A novel coral-like perovskite nanostructured layer was grown on a compact perovskite foundation layer by the facile surface modification with dimethylformamide/isopropanol (DMF/IPA) as co-solvent. Surface morphological characterizations with SEM and XRD analyses revealed a growing mechanism of the new morphology, which was composed of the perovskite decomposition and recrystallization, excessive-PbI2 extraction, and sequential formation of coral-like nanostructured perovskite layer. The coral-like perovskite nanostructures resulted in significant light scattering, enhancing the light-harvesting efficiency, and thus augmenting the photocurrent density. Moreover, the geometric configuration of the perovksite solar cells was changed from planar to bulk heterojunction, which results in the acceleration of charge separation and extraction due to the high surface area at the interface between the obtained perovskite and hole-transport layers. The optimal perovskite solar cell exhibited an impressive power conversion efficiency (PCE) of 19.47%, as compared to that of the pristine cell (17.19%).
The distribution of trap states within perovskite vicinity or hetero-interfaces is the prime attribution towards carrier dynamics inferiority and low photovoltaic performances. In this work, thermally stimulated current (TSC) is performed to unravel the impact of germanium (Ge) addition in passivating and reducing trap states; consequently, to improve its carrier dynamics. The addition of 5 mol% germanium into the FA0.75MA0.25Sn1-xGexI3 (FMSGI(5)) framework strikingly suppresses the trap density from 1015–1017 cm−3 (without Ge) to 108–1014 cm−3, thereby renders longer charge diffusion length (~1 µm) and lifetime; coupled with excellent charge mobility and efficiency of 7.9%. Interestingly, the FMSGI(5) perovskite exhibits indistinguishable trap densities profile from that of MAPbI3 perovskite and exhibits a long charge diffusion length of 1 µm. Another important information to be highlighted in this paper is the advantage of SnF2 to subside the vacancy of Sn2+. This study provides deep intuitive on trap landscape, which unlocks opportunities for the designation of high performance lead-free perovskite solar cells.
Graphical abstract
The impacts of SnF2 and GeI2 additives for a new type SnGe perovskite are revealed through thermally stimulated current. The presence of both additives suppresses the Sn2+ oxidation and traps densities, additionally merits the carrier dynamics and efficiency (7.9%) of the SnGe perovskite. This work provides in-depth study on trap landscape for the designation of high performance lead-free solar cells.
Author(s): Yi Zhang, Giulia Grancini, Zhaofu Fei, Erfan Shirzadi, Xuehui Liu, Emad Oveisi, Farzaneh Fadaei Tirani, Rosario Scopelliti, Yaqing Feng, Mohammad Khaja Nazeeruddin, Paul J. Dyson
Abstract
Hybrid perovskite solar cells have attracted tremendous interest in the photovoltaic community. Despite their high defect tolerance, reducing the trap density by material engineering and surface modification is still critical to further boost performance. Here, methylammonium lead(II) iodide perovskite has been doped with imidazolium iodide in high concentrations (10–30 mol%) to boost solar cell performance, by passivating defects. Fumigation with methylamine results in the deprotonation of the embedded imidazolium cations, generating imidazole and methylammonium cations. The resulting (neutral) imidazole is extruded from the 3-D perovskite crystal and distributes around the crystal leading to auto-passivation of crystal defects. The structure of the imidazolium-PbI3 salt intermediate (i.e. formed in the absence of the methylammonium cation) has been determined and the resulting perovskite film characterized. Employed in solar cells, a power conversion efficiency (PCE) up to 20.14% is demonstrated.
Graphical abstract
A high-quality, stable perovskite film gives a power conversion efficiency of 20.14% when applied in a perovskite solar cell using imidazolium iodide (IMI) as passivator and fumigated with methylamine.
