhibit much higher PCE (8.4%) and better reproducibility compared to devices based on mixed 2D/3D perovskites (7.7%) and 3D perovskite (4.7%).
by Young‐Jun You,
Chang Eun Song,
Quoc Viet Hoang,
Yoonmook Kang,
Ji Soo Goo,
Doo‐Hyun Ko,
Jae‐Joon Lee,
Won Suk Shin,
Jae Won Shim
Poly[(5,6‐bis(2‐hexyldecyloxy)benzo[c][1,2,5]thiadiazole‐4,7‐diyl)‐alt‐(5,50‐(2,5‐difluoro‐1,4‐phenylene)bis(thiophen‐2‐yl))] (PDTBTBz‐2Fanti)‐based organic photovoltaics (OPVs) show an exceptionally high efficiency of 23.1% under a 1000‐lx light‐emitting diode lamp.
Abstract
The unique electro‐optical features of organic photovoltaics (OPVs) have led to their use in applications that focus on indoor energy harvesters. Various adoptable photoactive materials with distinct spectral absorption windows offer enormous potential for their use under various indoor light sources. An in‐depth study on the performance optimization of indoor OPVs is conducted using various photoactive materials with different spectral absorption ranges. Among the materials, the fluorinated phenylene‐alkoxybenzothiadiazole‐based wide bandgap polymer—poly[(5,6‐bis(2‐hexyldecyloxy)benzo[c][1,2,5]thiadiazole‐4,7‐diyl)‐alt‐(5,50‐(2,5‐difluoro‐1,4‐phenylene)bis(thiophen‐2‐yl))] (PDTBTBz‐2Fanti)‐contained photoactive layer—exhibits a superior spectrum matching with indoor lights, particularly a light‐emitting diode (LED), which results in an excellent power absorption ratio. These optical properties contribute to the state‐of‐the‐art performance of the PDTBTBz‐2Fanti:[6,6]‐phenyl‐C71 butyric acid methyl ester (PC71BM)‐based OPV with an unprecedented high power‐conversion efficiency (PCE) of 23.1% under a 1000 lx LED. Finally, its indoor photovoltaic performance is observed to be better than that of an interdigitated‐back‐contact‐based silicon photovoltaic (PCE of 16.3%).
Remarkable advancement has been made in the efficiency of organic solar cells (OSCs) in recent times, mostly due to novel fused ring electron acceptors (FREAs). Here, structural evolution of FREAs to enhance efficiency is comprehensively discussed. Moreover, recent progress in polymer design, semi‐transparent OSCs, ternary, and tandem OSCs is provided. The challenges and future development of FREAs are briefly addressed.
Abstract
The quest for sustainable energy sources has led to accelerated growth in research of organic solar cells (OSCs). A solution‐processed bulk‐heterojunction (BHJ) OSC generally contains a donor and expensive fullerene acceptors (FAs). The last 20 years have been devoted by the OSC community to developing donor materials, specifically low bandgap polymers, to complement FAs in BHJs. The current improvement from ≈2.5% in 2013 to 17.3% in 2018 in OSC performance is primarily credited to novel nonfullerene acceptors (NFA), especially fused ring electron acceptors (FREAs). FREAs offer unique advantages over FAs, like broad absorption of solar radiation, and they can be extensively chemically manipulated to tune optoelectronic and morphological properties. Herein, the current status in FREA‐based OSCs is summarized, such as design strategies for both wide and narrow bandgap FREAs for BHJ, all‐small‐molecule OSCs, semi‐transparent OSC, ternary, and tandem solar cells. The photovoltaics parameters for FREAs are summarized and discussed. The focus is on the various FREA structures and their role in optical and morphological tuning. Besides, the advantages and drawbacks of both FAs and NFAs are discussed. Finally, an outlook in the field of FREA‐OSCs for future material design and challenges ahead is provided.
