21 Apr 00:55
Energy Environ. Sci., 2021, 14,3010-3018
DOI: 10.1039/D0EE03387A, Communication
Jiang Huang, Dan Zhao, Zifan Dou, Qingshan Fan, Na Li, Shuihai Peng, Haoran Liu, Yadong Jiang, Junsheng Yu, Chang-Zhi Li
Highly efficient organic solar cells (OSCs) are demonstrated with the new design of column-patterned microcavity, which allows enhancing the external quantum efficiencies of both visible and near-infrared range of indium tin oxide free OSCs.
The content of this RSS Feed (c) The Royal Society of Chemistry
21 Apr 00:54
Energy Environ. Sci., 2021, 14,2314-2321
DOI: 10.1039/D0EE03490H, Paper
Yanan Wei, Jianwei Yu, Linqing Qin, Hao Chen, Xiaoxi Wu, Zhixiang Wei, Xin Zhang, Zuo Xiao, Liming Ding, Feng Gao, Hui Huang
Quantitative relationship between the protective factor (δ) and PCE of stacked structures of OSC with a record PCE of 17.52% is proposed to understand the mechanism and provide a guideline for solvent choices of eco-friendly solvent protection method.
The content of this RSS Feed (c) The Royal Society of Chemistry
20 Apr 13:01
by Haolin Liu, Wenjie Fan, Haoran Lv, Wenzhe Zhang, Jing Shi, Minghua Huang, Shuai Liu, and Huanlei Wang
ACS Applied Energy Materials
DOI: 10.1021/acsaem.0c02859
20 Apr 06:08
J. Mater. Chem. A, 2021, 9,6775-6789
DOI: 10.1039/D0TA11197J, Perspective
Vikas Sharma, Josh D. B. Koenig, Gregory C. Welch
This perspective showcases new materials designs for perylene diimide based non-fullerene acceptors towards high performance photovoltaic devices.
The content of this RSS Feed (c) The Royal Society of Chemistry
27 Feb 06:47
by Pengjie Hang,
Jiangsheng Xie,
Chenxia Kan,
Biao Li,
Yiqiang Zhang,
Pingqi Gao,
Deren Yang,
Xuegong Yu
Over 23% efficiency is achieved using a stabilized phenyl‐C61‐butyric acid methyl ester (PCBM):bathophenanthroline (Bphen) interlayer in SnO2‐based perovskite solar cells, which can retain over 92% of their initial efficiency after 1000 h continuous illumination of maximum power point tracking at 60 °C.
Abstract
It is crucial to make perovskite solar cells sustainable and have a stable operation under natural light soaking before they become commercially acceptable. Herein, a small amount of the small molecule bathophenanthroline (Bphen) is introduced into [6,6]‐phenyl‐C61‐butyric acid methyl ester and it is found that Bphen can stabilize the C60‐cage well through formation of much more thermodynamically stable charge‐transfer complexes. Such a strengthened complex is used as an interlayer at the in‐light perovskite/SnO2 side to achieve a champion device with efficiency of 23.09% (certified 22.85%). Most importantly, the stability of the resulting devices can be close to meeting the requirements of the International Electrotechnical Commission 61215 standard under simulated UV preconditioning and light‐soaking testing. They can retain over 95% and 92% of their initial efficiencies after 1100 h UV irradiation and 1000 h continuous illumination of maximum power point tracking at 60 °C, respectively.
27 Feb 05:53
by Xiaomin Guo,
Peisen Yuan,
Jianzhong Fan,
Xianfeng Qiao,
Dezhi Yang,
Yanfeng Dai,
Qian Sun,
Anjun Qin,
Ben Zhong Tang,
Dongge Ma
The efficient spin transition between a high‐lying excited triplet state and the lowest excited singlet state in aggregation‐induced emission materials is demonstrated by magnetic field effects. A highly efficient deep‐blue aggregation‐induced emission (AIE)‐based organic light‐emitting diode (OLED) is achieved by further regulating utilization of excitons, which shows an excellent external quantum efficiency of 10.2%, low efficiency roll‐off, and a high brightness of 16 817 cd m−2.
Abstract
Aggregation‐induced emission (AIE) materials are attractive for achieving highly efficient nondoped organic light‐emitting diodes (OLEDs) owing to their strong luminescence in the solid state. However, the electroluminescence efficiency of most AIE‐based OLEDs remains low owing to the waste of triplet excitons. Here, using theoretical calculations, photophysical dynamics, and magnetoluminescence measurements, the spin conversion process is demonstrated between the high‐lying triplet state (T
n
) and the lowest excited singlet state (S1) in AIE materials. Moreover, the relative positions of T
n
(n < 4) and S1 are shown to have a significant impact on the spin‐conversion efficiency, thus influencing the harvesting of triplet excitons and the device efficiency. Finally, by selecting an upconversion material with an appropriate energy level for further utilizing the triplet excitons, a deep‐blue fluorescent OLED with CIE coordinates of (0.15, 0.08), a maximum external quantum efficiency of 10.2%, low efficiency roll‐off, and a high brightness of 16817 cd m−2 is developed. This is one of the most efficient deep‐blue OLEDs based on AIE materials reported so far. These findings also provide new insights into the design of more efficient AIE molecules and corresponding OLEDs by managing high‐lying triplet excitons.
30 Jan 08:07
by Qiannan He,
Wangping Sheng,
Ming Zhang,
Guodong Xu,
Peipei Zhu,
Huotian Zhang,
Zhaoyang Yao,
Feng Gao,
Feng Liu,
Xunfan Liao,
Yiwang Chen
The underlying mechanism of 1, 8‐diiodooctane in morphology evolution is unveiled in bulk heterojunction and pseudoplanar heterojunction (PPHJ) organic solar cells (OSCs). A high‐performance PPHJ OSC is achieved by elaborately regulating the PPHJ morphology with a more balanced crystallinity factor. These results offer a deep insight into morphology regulation, which can guide the optimization of device performance.