J. Mater. Chem. A, 2019, 7,3655-3663 DOI: 10.1039/C8TA11800K, Paper
Lu-Lu Jiang, Zhao-Kui Wang, Meng Li, Chun-He Li, Peng-Fei Fang, Liang-Sheng Liao A powerful sorbent of Li+, flower-like MoS2 nanocrystals, was doped into the Spiro-OMeTAD layer for highly efficient and stable perovskite solar cells. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,3737-3744 DOI: 10.1039/C8TA11293B, Paper
Tao Lei, Ruixiang Peng, Wei Song, Ling Hong, Jiaming Huang, Nannan Fei, Ziyi Ge Flexible organic solar cells (FOSCs) were fabricated based on Ag nanowire/PET films with PEDOT:PSS composite electrodes. The influence of doping PH1000 with ethylene glycol on the photovoltaic performance has also been investigated. Optimum FOSCs exhibit a PCE of 10.30%. All the FOSCs show excellent flexibility after bending and even upon total folding. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,2541-2546 DOI: 10.1039/C8TA11420J, Communication
Tainan Duan, Hua Tang, Ru-Ze Liang, Jie Lv, Zhipeng Kan, Ranbir Singh, Manish Kumar, Zeyun Xiao, Shirong Lu, Frédéric Laquai Two new small molecule donors (BDT-RO and BDT-RN) with esterified rhodanine (RE) as the terminal group are designed and synthesized. By combining with the fused-ring acceptor IDIC, a high PCE of over 9.0% is achieved by BDT-RO, and its isomer BDT-RN also shows a PCE close to 8.4%. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,2351-2359 DOI: 10.1039/C8TA10662B, Paper
Wenyan Su, Guangwei Li, Qunping Fan, Qinglian Zhu, Xia Guo, Juan Chen, Jingnan Wu, Wei Ma, Maojie Zhang, Yongfang Li A novel chlorine and alkylsilyl substituted polymer PBZ-ClSi was synthesized and the nonhalogen solvent-processed PSCs achieved an efficiency of 12.8%. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,2412-2420 DOI: 10.1039/C8TA10975C, Paper
Wei Gao, Fei Wu, Tao Liu, Guangye Zhang, Zhanxiang Chen, Cheng Zhong, Linna Zhu, Feng Liu, He Yan, Chuluo Yang Asymmetrical n-type molecules are high-performance multifunctional materials simultaneously used as ETMs or ILMs in PVKSCs and electron acceptors in OSCs. The content of this RSS Feed (c) The Royal Society of Chemistry
Energy Environ. Sci., 2019, 12,230-237 DOI: 10.1039/C8EE01831F, Paper
E. Yalcin, M. Can, C. Rodriguez-Seco, E. Aktas, R. Pudi, W. Cambarau, S. Demic, E. Palomares Herein, we studied the use of two different Self Assembled Monolayers (SAMs) made of semiconductor hole transport organic molecules to replace the most common p-type contact, PEDOT:PSS, in PiN methyl ammonium lead iodide perovskite solar cells (PSCs). The content of this RSS Feed (c) The Royal Society of Chemistry
by Yang Zhou,
Xiang Zhang,
Xubing Lu,
Xingsen Gao,
Jinwei Gao,
Lingling Shui,
Sujuan Wu,
Jun‐Ming Liu
A strategy to prepare efficient carbon‐based CsPbI2Br perovskite solar cells is explored by using Co3O4 nanomaterial as hole transport layer (HTM). It is found that the Co3O4 inorganic HTM effectively promotes photo‐generated charges separation and extraction, and suppress charge recombination at the CsPbI2Br/carbon electrode interface, leading to the enhanced performance.
Carbon‐based perovskite solar cells (PSCs) have gathered much attention due to their excellent thermal stability and low cost. However, the typically used hole‐conductor‐free PSCs based on carbon electrodes show the worst performance due to the serious charge recombination at the perovskite/carbon interface. In this work, the efficient and stable carbon‐based CsPbI2Br PSCs using Co3O4 as the hole transport material (HTM) are fabricated and their photoelectric properties are systematically investigated. It is found that the Co3O4 inorganic HTM effectively promotes photo‐generated charges separation and extraction, and suppresses charge recombination at the CsPbI2Br/carbon electrode interface, resulting in the improved photovoltaic performance. At the optimal Co3O4 concentration, the carbon‐based CsPbI2Br PSCs achieve the maximum efficiency of 11.21% with a negligible J–V hysteresis. This work provides a novel strategy to fabricate efficient and stable all‐inorganic PSCs.
by Muhammad Azam,
Kong Liu,
Shizhong Yue,
Yang Sun,
Dongyang Zhang,
Ali Hassan,
Zhijie Wang,
Huiqiong Zhou,
Shengchun Qu,
Zhanguo Wang
Precise amount of DRCN5T incorporation into perovskite precursors could effectively passivate the defect states on the surface, which results in improved the life time and mobility of carriers. An impressive PCE of 20.60% is realized with lower hysteresis and high stability under ambient conditions (RH 50–60%).