J. Mater. Chem. A, 2019, 7,11802-11813 DOI: 10.1039/C9TA03177D, Paper
Shi-Sheng Wan, Xiaopeng Xu, Jin-Liang Wang, Gui-Zhou Yuan, Zhao Jiang, Gao-Yang Ge, Hai-Rui Bai, Zheng Li, Qiang Peng The PCE of 13.68% with the Eloss of 0.49 eV were obtained, which were the highest values obtained to date in binary PSCs with monochlorinated NF-SMAs. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,11764-11770 DOI: 10.1039/C9TA02916H, Paper
Xuping Liu, Jihuai Wu, Qiyao Guo, Yuqian Yang, Hui Luo, Quanzhen Liu, Xiaobing Wang, Xin He, Miaoliang Huang, Zhang Lan A perovskite solar cell with pyrrole doping achieves an optimal power conversion efficiency of 20.07%. The content of this RSS Feed (c) The Royal Society of Chemistry
Xiuxiu Niu, Nengxu Li, Cheng Zhu, Lang Liu, Yizhou Zhao, Yang Ge, Yihua Chen, Ziqi Xu, Yue Lu, Manling Sui, Yujing Li, Alexey Tarasov, Eugene A. Goodilin, Huanping Zhou, Qi Chen The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,12166-12175 DOI: 10.1039/C9TA02566A, Paper
Feng Wang, Ting Zhang, Yafei Wang, Detao Liu, Peng Zhang, Hao Chen, Long Ji, Li Chen, Zhi David Chen, Jiang Wu, Xin Liu, Yanbo Li, Yafei Wang, Shibin Li We developed a “humidity-insensitive antisolvent method” for highly efficient PSCs by steering the crystallization of perovskite precursor films. The content of this RSS Feed (c) The Royal Society of Chemistry
by Dongwei Han,
Yu Xin,
Quan Yuan,
Qifeng Yang,
Yu Wang,
Yang Yang,
Siwei Yi,
Dongying Zhou,
Lai Feng,
Yanqin Wang
Solution‐processed 2D Nb2O5(001) nanosheets (c‐Nb2O5 NS) are prepared and combined with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as an electron transport layer (ETL) for inverted inorganic CsPbI2Br perovskite solar cells (PeSCs) with a high performance. The c‐Nb2O5 NS not only facilitate the electron transport, blocking the hole transport, but also contribute to the defect passivation and retard the iodine ions diffusion toward the Ag electrode.
Herein, solution‐processed 2D Nb2O5(001) nanosheets (c‐Nb2O5 NS) are prepared and combined with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as an electron transport layer (ETL) for inverted inorganic CsPbI2Br perovskite solar cells (PeSCs). The PeSCs with a c‐Nb2O5/PC61BM bilayer ETL yield a high power conversion efficiency (PCE) up to 11.74%, remarkably outperforming the devices with only PC61BM (9.10%) and those with the state‐of‐the‐art ZnO/C60 ETL (10.65%) prepared under the same conditions. More importantly, the nonencapsulated PeSCs with c‐Nb2O5 exhibit a high thermal stability with only 20% PCE loss after 400 h thermal aging at 85 °C. Such an impressive performance and a high stability can be attributed to the introduction of c‐Nb2O5(001) NS with favorable band levels, strong acid nature, and the small lattice fringe spacing along the large lateral (001) surface, which not only facilitate the electron transport, blocking the hole transport, but also contribute to defect passivation and retard the iodine ions diffusion toward the Ag electrode. This study thus provides a deeper insight for the interfacial design in inverted inorganic PeSCs and contributes to PCE improvement in the future.