Abstract
Additives treatment is as a very effective strategy to optimize bulk heterojunction (BHJ) morphology. However, the inherent working mechanism of this strategy still lacks systematical investigations in non‐fullerene‐acceptors‐based organic solar cells (OSCs). Herein, a series of BHJ and pseudo‐planar heterojunction (PPHJ) OSCs using PM6 and IT‐4F as the electron donor/acceptor pair, are developed to unveil the promoting effect of solvent additive 1, 8‐diiodooctane (DIO) on active layer morphologies and device performance. The study clearly demonstrates that DIO can increase the crystallinity of IT‐4F significantly, while it has less impact on PM6. It is notable that a new efficiency‐determining crystalline balanced factor (CCLpolymer/CCLacceptor) is put forward, indicating that the more balanced CCLpolymer/CCLacceptor results in more balanced charge mobility and much better short‐circuit current densities (J
sc) and fill factors (FF) of OSCs. The PPHJ blend film of PM6/IT‐4F(DIO) exhibits enhanced crystallinity with more balanced CCL and favorable hierarchical distribution morphology, contributing to a champion efficiency of 13.70% with a record J
sc of 20.98 mA cm−2 and a remarkable FF of 75.9%. This work not only reveals the underlying mechanism of DIO caused morphology evolution, but also achieves highly efficient PPHJ OSCs with superior thermal stability by elaborately controlling the morphology of PPHJ film.
30 Jan 08:06
by Ardalan Armin,
Wei Li,
Oskar J. Sandberg,
Zuo Xiao,
Liming Ding,
Jenny Nelson,
Dieter Neher,
Koen Vandewal,
Safa Shoaee,
Tao Wang,
Harald Ade,
Thomas Heumüller,
Christoph Brabec,
Paul Meredith
Organic photovoltaics have long promised low embodied energy, low cost solar power but have yet to make the commercial transition. Recent advances in efficiencies are potentially about to change this status‐quo, driven by a new class of semiconductors called the non‐fullerene electron acceptors. The emergence of these materials is reviewed, and perspectives provided as to future challenges and performance.
Abstract
Organic solar cells are composed of electron donating and accepting organic semiconductors. Whilst a significant palette of donors has been developed over three decades, until recently only a small number of acceptors have proven capable of delivering high power conversion efficiencies. In particular the fullerenes have dominated the landscape. In this perspective, the emergence of a family of materials–the non‐fullerene acceptors (NFAs) is described. These have delivered a discontinuous advance in cell efficiencies, with the significant milestone of 20% now in sight. Intensive international efforts in synthetic chemistry have established clear design rules for molecular engineering enabling an ever‐expanding number of high efficiency candidates. However, these materials challenge the accepted wisdom of how organic solar cells work and force new thinking in areas such as morphology, charge generation and recombination. This perspective provides a historical context for the development of NFAs, and also addresses current thinking in these areas plus considers important manufacturability criteria. There is no doubt that the NFAs have propelled organic solar cell technology to the efficiencies necessary for a viable commercial technology–but how far can they be pushed, and will they also deliver on equally important metrics such as stability?
30 Jan 08:06
by Muhammad Ahsan Saeed,
Sang Hyeon Kim,
Hyeok Kim,
Jiaen Liang,
Han Young Woo,
Tae Geun Kim,
He Yan,
Jae Won Shim
Research on indoor organic photovoltaics (OPVs) over the last five years is discussed. Focusing on the indoor environment (much lower luminance, diverse emission spectra, etc.), reported photoactive layer materials are discussed. Then, the efforts to improve indoor OPV performance by utilizing synergistic parasitic resistance and optical modulation are described. Finally, a description of the relevant optical simulation methods is provided.
Abstract
Recently, indoor organic photovoltaics (OPVs) has attracted substantial research attention, due to the emergence of self‐powered electronic devices for Internet‐of‐Things (IoT) applications. This progress report discusses recent developments in indoor OPVs, focusing on the strategic role of synergistic parasitic resistance in suppressing the leakage current to achieve high indoor efficiencies. Moreover, an underexplored area is presented, namely the impact of optical modulation on enhancing light absorption in indoor OPVs. First, the main advances in material design for indoor OPVs are briefly presented. This is followed by detailed discussions of the crucial strategies, including interfacial engineering, the effect of photoactive layer thickness, and the effectiveness of transparent conducting electrodes for improving the OPV performance. Overall, this review highlights that understanding the indispensable role of parasitic resistance under dim light conditions may provide new opportunities for developing efficient indoor OPVs for practical applications. Finally, after summarizing recent progress in indoor OPVs, a critical perspective is provided.
30 Jan 08:05
by Joel Luke,
Luiza Corrêa,
Jair Rodrigues,
Juliana Martins,
Matyas Daboczi,
Diego Bagnis,
Ji‐Seon Kim
Organic solar cells (OSCs) outperform other technologies at low‐light intensities providing an exciting opportunity for commercialization. Previous OSC low‐light studies utilize non‐scalable materials or methods unsuitable for commercialization. Scalable materials are used to highlight the current performance of commercially relevant low‐light OSCs. The effect of parasitic resistance and a light‐soaking effect that is critical for low‐light performance are also investigated.
Abstract
Low‐light applications provide an exciting market opportunity for organic solar cells (OSCs). However, so far, studies have only considered OSCs of limited commercial viability. Herein, the applicability of a fully‐scalable, flexible, inverted non‐fullerene acceptor (NFA) containing OSC is demonstrated by showing its superior performance to silicon under low‐light, achieving 40 µW cm−2 maximum power output at 1300 lx illumination. The effect of parasitic resistance and dark current on low‐light performance are identified. Furthermore, an atmosphere sensitive light‐soaking (LS) effect, critical for low‐light performance and resulting in undesirable S‐shaped current‐voltage characteristics, is analyzed. By employing different interlayers and photoactive layers (PALs) the origin of this LS effect is identified as poor electron extraction at the electron transport layer (ETL)/PAL interface when the common ETL ZnO is used. Two strategies are implemented to overcome the LS effect: replacement of ZnO with SnO2 nanoparticles to reduce ETL sub‐gap electron trap states or tuning the NFA energy levels to optimize interfacial energetics. Finally, the commercial viability of these LS‐free devices is demonstrated by fabricating fully printed large‐area modules (21.6 cm2) achieving a maximum power output of 17.2 µW cm−2, providing the most relevant example of the currently obtainable performance in commercial low‐light OSCs.
