by Claudia Caddeo,
Daniela Marongiu,
Simone Meloni,
Alessio Filippetti,
Francesco Quochi,
Michele Saba,
Alessandro Mattoni
Model potential molecular dynamics explains the large water contact angle observed on hydrophilic methylammonium lead iodide. Liquid water degrades the methylammonium lead iodide surface with the formation of superficial hydrophobic lead iodide layers already in the first milliseconds after contact. Present study paves the way to the characterization of degrading perovskites by water contact angle measurements.
Abstract
Surface properties are often assessed with measurements of the contact angle of a water drop. The process is however flawed for the very important class of hybrid perovskite materials, extensively employed in solar cells and optoelectronics research, because they are water soluble and their surface degrades during contact angle measurements. While hybrid perovskites are considered to be highly hydrophilic, a contact angle with water of 83° can be measured, as if they were almost hydrophobic. By combining experiments and simulations, the actual value is explained as the result of the interaction of water with degraded superficial layers that form over sub‐millisecond time scale at the water/perovskite interface. The models are validated against contact angle measurements for water on a variety of substrates, and are referenced to with the Young–Dupré relation between liquid–solid adhesion and contact angle. Present work reconciles the hydrophilic nature of methylammonium lead iodide with the apparent hydrophobic behavior in contact angle measurements, proposing a methodology for the study of contact angle on evolving substrates.
J. Mater. Chem. A, 2018, Accepted Manuscript DOI: 10.1039/C8TA10510C, Paper
XIAOMING ZHAO, Lixian Tian, Tianjun Liu, Hongli Liu, Shirong Wang, Xianggao Li, Oliver Fenwick, Sheng-Bin Lei, Wenping Hu Organic-inorganic hybrid perovskite solar cells (PSCs) employing a mesoporous metal-oxide scaffold are now at the forefront of solution-processing photovoltaic cells, yielding a power conversion efficiency exceeding 23%. However, processing temperatures... The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. C, 2018, Accepted Manuscript DOI: 10.1039/C8TC05475D, Paper
Chuanfei Wang, Shaofei Ni, Slawomir Braun, Mats Fahlman, Xianjie Liu Due to the rapid development of non-fullerene acceptors (NFAs), the efficiency of organic solar cells steadily is being improved. The stability of organic solar cells also is expected to be... The content of this RSS Feed (c) The Royal Society of Chemistry
by Haowei Huang, Haifeng Yuan, Jiwu Zhao, Guillermo Solís-Fernández, Chen Zhou, Jin Won Seo, Jelle Hendrix, Elke Debroye, Julian A. Steele, Johan Hofkens, Jinlin Long, Maarten B. J. Roeffaers
J. Mater. Chem. A, 2019, 7,64-96 DOI: 10.1039/C8TA09383K, Review Article
Yanfang Geng, Ailing Tang, Keisuke Tajima, Qingdao Zeng, Erjun Zhou Dithieno[3,2-b:2′,3′-d]pyrrole (DTP) and its derivatives have occupied an important position in both electron-rich and electron-deficient building blocks to construct photovoltaic materials. Here, we highlight the exciting progress of donors based on original DTP, N-acyl DTP and fused DTP and acceptors based on lactam and imide, respectively. The content of this RSS Feed (c) The Royal Society of Chemistry
Edge‐functionalized graphene nanoplatelets (EFGnPs), as counter electrode (CE) materials, have demonstrated an excellent performance for dye‐sensitized solar cells (DSSCs). Specific edge groups can provide electrocatalytic active sites for iodine and cobalt reduction reactions. Given the promising potential in metal‐free CEs, research directions are suggested to discover more efficient functional groups and to realize metal‐free‐carbon‐based DSSCs.