Antimony selenide (Sb2Se3) thin film solar cells have gained worldwide intense research owing to their suitable bandgap, high absorption coefficient, benign grain boundaries, earth-abundant element constituents and low fabrication cost. It is extremely important to investigate the interface passivation and minimize the carrier recombination to realize high-efficiency Sb2Se3 solar cells. Very little is known, however, about the carrier recombination mechanisms at the interfaces of Sb2Se3 solar cells. Herein, we show that a novel solution-processed SnO2 layer (∼12 nm) incorporated into Sb2Se3 thin film solar cells results in high power conversion efficiency of 7.5%, namely, an improvement of 39% relative to that of the solar cell without SnO2 interfacial layer. Furthermore, the open-circuit voltage (Voc) is the highest ever reported for Sb2Se3 solar cells. These improvements benefit from the better preferred [221] orientation, less bulk and interfacial defects in the Sb2Se3 absorbers, and relatively ideal heterointerfaces due to the SnO2 passivation. This work opens up new routes for the critical importance of interfacial control in Sb2Se3 solar cells, which could be extended to other emerging low-dimensional thin film solar cells.
The power conversion efficiency (PCE) reaches to 12.63% or 12.19% for polymer solar cells (PSCs) based on PM6 or J71 as donor and Br-ITIC as acceptor, respectively. A series of ternary PSCs with two donors were fabricated by combining the merits of the two binary PSCs. The PM6 and J71 prefer to form alloyed donor due to the good compatibility, which is beneficial to finely optimize photon harvesting and phase separation of ternary active layers, leading to simultaneous improvement of short-circuit current density (JSC) and fill factor (FF). The improved JSC and FF can well make up for the slight loss of open-circuit voltage (VOC). The optimized ternary PSCs with 20 wt% J71 in donors achieve a PCE of 14.13% and a FF of 78.4%. More than 11% PCE improvement is achieved by adopting ternary strategy on the basis of two binary PSCs with PCE over 12%, also keeping simple fabrication technology.
Graphical abstract
The optimized ternary PSCs achieve a PCE of 14.13% by incorporating alloyed donor (PBDB-T-2F and J71) with a non-fullerene acceptor Br-ITIC. More than 11% PCE improvement is achieved by employing ternary strategy on the basis of binary PSCs with PCE over 12%, which is mainly attributed to the enhanced photon harvesting and optimized phase separation of the ternary active layer.
by Keqiang Chen,
Qiaohui Zhong,
Wen Chen,
Binghua Sang,
Yingwei Wang,
Tingqiang Yang,
Yueli Liu,
Yupeng Zhang,
Han Zhang
α‐CsPbI3 quantum dots (QDs) are synthesized using mixed ligands (oleic acid (OA), oleylamine (OLA), octanoic acid, and octylamine, C8/C18), which exhibit higher photoluminescence quantum yield (94%) and enhanced stability (>180 days) compared to QDs capped with OA and OLA (C18). The C8/C18‐CsPbI3 QDs‐based solar cell shows enhanced power conversion efficiency (11.87%) when compared with a C18‐CsPbI3 QDs‐based solar cell (7.76%).
Abstract
Cubic phase CsPbI3 (α‐CsPbI3) perovskite quantum dots (QDs) have received extensive attention due to their all‐inorganic composition and suitable band gap (1.73 eV). However, α‐CsPbI3 QDs might convert to δ‐CsPbI3 (orthorhombic phase with indirect band gap of 2.82 eV) due to easy loss of surface ligands. In addition, commonly used long‐chain ligands (oleic acid, OA, and oleylamine, OLA) hinder efficient charge transport in optoelectronic devices. In order to relieve these drawbacks, OA, OLA, octanoic acid, and octylamine are used as capping ligands for synthesizing high‐quality α‐CsPbI3 QDs. The results indicate that these QDs exhibit excellent optical properties and long‐term stability compared to QDs capped only with OA and OLA. Moreover, QDs with shorter ligands exhibit an enhanced charge transport rate, which improves the power conversion efficiency of photovoltaic devices from 7.76% to 11.87%.
by Keqiang Chen,
Qiaohui Zhong,
Wen Chen,
Binghua Sang,
Yingwei Wang,
Tingqiang Yang,
Yueli Liu,
Yupeng Zhang,
Han Zhang
α‐CsPbI3 quantum dots (QDs) are synthesized using mixed ligands (oleic acid (OA), oleylamine (OLA), octanoic acid, and octylamine, C8/C18), which exhibit higher photoluminescence quantum yield (94%) and enhanced stability (>180 days) compared to QDs capped with OA and OLA (C18). The C8/C18‐CsPbI3 QDs‐based solar cell shows enhanced power conversion efficiency (11.87%) when compared with a C18‐CsPbI3 QDs‐based solar cell (7.76%).