30 Jan 08:03
by Jinzhao Li,
Janardan Dagar,
Oleksandra Shargaieva,
Marion A. Flatken,
Hans Köbler,
Markus Fenske,
Christof Schultz,
Bert Stegemann,
Justus Just,
Daniel M. Többens,
Antonio Abate,
Rahim Munir,
Eva Unger
The addition of the correct amounts of dimethyl sulfoxide (DMSO) with 2‐methoxyethanol (2‐ME) perovskite precursor ink is a crucial step toward reproducible slot‐die coatings and highly efficient perovskite solar cells. Through observing the drying process of 2ME‐DMSO inks from in situ X‐ray diffraction experiments, it is demonstrated that 11.77 mol% DMSO favorably affects thin film growth.
Abstract
Solar cells incorporating metal‐halide perovskite (MHP) semiconductors are continuing to break efficiency records for solution‐processed solar cell devices. Scaling MHP‐based devices to larger area prototypes requires the development and optimization of scalable process technology and ink formulations that enable reproducible coating results. It is demonstrated that the power conversion efficiency (PCE) of small‐area methylammonium lead iodide (MAPbI3) devices, slot‐die coated from a 2‐methoxy‐ethanol (2‐ME) based ink with dimethyl‐sulfoxide (DMSO) used as an additive depends on the amount of DMSO and age of the ink formulation. When adding 12 mol% of DMSO, small‐area devices of high performance (20.8%) are achieved. The effect of DMSO content and age on the thin film morphology and device performance through in situ X‐ray diffraction and small‐angle X‐ray scattering experiments is rationalized. Adding a limited amount of DMSO prevents the formation of a crystalline intermediate phase related to MAPbI3 and 2‐ME (MAPbI3‐2‐ME) and induces the formation of the MAPbI3 perovskite phase. Higher DMSO content leads to the precipitation of the (DMSO)2MA2Pb3I8 intermediate phase that negatively affects the thin‐film morphology. These results demonstrate that rational insights into the ink composition and process control are critical to enable reproducible large‐scale manufacturing of MHP‐based devices for commercial applications.
30 Jan 08:03
by Wei Gao,
Huiting Fu,
Yuxiang Li,
Francis Lin,
Rui Sun,
Ziang Wu,
Xin Wu,
Cheng Zhong,
Jie Min,
Jingdong Luo,
Han Young Woo,
Zonglong Zhu,
Alex K.‐Y. Jen
Conformation effects of Y6‐type acceptors are systematically studied based on asymmetric design strategies. Z‐shape and W‐shape conformations‐based acceptors can help reduce energy loss in devices through significantly suppressed nonradiative energy loss. Benefiting from the high open‐circuit voltage of BP5T‐4F in the devices, ternary organic solar cells based on PM6:BP5T‐4F:CH1007 achieve a 17.2% efficiency.
Abstract
Y6, as a state‐of‐the‐art nonfullerene acceptor (NFA), is extensively optimized by modifying its side chains and terminal groups. However, the conformation effects on molecular properties and photovoltaic performance of Y6 and its derivatives have not yet been systematically studied. Herein, three Y6 analogs, namely, BP4T‐4F, BP5T‐4F, and ABP4T‐4F, are designed and synthesized. Owing to the asymmetric molecular design strategies, three representative molecular conformations for Y6‐type NFAs are obtained through regulating the lateral thiophene orientation of the fused core. It is found that conformation adjustment imposes comprehensive effects on the molecular properties in neat and blend films of these NFAs. As a result, organic solar cells (OSCs) fabricated with PM6:BP4T‐4F, PM6:BP5T‐4F, and PM6:ABP4T‐4F show high power conversion efficiency of 17.1%, 16.7%, and 15.2%, respectively. Interestingly, these NFAs with different conformations also show reduced energy loss (E
loss) in devices via gradually suppressed nonradiative E
loss. Moreover, by employing a selenium‐containing analog, CH1007, as the complementary third component, ternary OSCs based on PM6:BP5T‐4F:CH1007 (1:1.02:0.18) achieve a 17.2% efficiency. This work helps shed light on engineering the molecular conformation of NFAs to achieve high efficiency OSCs with reduced voltage loss.
30 Jan 08:02
by Yaokai Li,
Chengliang He,
Lijian Zuo,
Feng Zhao,
Lingling Zhan,
Xin Li,
Ruoxi Xia,
Hin‐Lap Yip,
Chang‐Zhi Li,
Xu Liu,
Hongzheng Chen
High‐performance organic semi‐transparent photovoltaic (ST‐OPV) devices are achieved by improving the light‐absorbing selectivity, that is, the light‐absorbing capability in invisible regions and light transmission in the visible region. Systematic optimization, including developing a numerical method for photo‐active layer screening, interface engineering, and optical manipulation, enables high‐performance ST‐OPVs with the best light utilization efficiency of 4.1%, ranking among the highest for ST‐OPVs.
Abstract
Semi‐transparent organic photovoltaics (ST‐OPVs) are promising solar windows for building integration. Improving the light‐absorbing selectivity, that is, transmitting the visible photons while absorbing the invisible ones, is a key step toward high‐performance ST‐OPV. To achieve this goal, the optical properties of the active layer, transparent electrode, and capping layer are comprehensively tailored, and a highly efficient ST‐OPV with good absorbing selectivity is demonstrated. First, a numerical method is established to quantify the absorbing selectivity of materials and devices, based on which, an infrared absorbing non‐fullerene acceptor, that is, H3, is selected among a large pool of photo‐active materials. Second, an ultra‐smooth transparent thin Ag layer with small granule size is developed via polyethylenimine wetting, which alleviates light scattering and improves the electric properties for ST‐OPV. Finally, as guided by optical simulation, a TeO2 capping layer is deposited on top of the ultra‐thin Ag to further improve the light‐absorbing selectivity. As a result, the light utilization efficiency is significantly improved to 3.95 ± 0.02% (best ≈4.06%), with a good color rendering index of 76.85. These results make it one of the best among color‐neutral ST‐OPVs. This work stresses the importance of manipulating the light‐absorbing selectivity for high‐performance ST‐OPVs.