Abstract
A scalable and low‐cost production of graphene nanoplatelets (GnPs) is one of the most important challenges for their commercialization. A simple mechanochemical reaction has been developed and applied to prepare various edge‐functionalized GnPs (EFGnPs). EFGnPs can be produced in a simple and ecofriendly manner by ball milling of graphite with target substances (X = nonmetals, halogens, semimetals, or metalloids). The unique feature of this method is its use of kinetic energy, which can generate active carbon species by unzipping of graphitic CC bonds in dry conditions (no solvent). The active carbon species efficiently pick up X substance(s), leading to the formation of graphitic CX bonds along the broken edges and the delamination of graphitic layers into EFGnPs. Unlike graphene oxide (GO) and reduced GO (rGO), the preparation of EFGnPs does not involve toxic chemicals, such as corrosive acids and toxic reducing agents. Furthermore, the prepared EFGnPs preserve high crystallinity in the basal area due to their edge‐selective functionalization. Considering the available edge X groups that can be selectively employed, the potential applications of EFGnPs are unlimited. In this context, the synthesis, characterizations, and applications of EFGnPs, specifically, as metal‐free carbon‐based electrocatalysts for dye‐sensitized solar cells (DSSCs) in both cobalt and iodine electrolytes are reviewed.
Addressing the stability issue of perovskite solar cells for commercial applications
Addressing the stability issue of perovskite solar cells for commercial applications, Published online: 10 December 2018; doi:10.1038/s41467-018-07255-1
When translating photovoltaic technology from laboratory to commercial products, low cost, high power conversion efficiency, and high stability (long lifetime) are the three key metrics to consider in addition to other factors, such as low toxicity, low energy payback time, etc. As one of the most promising photovoltaic materials with high efficiency, today organic–inorganic metal halide perovskites draw tremendous attention from fundamental research, but their practical relevance still remains unclear owing to the notorious short device operation time. In this comment, we discuss the stability issue of perovskite photovoltaics and call for standardized protocols for device characterizations that could possibly match the silicon industrial standards.
by Xiuling Li,
Zhufeng Hou,
Shoushuai Gao,
Yu Zeng,
Jianping Ao,
Zhiqiang Zhou,
Bo Da,
Wei Liu,
Yun Sun,
Yi Zhang
In article no. 1800198, Bo Da, Yi Zhang, and co‐workers determine the optimal doping content of Mn2+ in CZTSSe films effectively and rapidly to achieve the best solar cell efficiency by machine learning. A CM0.05Z0.95TSSe solar cell with an efficiency of 8.93% is achieved.
In article no. 1800177, Zhi Yang, Minqiang Wang, and Jinjuan Dou discuss interface engineering in n‐i‐p metal halide perovskite solar cells, achieved by introducing 2D perovskites, functional molecules, quantum dots, and an insulating layer, which allows for better energy‐level alignment, passivating traps, resisting moisture, and suppressing ion migration. This contributes to improved performance, enhanced long‐term stability, and eliminated photocurrent hysteresis.
by Ming Wang,
Peng Zeng,
Sai Bai,
Jinwen Gu,
Faming Li,
Zhou Yang,
Mingzhen Liu
In article no. 1800217, Mingzhen Liu and co‐workers fabricate a Cs2Ag‐BiBr6 double perovskite film that is potentially desirable for lead‐free solar cell applications. The films exhibit high quality in terms of large compact grains, high uniformity, and long‐term stability.
by Christopher B. Cooper,
Edward J. Beard,
Álvaro Vázquez‐Mayagoitia,
Liliana Stan,
Gavin B. G. Stenning,
Daniel W. Nye,
Julian A. Vigil,
Tina Tomar,
Jingwen Jia,
Govardhana B. Bodedla,
Song Chen,
Lucía Gallego,
Santiago Franco,
Antonio Carella,
K. R. Justin Thomas,
Song Xue,
Xunjin Zhu,
Jacqueline M. Cole
A design‐to‐device study, based on algorithmic encodings of structure–property relationships, is used to identify new materials with panchromatic optical absorption. 9431 dyes are mined from the literature and optimally paired together to afford co‐sensitizing dyes with complementary optical absorption properties. Promising combinations are experimentally verified in dye‐sensitized solar cells and novel methods for characterizing dye aggregation in co‐sensitized devices are presented.