Abstract
Cubic phase CsPbI3 (α‐CsPbI3) perovskite quantum dots (QDs) have received extensive attention due to their all‐inorganic composition and suitable band gap (1.73 eV). However, α‐CsPbI3 QDs might convert to δ‐CsPbI3 (orthorhombic phase with indirect band gap of 2.82 eV) due to easy loss of surface ligands. In addition, commonly used long‐chain ligands (oleic acid, OA, and oleylamine, OLA) hinder efficient charge transport in optoelectronic devices. In order to relieve these drawbacks, OA, OLA, octanoic acid, and octylamine are used as capping ligands for synthesizing high‐quality α‐CsPbI3 QDs. The results indicate that these QDs exhibit excellent optical properties and long‐term stability compared to QDs capped only with OA and OLA. Moreover, QDs with shorter ligands exhibit an enhanced charge transport rate, which improves the power conversion efficiency of photovoltaic devices from 7.76% to 11.87%.
by Fan Liu,
Fei Wu,
Zongxiao Tu,
Qiuyan Liao,
Yanbin Gong,
Linna Zhu,
Qianqian Li,
Zhen Li
The different aggregation forms of hole‐transporting materials (HTMs) affect intermolecular charge transfer and hole transporting in achieving highly efficient dopant‐free perovskite solar cells. The combination of twisted periphery groups with planar core units shows an efficient approach to regulate the state of molecular aggregation after a systematical investigation of 6,12‐dihydroindeno[1,2‐b]fluorine (IDF)‐HTMs with the same IDF core and the different periphery groups.
Abstract
Although several hole‐transporting materials (HTMs) have been designed to obtain perovskite solar cells (PSCs) devices with high performance, the dopant‐free HTMs for efficient and stable PSCs remain rare. Herein, a rigid planar 6,12‐dihydroindeno[1,2‐b]fluorine (IDF) core with different numbers of bulky periphery groups to construct dopant‐free HTMs of IDF‐SFXPh, IDF‐DiDPA, and IDF‐TeDPA is modified. Thanks to the contributions of the planar IDF core and the twisted SFX periphery groups, the dopant‐free IDF‐SFXPh‐based PSCs device achieves a device performance of 17.6%, comparable to the doped 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD)‐based device (17.6%), with much enhanced device stability under glovebox and ambient conditions.
by Hao Zhang,
Yongzhen Wu,
Chao Shen,
Erpeng Li,
Chenxu Yan,
Weiwei Zhang,
He Tian,
Liyuan Han,
Wei‐Hong Zhu
A specific bidentate molecule, 2‐mercaptopyridine, is demonstrated to substantially enhance anchoring strength at surface of metal halide perovskites, which improves the passivation efficacy and stability synchronously relative to monodentate counterparts. The highly stable bidentate anchoring based passivation on CH3NH3PbI3 not only advances power conversion efficiency from 18.35% to 20.28%, but also leads to a champion lifetime in humid air.