30 Jan 08:01
by Seulki Song,
Eun Young Park,
Boo Soo Ma,
Dong Jun Kim,
Helen Hejin Park,
Young Yun Kim,
Seong Sik Shin,
Nam Joong Jeon,
Taek‐Soo Kim,
Jangwon Seo
4‐Dimethylaminopyridine (DMAP) is introduced to develop a facile technique for selectively passivating grain boundaries (GB) and controlling the topographical boundary of perovskite surfaces near GBs. A power conversion efficiency of 22.4% is achieved for a planar perovskite solar cell with DMAP treatment and the device stability under damp‐heat and light irradiation is improved.
Abstract
Recent progress in highly efficient perovskite solar cells (PSCs) has been made by virtue of interfacial engineering on 3D perovskite surfaces for their defect control, however, the structural stability of the modified interface against external stimuli still remains unresolved. Herein, 4‐dimethylaminopyridine (DMAP) is introduced to develop a facile technique for selectively passivating the grain boundary (GB) and controlling the topographical boundary of the perovskite surface near the GB. Through the surface treatment of DMAP, strongly bound DMAP crystals are selectively formed at the GB, which serves two functions: nonradiative recombination at GB is effectively reduced by healing the uncoordinated Pb2+ while adhesion strength between the perovskite and the poly(triaryl amine) (PTAA) polymer is significantly enhanced by a mechanical interlock effect. A planar PSC with DMAP treatment exhibits a champion power conversion efficiency of 22.4%, which is not only much higher than the 20.04% observed for a nontreated control device, but also the highest among the planar PSCs using PTAA polymers as a hole transport material. Furthermore, the use of DMAP leads to a substantial improvement in the device stability under damp‐heat test and light irradiation.
30 Jan 08:01
by Hao‐Cheng Wang,
Pei Cheng,
Shaun Tan,
Chung‐Hao Chen,
Bin Chang,
Cheng‐Si Tsao,
Li‐Yin Chen,
Chung‐An Hsieh,
Yu‐Che Lin,
Hao‐Wen Cheng,
Yang Yang,
Kung‐Hwa Wei
In typical semitransparent organic photovoltaics (ST‐OPVs) that incorporate bulk heterojunction (BHJ) active layers, a compromise is made between the visible light transmittance (VLT) and power conversion efficiency (PCE). A new strategy with a sequential‐deposition (SD) active layer involving pseudo p–i–n structures provides ST‐OPVs with simultaneously higher PCE and VLT than that of the BHJ devices at the same layer thickness.
Abstract
Semitransparent organic photovoltaics (ST‐OPVs) have great potential for use in renewable energy technologies. In bulk‐heterojunction (BHJ) ST‐OPVs, a compromise is necessary between the visible light transmittance (VLT) and the power conversion efficiency (PCE). A sequential deposition (SD) strategy that involves individually depositing a polymer donor layer (D) and a small‐molecule acceptor layer (A) as the active layer is presented; where molecular diffusion occurring at the interfacial region results in a pseudo p–i–n structure. PBDB‐T‐2F(D)/Y6(A) ST‐OPVs are fabricated with different active layer thicknesses—at 115 nm, the SD (D:A/75:40 nm) and BHJ devices (D:A/1:1.2 w) provide the champion PCE of 12.91% (VLT of 14.5%) and 12.77% (VLT of 13.4%), respectively; at 85 nm, the SD (D:A/45:40 nm) and BHJ devices (D:A/1:1.2 w) provide a PCE of 12.22% (VLT of 22.2%) and 11.23% (VLT of 16.6%), respectively. This trend indicates SD devices have larger PCE and VLT values than the BHJ devices at a given active layer thickness, and the enhancements of PCE and VLT values by the SD structures against the BHJ structures become more pronounced as the active layer thickness reduced. The SD strategy provides a new approach for achieving ST‐OPVs with both high efficiency and high transparency.
30 Jan 06:05
by Jinfeng Han,
Huidong Fan,
Qingyang Zhang,
Qin Hu,
Thomas P. Russell,
Howard E. Katz
Two n‐type polymers based on dichlorodithienylethene (ClTVT) are synthesized. Using the two polymers doped with CoCp2 and N‐DMBI, respectively, organic thermoelectric devices are prepared and compared. Doping of PClClTVT with N‐DMBI results in excellent air stability; the electrical conductivity and power factor are still maintained at 4.9 S m−1 and 9.3 µW m−1 K−2 after 222 days.
Abstract
Two donor–acceptor (D–A) polymers are obtained by coupling difluoro‐ and dichloro‐substituted forms of the electron‐deficient unit BDOPV and the relatively weak donor moiety dichlorodithienylethene (ClTVT). The conductivity and power factors of doped devices are different for the chlorinated and fluorinated BDOPV polymers. A high electron conductivity of 38.3 and 16.1 S cm−1 are obtained from the chlorinated and fluorinated polymers with N‐DMBI, respectively, and 12.4 and 2.4 S cm−1 are obtained from the chlorinated and fluorinated polymers with CoCp2, respectively, from drop‐cast devices. The corresponding power factors are 22.7, 7.6, 39.5, and 8.0 µW m−1 K−2, respectively. Doping of PClClTVT with N‐DMBI results in excellent air stability; the electron conductivity of devices with 50 mol% N‐DMBI as dopant remained up to 4.9 S m−1 after 222 days in the air, the longest for an n‐doped polymer stored in air, with a thermoelectric power factor of 9.3 µW m−1 K−2. However, the conductivity of PFClTVT‐based devices can hardly be measured after 103 days. These observations are consistent with morphologies determined by grazing incidence wide angle X‐ray scattering and atomic force microscopy.