Abstract
Data‐driven materials discovery has become increasingly important in identifying materials that exhibit specific, desirable properties from a vast chemical search space. Synergic prediction and experimental validation are needed to accelerate scientific advances related to critical societal applications. A design‐to‐device study that uses high‐throughput screens with algorithmic encodings of structure–property relationships is reported to identify new materials with panchromatic optical absorption, whose photovoltaic device applications are then experimentally verified. The data‐mining methods source 9431 dye candidates, which are auto‐generated from the literature using a custom text‐mining tool. These candidates are sifted via a data‐mining workflow that is tailored to identify optimal combinations of organic dyes that have complementary optical absorption properties such that they can harvest all available sunlight when acting as co‐sensitizers for dye‐sensitized solar cells (DSSCs). Six promising dye combinations are shortlisted for device testing, whereupon one dye combination yields co‐sensitized DSSCs with power conversion efficiencies comparable to those of the high‐performance, organometallic dye, N719. These results demonstrate how data‐driven molecular engineering can accelerate materials discovery for panchromatic photovoltaic or other applications.
Di Yang, Muhan Cao, Qixuan Zhong, Pengli Li, Xiaohong Zhang, Qiao Zhang Recently, all-inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals (NCs) have attracted much attention because of their excellent photophysical properties and promising applications in diverse fields.... The content of this RSS Feed (c) The Royal Society of Chemistry
Energy Environ. Sci., 2019, 12,384-395 DOI: 10.1039/C8EE02560F, Paper
Rui Sun, Jing Guo, Chenkai Sun, Tao Wang, Zhenghui Luo, Zhuohan Zhang, Xuechen Jiao, Weihua Tang, Chuluo Yang, Yongfang Li, Jie Min A universal layer-by-layer solution-processing approach is proven to be effective for the fabrication of high-performance non-fullerene organic solar cells. The content of this RSS Feed (c) The Royal Society of Chemistry
Fluorination of molecular donors and acceptors enables an effective tuning of the energetics in organic bulk heterojunctions, leading to enhanced power conversion efficiencies in organic solar cells with non-fullerene acceptors. To date, the impacts of fluorination on the dielectric properties and the key processes of charge dissociation and recombination are still poorly understood. Based on the fluorinated PBDBT-2F donor and IT-4F acceptor with a favorably enhanced dielectric constant in the blend films, we explore key factors attributing to the realized high fill factor (0.745) and efficiency (13.4%) in the solar cells. Through comparing the IT-4F solar cell to that with non-fluorinated ITIC acceptor, we identify distinct recombination profiles in the IT-4F based device that exhibits a highly efficient charge dissociation together with a small reduction factor (3.71 ×10−2) for bi-molecular recombination and a low recombination coefficient of 2.404 × 10–13 cm−3 s−1. These particularities lead to an ultrafast carrier sweepout < 30 ns with mitigated recombination losses in the device with fluorinated acceptor. The modulated photophysical processes are correlated to the increased dielectric constant in the blend film, with which charge transfer exciton binding energies are likely to be reduced. This work enriches our fundamental insights into molecular engineering with fluorination toward high performance non-fullerene organic solar cells.
Graphical abstract
Based on polymer solar cells comprising of the PBDBT-2F donor blended with a fluorinated IT-4F and representative ITIC acceptors, we investigate the dielectric properties and key photophysical processes attributing to the impressive fill factor (~0.75) and power conversion efficiency (~13.4%). We identify synergetic effects of improved charge separation, reduced bimolecular recombination couple with a very rapid carrier sweepout in the solar cells with IT-4F, which can be linked to the enlarged dielectric constant in the blend film due to stronger intermolecular interactions.