Abstract
Chemical passivation is an effective approach to suppress the grain surface dominated charge recombination in perovskite solar cells (PSCs). However, the passivation effect is usually labile on perovskite crystal surface since most passivating agents are weakly anchored. Here, the use of a bidentate molecule, 2‐mercaptopyridine (2‐MP), to increase anchoring strength for improving the passivation efficacy and stability synchronously is demonstrated. Compared to monodentate counterparts of pyridine and p‐toluenethiol, 2‐MP passivation on CH3NH3PbI3 film results in twofold improvement of photoluminescence lifetime and remarkably enhanced tolerance to chlorobenzene washing and vacuum heating, which improve the power conversion efficiency of n–i–p planar structured PSCs from 18.35% to 20.28%, with open‐circuit voltage approaching 1.18 V. Moreover, the CH3NH3PbI3 films passivated with 2‐MP exhibit unprecedented humid‐stability that they can be exposed to saturated humidity for at least 5 h, mainly due to the passivation induced surface deactivation, which renders the unencapsulated devices retaining 93% of the initial efficiency after 60 days aging in air with relative humidity of 60–70%.
J. Mater. Chem. A, 2019, 7,12292-12302 DOI: 10.1039/C9TA00715F, Paper
Diego Di Girolamo, M. Ibrahim Dar, Danilo Dini, Lorenzo Gontrani, Ruggero Caminiti, Alessandro Mattoni, Michael Graetzel, Simone Meloni Humidity enhances the crystallinity of CpPbBr3 perovskite films for short exposure times and degrades them for long exposure times. The content of this RSS Feed (c) The Royal Society of Chemistry
by Jingjing Tian,
Qifan Xue,
Xiaofeng Tang,
Yuxuan Chen,
Ning Li,
Zhicheng Hu,
Tingting Shi,
Xin Wang,
Fei Huang,
Christoph J. Brabec,
Hin‐Lap Yip,
Yong Cao
The efficiency and photostability of all‐inorganic mixed‐halide perovskite solar cells (PVSCs) can be simultaneously enhanced by introducing an amino‐functionalized polymer PN4N as a novel cathode interlayer and dopant‐free PDCBT hole‐transporting layer. The favorable interaction between perovskite crystal and PN4N/PDCBT can effectively improve CsPbI2Br film quality, with power conversion efficiency over 16%.
Abstract
A synergic interface design is demonstrated for photostable inorganic mixed‐halide perovskite solar cells (PVSCs) by applying an amino‐functionalized polymer (PN4N) as cathode interlayer and a dopant‐free hole‐transporting polymer poly[5,5′‐bis(2‐butyloctyl)‐(2,2′‐bithiophene)‐4,4′‐dicarboxylate‐alt‐5,5′‐2,2′‐bithiophene] (PDCBT) as anode interlayer. First, the interfacial dipole formed at the cathode interface reduces the workfunction of SnO2, while PDCBT with deeper‐lying highest occupied molecular orbital (HOMO) level provides a better energy‐level matching at the anode, leading to a significant enhancement in open‐circuit voltage (Voc) of the PVSCs. Second, the PN4N layer can also tune the surface wetting property to promote the growth of high‐quality all‐inorganic perovskite films with larger grain size and higher crystallinity. Most importantly, both theoretical and experimental results reveal that PN4N and PDCBT can interact strongly with the perovskite crystal, which effectively passivates the electronic surface trap states and suppresses the photoinduced halide segregation of CsPbI2Br films. Therefore, the optimized CsPbI2Br PVSCs exhibit reduced interfacial recombination with efficiency over 16%, which is one of the highest efficiencies reported for all‐inorganic PVSCs. A high photostability with a less than 10% efficiency drop is demonstrated for the CsPbI2Br PVSCs with dual interfacial modifications under continuous 1 sun equivalent illumination for 400 h.
by Waqas Siddique Subhani,
Kai Wang,
Minyong Du,
Xiuli Wang,
Shengzhong (Frank) Liu
To optimize inorganic perovskite based solar cells, a lanthanide halide is employed to modify the electron transport layer/perovskite interface and form a gradient energy band, which can restrain the charge recombination at the interface and inside the perovskite. Eventually, an efficiency as high as 10.88% is obtained, representing the highest efficiency of CsPbIBr2 perovskite solar cells.