30 Jan 06:04
by Neha Chaturvedi,
Nicola Gasparini,
Daniel Corzo,
Jules Bertrandie,
Nimer Wehbe,
Joel Troughton,
Derya Baran
Slot die coating is used to fabricate high efficiency (power conversion efficiencies (PCE) > 11.0%), stable organic solar cells based on a donor PTB7‐Th and nonfullerene acceptor IEICO‐4F. The 11% small area and 1 cm2 devices with a PCE of 9.63% show the scalability of the technique. The highest light utilization efficiency of 5.26% with a PCE of 9.07% is achieved for the all solution processed semi‐transparent solar cell.
Abstract
Slot‐die (SD) coating is used to fabricate fully solution processed organic solar cells (OSCs) based on a blend of high performance donor polymer (PTB7‐Th) and a non‐fullerene acceptor (IEICO‐4F) for stable devices over extended periods of operation. The optimization of a sequential deposition process of transport and active layers, under ambient conditions, enable high efficiency slot‐die coated solar cells with remarkable power conversion efficiencies (PCE) > 11.0% to bridge the gap between lab‐to‐fab. Fully slot‐die coated inverted OSCs are demonstrated with efficiencies reaching 11% along with 1 cm2 devices, proving the scalability and reproducibility of the proposed technique. Further, replacing the evaporated Ag electrode with solution processed Ag nanowire (AgNW) electrodes shows the highest light utilization efficiency of 5.26% for semi‐transparent OSC with a PCE of 9.07% and average visible transmission of 58%.
29 Jan 07:18
by Zhenguo Wang,
Yunfei Han,
Lingpeng Yan,
Chao Gong,
Jiachen Kang,
Hao Zhang,
Xue Sun,
Lianping Zhang,
Jian Lin,
Qun Luo,
Chang‐Qi Ma
Large‐area prepatterned silver nanowire electrodes are prepared via gravure printing, which show high uniformity and balanced conductivity (10.8 Ω sq−1) and transparency (95.4%). High power conversion efficiencies of 15.28% and 13.61% are achieved for 0.04 and 1 cm2 cells, respectively.
Abstract
With the aim of developing high‐performance flexible polymer solar cells, the preparation of flexible transparent electrodes (FTEs) via a high‐throughput gravure printing process is reported. By varying the blend ratio of the mixture solvent and the concentration of the silver nanowire (AgNW) inks, the surface tension, volatilization rate, and viscosity of the AgNW ink can be tuned to meet the requirements of gravure printing process. Following this method, uniformly printed AgNW films are prepared. Highly conductive FTEs with a sheet resistance of 10.8 Ω sq−1 and a high transparency of 95.4% (excluded substrate) are achieved, which are comparable to those of indium tin oxide electrode. In comparison with the spin‐coating process, the gravure printing process exhibits advantages of the ease of large‐area fabrication and improved uniformity, which are attributed to better ink droplet distribution over the substrate. 0.04 cm2 polymer solar cells based on gravure‐printed AgNW electrodes with PM6:Y6 as the photoactive layer show the highest power conversion efficiency (PCE) of 15.28% with an average PCE of 14.75 ± 0.35%. Owing to the good uniformity of the gravure‐printed AgNW electrode, the highest PCE of 13.61% is achieved for 1 cm2 polymer solar cells based on the gravure‐printed FTEs.
29 Jan 07:16
by Linlin Zhang,
Cuiting Kang,
Guizhi Zhang,
Zhenxiao Pan,
Zhaoshuai Huang,
Shuaihang Xu,
Huashang Rao,
Hongbin Liu,
Shengfan Wu,
Xin Wu,
Xiaosong Li,
Zonglong Zhu,
Xinhua Zhong,
Alex K.‐Y. Jen
An anion/cation synergy strategy is proposed by the incorporation of ZnI2 in CsPbI3 quantum dots (QDs) to improve the stability and photoelectric properties. The obtained Zn:CsPbI3 QDs show lower defect state density and enhanced structural stability. Perovskite quantum dot solar cells fabricated with Zn:CsPbI3 QDs exhibit a champion power conversion efficiency over 16%.
Abstract
All‐inorganic CsPbI3 quantum dots (QDs) have shown great potential in photovoltaic applications. However, their performance has been limited by defects and phase stability. Herein, an anion/cation synergy strategy to improve the structural stability of CsPbI3 QDs and reduce the pivotal iodine vacancy (V
I) defect states is proposed. The Zn‐doped CsPbI3 (Zn:CsPbI3) QDs have been successfully synthesized employing ZnI2 as the dopant to provide Zn2+ and extra I−. Theoretical calculations and experimental results demonstrate that the Zn:CsPbI3 QDs show better thermodynamic stability and higher photoluminescence quantum yield (PLQY) compared to the pristine CsPbI3 QDs. The doping of Zn in CsPbI3 QDs increases the formation energy and Goldschmidt tolerance factor, thereby improving the thermodynamic stability. The additional I− helps to reduce the V
I defects during the synthesis of CsPbI3 QDs, resulting in the higher PLQY. More importantly, the synergistic effect of Zn2+ and I− in CsPbI3 QDs can prevent the iodine loss during the fabrication of CsPbI3 QD film, inhibiting the formation of new V
I defect states in the construction of solar cells. Consequently, the anion/cation synergy strategy affords the CsPbI3 quantum dot solar cells (QDSC) a power conversion efficiency over 16%, which is among the best efficiencies for perovskite QDSCs.
29 Jan 07:10
by Ze Wang,
Qi Wei,
Xiaodong Liu,
Li Liu,
Xinyu Tang,
Jia Guo,
Shengqiang Ren,
Guichuan Xing,
Dewei Zhao,
Yonghao Zheng
Perpendicular crystal orientation and orderly n‐phase distribution in quasi‐2D perovskite films are simultaneously achieved by F‐substitution in phenethylammonium (PEA+), leading to an impressive 18.10%‐efficiency of perovskite solar cells with n = 4. Meanwhile, the horizontal crystal orientation and random n‐phase distribution are obtained in perovskite films based on PEA and (Cl/Br)‐substituted PEA, respectively.