J. Mater. Chem. A, 2019, 7,353-362 DOI: 10.1039/C8TA10094B, Paper
Tie Liu, Pengyu Su, Li Liu, Jun Wang, Shuang Feng, Jiejing Zhang, Ri Xu, Haibin Yang, Wuyou Fu The surface morphology and J–V curves of CH3NH3PbI3 films with and without IPA/[I3−] treatment. The content of this RSS Feed (c) The Royal Society of Chemistry
Energy Environ. Sci., 2019, 12,865-886 DOI: 10.1039/C8EE02852D, Review Article
Qiong Wang, Nga Phung, Diego Di Girolamo, Paola Vivo, Antonio Abate All inorganic perovskite solar cells lead to extended device lifespan in an accelerated ageing test. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. C, 2019, 7,111-118 DOI: 10.1039/C8TC05035J, Paper
Mai Ha Hoang, Gi Eun Park, Suna Choi, Chang Geun Park, Su Hong Park, Tuyen Van Nguyen, Sangjun Kim, Kyungwon Kwak, Min Ju Cho, Dong Hoon Choi A series of conjugated terpolymers bearing weak and strong accepting units were synthesized. Their optical and electrochemical properties and device performance can be easily tuned by controlling molar ratio of two accepting units. The content of this RSS Feed (c) The Royal Society of Chemistry
by Zhifa Liu, Lisa Krückemeier, Benedikt Krogmeier, Benjamin Klingebiel, José A. Márquez, Sergiu Levcenko, Senol Öz, Sanjay Mathur, Uwe Rau, Thomas Unold, Thomas Kirchartz
Organic photovoltaics (OPVs) have attracted considerable attention in the last decade due to some potential advantages, such as flexibility, light weight, possible semi-transparency, and fast large-area fabrication with low energy consumption. To achieve higher performing OPVs, a tandem structure was invented by stacking two or more sub-cells together. In tandem OPVs, the photon utilization efficiency can be improved and the thermal losses can be reduced. Herein, a simple strategy to balance the voltage-current trade-off in tandem OPVs by employing mixed non-fullerene acceptors in rear sub-cells is reported. By this strategy, tandem OPVs exhibited the best power conversion efficiency (PCE) of 13.3% in the lab. Importantly, the tandem devices were certified by the National Renewable Energy Laboratory (NREL) under the new protocols (asymptotic scans), and a PCE of 11.52% was achieved and recognized on the most recent NREL chart.
Summary
A tandem structure was invented to enhance photon utilization efficiency and reduce thermal loss. Considering the unique advantages of non-fullerene acceptors (NFAs), the combination of NFAs and the tandem concept shows great potential for organic photovoltaics (OPVs). Herein, a simple strategy to balance the voltage-current trade-off in tandem OPVs by employing mixed NFAs in rear sub-cells is reported. The VOC and JSC of rear sub-cells can be tuned by using the blend of donor/NFA/NFA. This strategy offers an easy approach to balance the VOC and JSC in tandem OPVs toward higher power conversion efficiency (PCE) without rational and careful synthesis of new materials. Tandem OPVs based on mixed NFAs in rear sub-cells exhibited the best PCE of 13.3% in the lab. Importantly, the tandem devices were certified by the National Renewable Energy Laboratory (NREL) under asymptotic scans, and a PCE of 11.52% was achieved and recognized on the most recent NREL chart.