Abstract
Inorganic cesium lead halide perovskite solar cells (PSCs) have received enormous attention due to their excellent stability compared with that of their organic–inorganic counterparts. However, the lack of optimization strategies leads the inorganic PSCs to suffer from low efficiency arising from significant recombination. To overcome this dilemma, a surface modification of the electron transport layer (ETL)/perovskite interface is undertaken by using SmBr3 to improve the crystallization and morphology of the perovskite layer for enhanced ETL/perovskite interface interaction. Encouragingly, a gradient energy band is created at the interface with an outstanding hole blocking effect. As a result, both the charge recombination occurring at the interface and the nonradiative recombination inside the perovskite are suppressed, and, simultaneously, the charge extraction is improved successfully. Therefore, the power conversion efficiency of the CsPbIBr2 PSCs is increased to as high as 10.88% under one sun illumination, which is 30% higher than its counterparts without the modification. It is logically inferred that this valuable optimization strategy can be extended to other analogous structures and materials.
Energy Environ. Sci., 2019, 12,1634-1647 DOI: 10.1039/C9EE00077A, Paper
Felix Lang, Marko Jošt, Jürgen Bundesmann, Andrea Denker, Steve Albrecht, Giovanni Landi, Heinz-Christoph Neitzert, Jörg Rappich, Norbert H. Nickel Although highly energetic proton irradiation forms localized trap states in triple cation perovskites, solar cells possess exceptional radiation hardness. The content of this RSS Feed (c) The Royal Society of Chemistry
Perovskite Nanocrystals CsPbX3 (X=Cl, Br, and I) nanocrystals have been prepared that give near unity red, green, and blue photoluminescence quantum yields, as demonstrated by S. Baitalik, N. Pradhan, and co‐workers in their Communication on https://doi.org/10.1002/anie.201900374page 5552 ff.
by Fan Liu,
Fei Wu,
Zongxiao Tu,
Qiuyan Liao,
Yanbin Gong,
Linna Zhu,
Qianqian Li,
Zhen Li
The different aggregation forms of hole‐transporting materials (HTMs) affect intermolecular charge transfer and hole transporting in achieving highly efficient dopant‐free perovskite solar cells. The combination of twisted periphery groups with planar core units shows an efficient approach to regulate the state of molecular aggregation after a systematical investigation of 6,12‐dihydroindeno[1,2‐b]fluorine (IDF)‐HTMs with the same IDF core and the different periphery groups.
Abstract
Although several hole‐transporting materials (HTMs) have been designed to obtain perovskite solar cells (PSCs) devices with high performance, the dopant‐free HTMs for efficient and stable PSCs remain rare. Herein, a rigid planar 6,12‐dihydroindeno[1,2‐b]fluorine (IDF) core with different numbers of bulky periphery groups to construct dopant‐free HTMs of IDF‐SFXPh, IDF‐DiDPA, and IDF‐TeDPA is modified. Thanks to the contributions of the planar IDF core and the twisted SFX periphery groups, the dopant‐free IDF‐SFXPh‐based PSCs device achieves a device performance of 17.6%, comparable to the doped 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD)‐based device (17.6%), with much enhanced device stability under glovebox and ambient conditions.
by Fang Qian,
Shihao Yuan,
Yuan Cai,
Yu Han,
Huan Zhao,
Jie Sun,
Zhike Liu,
Shengzhong (Frank) Liu
A novel surface passivation of a perovskite surface is reported using the polyfluoro organic compound tris(pentafluorophenyl)boron (TPFPB), which can yield large grains, reduced defect densities, and improved charge transport and phase stability for the perovskite film. Using this strategy, a champion perovskite solar cell achieves a high power conversion efficiency of 21.6% as well as significantly improved air and light stabilities.