Abstract
Halide substitution in phenethylammonium spacer cations (X‐PEA+, X = F, Cl, Br) is a facile strategy to improve the performance of PEA based perovskite solar cells (PSCs). However, the power conversion efficiency (PCE) of X‐PEA based quasi‐2D (Q‐2D) PSCs is still unsatisfactory and the underlying mechanisms are in debate. Here, the in‐depth study on the impact of halide substitution on the crystal orientation and multi‐phase distribution in PEA based perovskite films are reported. The halide substitution eliminates n = 1 2D perovskite and thus leads to the perpendicular crystal orientation. Furthermore, nucleation competition exists between small‐n and large‐n phases in PEA and X‐PEA based perovskites. This gives rise to the orderly distribution of different n‐phases in the PEA and F‐PEA based films, and random distribution in Cl‐PEA and Br‐PEA based films. As a result, (F‐PEA)2MA3Pb4I12 (MA = CH3NH3
+, n
= 4) based PSCs achieve a PCE of 18.10%, significantly higher than those of PEA (12.23%), Cl‐PEA (7.93%) and Br‐PEA (6.08%) based PSCs. Moreover, the F‐PEA based devices exhibit remarkably improved stability compared to their 3D counterparts.
29 Jan 07:10
by Bonghyun Jo,
Hansol Park,
Eswaran Kamaraj,
Sewook Lee,
Bumho Jung,
Sivaraman Somasundaram,
Gyeong G. Jeon,
Kyu‐Tae Lee,
Namdoo Kim,
Jong H. Kim,
Bong‐Gi Kim,
Tae Kyu Ahn,
Sanghyuk Park,
Hui Joon Park
The excited state characteristics of organic hole transport materials in perovskite photovoltaics (PVs), such as transition dipole moment, is confirmed to be a critical factor in improving the built‐in potential of devices for efficient charge extraction along with reduced carrier recombination. Moreover, the aggregation property of the organic semiconductor can have a synergistic effect with its excited state property for high‐efficiency perovskite PVs.
Abstract
Intrinsic characteristics of organic semiconductor‐based hole transport materials (HTMs) such as facile synthesizability, energy level tunability, and charge transport capability have been highlighted as crucial factors determining the performances of perovskite photovoltaic (PV) cells. However, their properties in the excited state have not been actively studied, although PVs are operated under solar illumination. Here, the characteristics of organic HTMs in their excited state such as transition dipole moment can be a decisive factor that can improve built‐in potential of PVs, consequently enhancing their charge extraction property as well as reducing carrier recombination. Moreover, the aggregation property of organic semiconductors, which has been an essential factor for high‐performance organic HTMs to improve their carrier transport property, can induce a synergistic effect with their excited state property for the high‐efficiency perovskite PVs. Additionally, it is also confirmed that their optical bandgaps, manipulated to have their absorption in the UV region, are beneficial to block UV light that degrades the quality of perovskite, consequently improving the stability of perovskite PV in p–i–n configuration. As a proof‐of‐concept, a model system, composed of triarylamine and imidazole‐based organic HTMs, is designed, and it is believed that this strategy paves a way toward high‐performance and stable perovskite PV devices.
29 Jan 07:10
by Fengyou Wang,
Yuhong Zhang,
Meifang Yang,
Donglai Han,
Lili Yang,
Lin Fan,
Yingrui Sui,
Yunfei Sun,
Xiaoyan Liu,
Xiangwei Meng,
Jinghai Yang
Novel interface polarization induced field‐effect passivation based on amorphous transition metal oxide is developed for efficient and ambient‐air‐stable perovskite solar cells. Comprehensive insights into the interaction between the field‐effect passivation, interface polarities, and the performance of the device have been elucidated in detail.
Abstract
Organolead halide hybrid perovskite solar cells (PSCs) have become a shining star in the renewable devices field due to the sharp growth of power conversion efficiency; however, interfacial recombination and carrier‐extraction losses at heterointerfaces between the perovskite active layer and the carrier transport layers remain the two main obstacles to further improve the power conversion efficiency. Here, novel field‐effect passivation has been successfully induced to effectively suppress the interfacial recombination and improve interfacial charge transfer by incorporating interfacial polarization via inserting a high work function interlayer between perovskite and holes transport layer. The charge dynamics within the device and the mechanism of the field‐effect passivation are elucidated in detail. The unique interfacial dipoles reinforce the built‐in field and prevent the photogenerated charges from recombining, resulting in power conversion efficiency up to 21.7% with negligible hysteresis. Furthermore, the hydrophobic interlayer also suppresses the perovskite decomposition by preventing the moisture penetration, thereby improving the humidity stability of the PSCs (>91% of the initial power conversion efficiency (PCE) after 30 d in 65 ± 5% humidity). Finally, several promising research perspectives based on field‐effect passivation are also suggested for further conversion efficiency improvements and photovoltaic applications.
29 Jan 07:07
by Kui Feng,
Ziang Wu,
Mengyao Su,
Suxiang Ma,
Yongqiang Shi,
Kun Yang,
Yang Wang,
Yujie Zhang,
Weipeng Sun,
Xing Cheng,
Limin Huang,
Jie Min,
Han Young Woo,
Xugang Guo
Highly efficient ternary all‐polymer solar cells (PSCs) based on an ultranarrow bandgap polymer acceptor are realized. The optimized ternary all‐PSCs achieve a full coverage of solar spectrum, yielding an excellent power conversion efficiency of 12.1% with a remarkable short‐circuit current density of 21.9 mA cm−2.
Abstract
Developing organic solar cells (OSCs) based on a ternary active layer is one of the most effective approaches to maximize light harvesting and improve their photovoltaic performance. However, this strategy meets very limited success in all‐polymer solar cells (all‐PSCs) due to the scarcity of narrow bandgap polymer acceptors and the challenge of morphology optimization. In fact, the power conversion efficiencies (PCEs) of ternary all‐PSCs even lag behind binary all‐PSCs. Herein, highly efficient ternary all‐PSCs are realized based on an ultranarrow bandgap (ultra‐NBG) polymer acceptor DCNBT‐TPC, a medium bandgap polymer donor PTB7‐Th, and a wide bandgap polymer donor PBDB‐T. The optimized ternary all‐PSCs yield an excellent PCE of 12.1% with a remarkable short‐circuit current density of 21.9 mA cm−2. In fact, this PCE is the highest value reported for ternary all‐PSCs and is much higher than those of the corresponding binary all‐PSCs. Moreover, the optimized ternary all‐PSCs show a photostability with ≈68% of the initial PCE retained after 400 h illumination, which is more stable than the binary all‐PSCs. This work demonstrates that the utilization of a ternary all‐polymer system based on ultra‐NBG polymer acceptor blended with compatible polymer donors is an effective strategy to advance the field of all‐PSCs.