J. Mater. Chem. A, 2018, Advance Article DOI: 10.1039/C8TA09806A, Communication
Wu-Qiang Wu, Lianzhou Wang A novel 3D optoelectronic electrode consisting of antireflective TiO2 nanowires and compact CH3NH3PbI3 microcuboids is designed for efficient perovskite photovoltaics. To cite this article before page numbers are assigned, use the DOI form of citation above. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. C, 2018, Accepted Manuscript DOI: 10.1039/C8TC04746D, Paper
Xiao'e Jia, Zhiming Chen, Chunhui Duan, Zhenfeng Wang, Qingwu Yin, Fei Huang, Yong Cao In this work we report three novel polythiophene derivatives (P4T2F-HD, P4T2F-HD/BO, and P4T2F-BO) which are synthesized via a three-step reaction for each case. The polymers show excellent coplanarity and desired... The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2018, Accepted Manuscript DOI: 10.1039/C8TA09452G, Review Article
Jin Hyuck Heo, David S. Lee, Dong Hee Shin, Sang Hyuk Im Perovskite solar cells (PSCs) have attracted a great deal of attention due to their combined advantages of high efficiency and good flexibility. Here, we addressed the latest technology and future... The content of this RSS Feed (c) The Royal Society of Chemistry
by Xiaoqing Jiang,
Dongping Wang,
Ze Yu,
Wanying Ma,
Hai‐Bei Li,
Xichuan Yang,
Feng Liu,
Anders Hagfeldt,
Licheng Sun
Two new copper (II) phthalocyanine (CuPc) derivatives, namely CuPc‐Bu and CuPc‐OBu, are designed by molecular engineering of the non‐peripheral substituents of the Pc rings, and are further explored as dopant‐free hole‐transporting materials (HTMs) in perovskite solar cells (PSCs). The PSCs based on pristine CuPc‐OBu as HTMs afford a maximum power conversion efficiency of 17.6%, which is considerably higher than that of the devices with CuPc‐Bu (14.3%).
Abstract
Copper (II) phthalocyanines (CuPcs) have attracted growing interest as promising hole‐transporting materials (HTMs) in perovskite solar cells (PSCs) due to their low‐cost and excellent stability. However, the most efficient PSCs using CuPc‐based HTMs reported thus far still rely on hygroscopic p‐type dopants, which notoriously deteriorate device stability. Herein, two new CuPc derivatives are designed, namely CuPc‐Bu and CuPc‐OBu, by molecular engineering of the non‐peripheral substituents of the Pc rings, and applied as dopant‐free HTMs in PSCs. Remarkably, a small structural change from butyl groups to butoxy groups in the substituents of the Pc rings significantly influences the molecular ordering and effectively improves the hole mobility and solar cell performance. As a consequence, PSCs based on dopant‐free CuPc‐OBu as HTMs deliver an impressive power conversion efficiency (PCE) of up to 17.6% under one sun illumination, which is considerably higher than that of devices with CuPc‐Bu (14.3%). Moreover, PSCs containing dopant‐free CuPc‐OBu HTMs show a markedly improved ambient stability when stored without encapsulation under ambient conditions with a relative humidity of 85% compared to devices containing doped Spiro‐OMeTAD. This work thus provides a fundamental strategy for the future design of cost‐effective and stable HTMs for PSCs and other optoelectronic devices.
by Changyeon Lee,
Hae Rang Lee,
Joonhyeong Choi,
Youngkwon Kim,
Thanh Luan Nguyen,
Wonho Lee,
Bhoj Gautam,
Xiang Liu,
Kai Zhang,
Fei Huang,
Joon Hak Oh,
Han Young Woo,
Bumjoon J. Kim
In article number 1802674, Han Young Woo, Bumjoon J. Kim and co‐workers report a water‐ethanol process for eco‐friendly fabrication of polymer electronic devices. The authors discover that water‐ethanol co‐solvents remarkably improve the solubility of the oligoethylene glycol side chain‐based electroactive materials, as compared to ethanol or water itself. This new process enables the fabrication of efficient and air‐stable organic field‐effect transistors and polymer solar cells.
In article number 1802323, Chih‐Ping Chen and co‐workers demonstrate hydrophilic carbon nanodots efficient additives in perovskite solar cells (PSC). The p‐i‐n PSC device incorporating these additives demonstrated a power conversion efficiency of 20.2% and exhibited excellent air‐stability, maintaining high PCEs (25 °C and a humidity of 40%) for over 500 h.