In planar perovskite solar cells (PSCs), defect‐induced recombination at the interface between the perovskite and hole transport layer (HTL) leads to a large potential loss and performance deterioration. Therefore, an effective method for improving interfacial properties is critical to boost the performance and stability of PSCs. Herein, a novel surface engineering technology is reported for passivating the perovskite surface with the polyfluoro organic compound tris(pentafluorophenyl)boron (TPFPB), which can yield large perovskite grains, reduced defect densities, and improved charge transport and phase stability for the perovskite film, and enhanced power conversion efficiency (PCE) and stability for PSCs. Using this strategy, a champion FA0.85MA0.15PbI3 perovskite cell achieves a high PCE of 21.6% as well as significantly improved air and light stabilities. This work demonstrates that TPFPB is a promising material for crystallization control and defect passivation and paves a new path for mitigating defects and further increasing the performance of planar PSCs.
by Changlei Wang,
Zhaoning Song,
Dewei Zhao,
Rasha A. Awni,
Chongwen Li,
Niraj Shrestha,
Cong Chen,
Xinxing Yin,
Dengbing Li,
Randy J. Ellingson,
Xingzhong Zhao,
Xiaofeng Li,
Yanfa Yan
A block copolymer F127 passivation strategy in conjunction with the solvent annealing process significantly enhances the performance and stability of planar perovskite solar cells. Hydrophilic tails of F127 passivate defects at grain boundaries through hydrogen bonding, whereas the dangling hydrophobic groups suppress perovskite decomposition against moisture and heat.
Organic–inorganic metal halide perovskite solar cells (PSCs) exhibit excellent photovoltaic performance but have the drawbacks of instabilities against moisture and heat due to the inherent hydroscopic nature and volatility of their organic components. Herein, it is reported that using the block copolymer F127 as the passivation reagent in conjunction with the solvent annealing process can efficiently improve the performance and stability of corresponding organic–inorganic PSCs. It is anticipated that the hydrophilic poly(ethylene oxide) tails of F127 polymers connect with contiguous perovskite crystals and passivate defects at perovskite grain boundaries, whereas the dangling hydrophobic poly(phenyl oxide) centers suppress perovskite decomposition caused by moisture and heat. After the optimization of the F127 additive, planar PSCs with champion power conversion efficiencies of 21.01% and 18.71% are achieved on rigid and flexible substrates, respectively. The F127 passivation strategy provides an effective approach for fabricating high‐efficiency and stable PSCs.
by Bao Tu,
Yangfan Shao,
Wei Chen,
Yinghui Wu,
Xin Li,
Yanling He,
Jiaxing Li,
Fangzhou Liu,
Zheng Zhang,
Yi Lin,
Xiaoqi Lan,
Leiming Xu,
Xingqiang Shi,
Alan Man Ching Ng,
Haifeng Li,
Lung Wa Chung,
Aleksandra B. Djurišić,
Zhubing He
An n‐doping of SnO2 is successfully realized through the use of the triphenylphosphine‐oxide molecule, where electrons are revealed to be transferred from the R3P+O− σ‐bond to the peripheral tin atoms and delocalized. That novel effect enlarges the built‐in‐field from 0.01 to 0.07 eV and reduces the energy‐barrier from 0.55 to 0.39 eV at the SnO2–perovskite interface enabling a device conversion‐efficiency from 19.01% to 20.69%.
Abstract
Molecular doping of inorganic semiconductors is a rising topic in the field of organic/inorganic hybrid electronics. However, it is difficult to find dopant molecules which simultaneously exhibit strong reducibility and stability in ambient atmosphere, which are needed for n‐type doping of oxide semiconductors. Herein, successful n‐type doping of SnO2 is demonstrated by a simple, air‐robust, and cost‐effective triphenylphosphine oxide molecule. Strikingly, it is discovered that electrons are transferred from the R3P+O−σ‐bond to the peripheral tin atoms other than the directly interacted ones at the surface. That means those electrons are delocalized. The course is verified by multi‐photophysical characterizations. This doping effect accounts for the enhancement of conductivity and the decline of work function of SnO2, which enlarges the built‐in field from 0.01 to 0.07 eV and decreases the energy barrier from 0.55 to 0.39 eV at the SnO2/perovskite interface enabling an increase in the conversion efficiency of perovskite solar cells from 19.01% to 20.69%.