29 Jan 07:07
by Shengyun Huang,
Yannan Liu,
Maziar Jafari,
Mohamed Siaj,
Haining Wang,
Shuyong Xiao,
Dongling Ma
The completely ITO‐free flexible organic electrochromic device shows high performance with reversible transmittance modulation in the visible region (40.2% at wavelength of 550 nm) and near‐infrared region (−68.2% at wavelength of 1600 nm). Moreover, the device presents excellent flexibility (up to 1000 bending cycles) and impressively fast switching time (5.9 s).
Abstract
Solid and flexible electrochromic (EC) devices require a delicate design of every component to meet the stringent requirements for transparency, flexibility, and deformation stability. However, the electrode technology in flexible EC devices stagnates, wherein brittle indium tin oxide (ITO) is the primary material. Meanwhile, the inflexibility of metal oxide usually used in an active layer and the leakage issue of liquid electrolyte further negatively affect EC device performance and lifetime. Herein, a novel and fully ITO‐free flexible organic EC device is developed by using Ag–Au core–shell nanowire (Ag–Au NW) networks, EC polymer and LiBF4/propylene carbonate/poly(methyl methacrylate) as electrodes, active layer, and solid electrolyte, respectively. The Ag–Au NW electrode integrated with a conjugated EC polymer together display excellent stability in harsh environments due to the tight encapsulation by the Au shell, and high area capacitance of 3.0 mF cm−2 and specific capacitance of 23.2 F g−1 at current density of 0.5 mA cm−2. The device shows high EC performance with reversible transmittance modulation in the visible region (40.2% at 550 nm) and near‐infrared region (−68.2% at 1600 nm). Moreover, the device presents excellent flexibility (>1000 bending cycles at the bending radius of 5 mm) and fast switching time (5.9 s).
29 Jan 07:00
by Jianwu Tian,
Zitong Liu,
Changchun Wu,
Wenlin Jiang,
Liangliang Chen,
Dandan Shi,
Xisha Zhang,
Guanxin Zhang,
Deqing Zhang
Conjugated D–A polymers with two types of azo groups, for which trans–cis isomerization can sequentially occur with light irradiation at different wavelengths, in the side chains possess tri‐stable semiconducting states. As a consequence, the performance of the resulting field‐effect transistors can be logically controlled by light irradiation at three different wavelengths, mimicking three‐value logic gates.
Abstract
A new design strategy for photoresponsive semiconducting polymer with tri‐stable semiconducting states is reported by simultaneous incorporation of tetra‐ortho‐methoxy‐substituted azobenzene (mAzo) and arylazopyrazole (pAzo) in the side chains. The trans‐to‐cis transformations for mAzo and pAzo groups can sequentially occur within the polymer thin film after sequential 560 and 365 nm light irradiation. Remarkably, the trans–cis isomerization of mAzo and pAzo groups can modulate the thin film crystallinity. Accordingly, the performances of the resulting field‐effect transistors (FETs) can be reversibly modulated, leading to tri‐stable semiconducting states after sequential 560, 365, and 470 nm light irradiation. Therefore, the device performance can be logically controlled by light irradiation at three different wavelengths. In addition, with light irradiation and device current as the input and output signals, the three‐value logic gate by using single FET device can be successfully mimicked.
29 Jan 06:59
by Haodong Liu,
Hongjian Zhang,
Wenqi Han,
Huijuan Lin,
Ruizi Li,
Jixin Zhu,
Wei Huang
The advances of state‐of‐the‐art 3D printed flexible strain sensors fabricated via 3D printing are summarized, focusing on different printing methods based on photocuring and materials extrusion, including Digital Light Processing, fused deposition modeling, and direct ink writing. Sensing mechanisms of 3D‐printed strain sensors are also discussed.
Abstract
The revolutionary and pioneering advancements of flexible electronics provide the boundless potential to become one of the leading trends in the exploitation of wearable devices and electronic skin. Working as substantial intermediates for the collection of external mechanical signals, flexible strain sensors that get intensive attention are regarded as indispensable components in flexible integrated electronic systems. Compared with conventional preparation methods including complicated lithography and transfer printing, 3D printing technology is utilized to manufacture various flexible strain sensors owing to the low processing cost, superior fabrication accuracy, and satisfactory production efficiency. Herein, up‐to‐date flexible strain sensors fabricated via 3D printing are highlighted, focusing on different printing methods based on photocuring and materials extrusion, including Digital Light Processing (DLP), fused deposition modeling (FDM), and direct ink writing (DIW). Sensing mechanisms of 3D printed strain sensors are also discussed. Furthermore, the existing bottlenecks and future prospects are provided for further progressing research.
28 Jan 07:48
by Ze‐Fan Yao,
Yu‐Qing Zheng,
Jin‐Hu Dou,
Yang Lu,
Yi‐Fan Ding,
Li Ding,
Jie‐Yu Wang,
Jian Pei
Conjugated polymer microwire crystals are obtained from solvated aggregates. The precise crystal packing and electronic structure in the polymer microwires are evaluated for understanding of the charge transport properties. Polymer crystal transistors of F4BDOPV‐2T exhibit higher electron mobilities of up to 5.58 cm2 V−1 s−1 with a much lower hopping energy barrier compared with conventional thin‐film transistors.
Abstract
Conjugated polymers usually form crystallized and amorphous regions in the solid state simultaneously, making it difficult to accurately determine their precise microstructures. The lack of multiscale microstructures of conjugated polymers limits the fundamental understanding of the structure–property relationships in polymer‐based optoelectronic devices. Here, crystals of two typical conjugated polymers based on four‐fluorinated benzodifurandione‐based oligo(p‐phenylene vinylene) (F4BDOPV) and naphthalenediimide (NDI) motifs, respectively, are obtained by a controlled self‐assembly process. The strong diffractivity of the polymer crystals brings an opportunity to determine the crystal structures by combining X‐ray techniques and molecular simulations. The precise polymer packing structures are useful as initial models to evaluate the charge transport properties in the ordered and disordered phases. Compared to the spin‐coated thin films, the highly oriented polymer chains in crystals endow higher mobilities with a lower hopping energy barrier. Microwire crystal transistors of F4BDOPV‐ and NDI‐based polymers exhibit high electron mobilities of up to 5.58 and 2.56 cm2 V−1 s−1, respectively, which are among the highest values in polymer crystals. This work presents a simple method to obtain polymer crystals and their precise microstructures, promoting a deep understanding of molecular packing and charge transport for conjugated polymers.
19 Jan 02:55
by Qiaoqiao Gui,
Yutong Feng,
Bingjie Chen,
Feng Gu,
Lu Chen,
Shuo Meng,
Mengzhu Xu,
Mengting Xia,
Chi Zhang,
Jinhu Yang
Unique bimetallic phosphorus trisulfide‐based hollow nanocubes made of extrinsic‐structured NiCoPS3 nanodots uniformly embedded in nitrogen‐doped graphitized carbon matrices (NiCoPS3/NC) are constructed via an elaborately designed metal–organic framework‐derived strategy, exhibiting superior lithium storage performance due to their structural/compositional advantages of high electrical conductivity, low ion diffusion barrier, improved theoretical lithium storage capacity, and relieved lithiation stress.
Abstract
The exploration of advanced electrode materials through rational structure/phase design is the key to develop high‐performance rechargeable batteries. Herein, ternary metal phosphorus trisulfides (NiCoPS3) with a bimetallic phase and an extrinsic structure of nanodots combined with nitrogen‐doped graphitized carbon (NC) are developed for lithium‐ion batteries. The designed NiCoPS3/NC holding a nanocube‐like morphology shows a set of structural/compositional advantages as lithium‐ion battery anodes including high electrical conductivity, low ion diffusion barrier, improved theoretical lithium storage capacity, and relieved lithiation stress, which are confirmed by characterizations and density functional theory calculations. As a consequence, the NiCoPS3/NC electrode displays superior comprehensive lithium storage performance, e.g., high reversible capacity (991 mAh g−1 at 0.1 A g−1), excellent cycling stability (up to 1200 cycles at 2 A g−1 and 2000 cycles at 5 A g−1 with respective capacity retention of over or nearly 100%), and good rate capability (58.4% capacity retention after a current change from 0.1 to 5 A g−1), representing the best comprehensive battery performance in MPS3‐based anodes to date.
19 Jan 02:55
by Zhongxiang Peng,
Kui Jiang,
Yunpeng Qin,
Miaomiao Li,
Nrup Balar,
Brendan T. O'Connor,
Harald Ade,
Long Ye,
Yanhou Geng
The morphological and mechanical properties of a high‐efficiency ternary organic photovoltaic blend comprising fullerene and nonfullerene acceptors are characterized in detail. The device efficiency and crack‐onset strain are maximized at the same blend composition. Furthermore, the elastic modulus of ternary blends can be captured by a theoretical model. These relations pave the way to design efficient and stretchable organic photovoltaics.
Abstract
Ternary solar cells comprising both fullerene and nonfullerene acceptors have shown a rapid increase in power conversion efficiency, which holds promise in commercial applications. Despite the rapid progress, there is still a lack of fundamental understanding of the relations between microstructure and (photovoltaic/mechanical) properties in these ternary blend systems. In this work, the dependence of molecular packing, phase separation, mechanical properties, and photovoltaic performance on acceptor composition of a recently certificated ternary system is thoroughly investigated by combined scattering and microscopy characterizations. It is demonstrated that incorporating a small amount (20% by weight) PC71BM to the PM6:N3 binary blend can afford the best device efficiency and the highest ductility simultaneously. This maximum performance is due to the optimized molecular order, orientational texture, and phase separation. Additionally, increasing the amount of PC71BM results in higher elastic modulus, as probed by two distinct methods. A more crucial observation is that the elastic modulus of ternary blends can be well captured by an extended Halpin–Tsai model. This finding is expected to enable the prediction of the elastic modulus of various kinds of ternary blends that are widely used in solar cells and other electronics.
19 Jan 02:55
by Ardalan Armin,
Wei Li,
Oskar J. Sandberg,
Zuo Xiao,
Liming Ding,
Jenny Nelson,
Dieter Neher,
Koen Vandewal,
Safa Shoaee,
Tao Wang,
Harald Ade,
Thomas Heumüller,
Christoph Brabec,
Paul Meredith
Organic photovoltaics have long promised low embodied energy, low cost solar power but have yet to make the commercial transition. Recent advances in efficiencies are potentially about to change this status‐quo, driven by a new class of semiconductors called the non‐fullerene electron acceptors. The emergence of these materials is reviewed, and perspectives provided as to future challenges and performance.
Abstract
Organic solar cells are composed of electron donating and accepting organic semiconductors. Whilst a significant palette of donors has been developed over three decades, until recently only a small number of acceptors have proven capable of delivering high power conversion efficiencies. In particular the fullerenes have dominated the landscape. In this perspective, the emergence of a family of materials–the non‐fullerene acceptors (NFAs) is described. These have delivered a discontinuous advance in cell efficiencies, with the significant milestone of 20% now in sight. Intensive international efforts in synthetic chemistry have established clear design rules for molecular engineering enabling an ever‐expanding number of high efficiency candidates. However, these materials challenge the accepted wisdom of how organic solar cells work and force new thinking in areas such as morphology, charge generation and recombination. This perspective provides a historical context for the development of NFAs, and also addresses current thinking in these areas plus considers important manufacturability criteria. There is no doubt that the NFAs have propelled organic solar cell technology to the efficiencies necessary for a viable commercial technology–but how far can they be pushed, and will they also deliver on equally important metrics such as stability?