by Huiliang Sun,
Yumin Tang,
Chang Woo Koh,
Shaohua Ling,
Ruizhi Wang,
Kun Yang,
Jianwei Yu,
Yongqiang Shi,
Yingfeng Wang,
Han Young Woo,
Xugang Guo
Ring fusion and backbone fluorination yield a novel ladder‐type building block f‐FBTI2, a desirable “stronger acceptor” for enabling n‐type electron‐acceptor polymers. The resulting polymer semiconductor f‐FBTI2‐T shows an excellent power conversion efficiency of 8.1% with a very small energy loss of 0.53 eV in all‐polymer solar cell devices.
Abstract
A novel imide‐functionalized arene, di(fluorothienyl)thienothiophene diimide (f‐FBTI2), featuring a fused backbone functionalized with electron‐withdrawing F atoms, is designed, and the synthetic challenges associated with highly electron‐deficient fluorinated imide are overcome. The incorporation of f‐FBTI2 into polymer affords a high‐performance n‐type semiconductor f‐FBTI2‐T, which shows a reduced bandgap and lower‐lying lowest unoccupied molecular orbital (LUMO) energy level than the polymer analog without F or with F‐functionalization on the donor moiety. These optoelectronic properties reflect the distinctive advantages of fluorination of electron‐deficient acceptors, yielding “stronger acceptors,” which are desirable for n‐type polymers. When used as a polymer acceptor in all‐polymer solar cells, an excellent power conversion efficiency of 8.1% is achieved without any solvent additive or thermal treatment, which is the highest value reported for all‐polymer solar cells except well‐studied naphthalene diimide and perylene diimide‐based n‐type polymers. In addition, the solar cells show an energy loss of 0.53 eV, the smallest value reported to date for all‐polymer solar cells with efficiency > 8%. These results demonstrate that fluorination of imide‐functionalized arenes offers an effective approach for developing new electron‐deficient building blocks with improved optoelectronic properties, and the emergence of f‐FBTI2 will change the scenario in terms of developing n‐type polymers for high‐performance all‐polymer solar cells.
by Sawanta S. Mali,
Jyoti V. Patil,
Hyungjin Kim,
HyunHoon Kim,
Chang Kook Hong
Controlling the retarding reaction process enhances perovskite crystal growth, resulting in >20% efficiency. The dual retarding process enables large perovskite thin film grain size, which facilitates enhanced photovoltaic performance.
Abstract
Mixed‐cation perovskite solar cells (PSCs) have become of enormous interest because of their excellent efficiency, which is now crossing 23.7%. Their broader absorption, relatively high stability with low fabrication cost compared to conventional single phase ABX3 perovskites (where A: organic cation; B: divalent metal ion; and X: halide anion) are key properties of mixed‐halide mixed‐cation perovskites. However, the controlling reaction rate and formation of extremely dense, textured, smooth, and large grains of perovskite layer is a crucial task in order to achieve highly efficient PSCs. Herein, a new simple dual‐retarded reaction processing (DRP) method is developed to synthesize a high‐quality mixed‐cation (FAPbI3)0.85(MAPbBr3)0.15 (where MAPbBr3 stands for methylammonium lead bromide and FAPbI3 stands for formamidinium lead iodide) perovskite thin film via intermediate phase and incorporation of nitrogen‐doped reduced graphene oxide (N‐rGO). The reaction rate is retarded via two steps: first the formation of intermediate phase and second the interaction of the nitrogen groups on N‐rGO with hydrogen atoms from formamidinium cations. This DRP process allows for the fabrication of PSCs with maximum conversion efficiency higher than 20.3%.
Open Access
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