The additive engineering to hybrid organic‐inorganic perovskite precursors is an effective technique toward highly efficient stable photovoltaic devices, however, there is still a deficiency in fundamental understanding on how these additives affect the perovskite film and device performance as well. Herein is introduced a small organic molecule, DRCN5T, into a double‐cation perovskite precursor and the function on device performance is systematically investigated. An appropriate amount of DRCN5T into the precursor can promote the crystallization of film with successful suppression of δ‐FAPbI3 phase, reduce grain boundaries and adequately passivate the native defect sites. In addition, the incorporation of DRCN5T also regulates the energy level alignment of the perovskite to charge transport layer suitably. This leads to the promotion of charge transport, reduction in non‐radiative recombination, and boosts the efficiency to a value of 20.60% with greatly reduced hysteresis in the device. Moreover, the treatment by DRCN5T also significantly increases the stability of the devices in ambient environment. These findings open the gate to produce highly crystallized perovskite/organic‐molecule active layers toward commercialization of perovskite solar cells.
J. Mater. Chem. A, 2019, 7,932-939 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. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,9578-9586 DOI: 10.1039/C8TA10821H, Paper
Menglin Li, Xiuwen Xu, Yuemin Xie, Ho-Wa Li, Yuhui Ma, Yuanhang Cheng, Sai-Wing Tsang We demonstrated highly efficient and stable perovskite solar cells based on a NiOx:rGO oxide composite as the hole transport layer. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,1989-1995 DOI: 10.1039/C8TA11378E, Communication
Xinyun Dong, Pei Shi, Lulu Sun, Jing Li, Fei Qin, Sixing Xiong, Tiefeng Liu, Xueshi Jiang, Yinhua Zhou Flexible non-fullerene organic solar cells based on AgNWs embedded in polyimide substrates demonstrate a high efficiency up to 11.6%. The content of this RSS Feed (c) The Royal Society of Chemistry
The reduction and/or the fluorination of the TT‐units of the PBDTT‐TT polymers have crucial effects on the photostability of their polymer:fullerene solar cells. Reduction improves the photostability of the solar cells while fluorination destabilizes the photostability.
Polymer solar cells have a promising future for applications in our day to day usage of energy in small appliances and portable devices. However, their performance in terms of efficiency is limited by a number of factors, among which is their low open circuit voltage (Voc). It is, therefore, understandable that much effort is channeled by the scientific community in improving the Voc. One way to achieve this goal is the development of novel materials, for example, polymers, through chemical structure modification. Typical examples are addition (chlorination, fluorination, or sulfonylation) and/or reduction (from alkyl‐ester to ketone substituents) mechanisms. This paper reports on the study of the effect of these structural changes for Voc enhancement on the performance of the polymers in polymer:fullerene solar cells. In particular, it looks at seven polymers of the polybenzodithiophene‐thienothiophene family, identifying the structural changes in the thienothiophene units or their moieties as a function of Voc behavior in relation to their UV‐stability. The findings reveal that the fluorination of the TT‐units or having alkyl‐ester groups as substituents on the TT‐units is bad for photostability. However, when these alkyl‐ester groups are reduced into ketone substituents, the photostability behavior improves.
J. Mater. Chem. A, 2019, 7,3682-3690 DOI: 10.1039/C8TA11441B, Paper
Xinxin Li, Yan Wang, Qinglian Zhu, Xia Guo, Wei Ma, Xuemei Ou, Maojie Zhang, Yongfang Li All-small-molecule OSCs based on a new small molecule, P2TBR, with a non-fused ring core exhibited a record-breaking PCE of 11.5%. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,2200-2209 DOI: 10.1039/C8TA10165E, Paper
Ronglei Fan, Shaobo Cheng, Guanping Huang, Yongjie Wang, Yazhou Zhang, Srinivas Vanka, Gianluigi A. Botton, Zetian Mi, Mingrong Shen Designing a highly efficient and stable photoelectrochemical (PEC) tandem cell for unassisted solar water splitting is considered a promising approach for large-scale solar energy storage. The content of this RSS Feed (c) The Royal Society of Chemistry
J. Mater. Chem. A, 2019, 7,3612-3617 DOI: 10.1039/C8TA11515J, Paper
Chien-Yu Chen, Wei-Hung Lee, Sheng-Yi Hsiao, Wei-Lun Tsai, Lin Yang, Hong-Lin Lin, He-Jun Chou, Hao-Wu Lin The performance of vacuum-deposited organometal halide perovskite devices under low-intensity illumination was investigated. Both small- and large-area devices exhibited high power conversion efficiencies up to 30.1% and 24.9%, respectively, with excellent long-term stabilities more than one year. The content of this RSS Feed (c) The Royal Society of Chemistry
by Pandeng Li,
Mathieu Mainville,
Yuliang Zhang,
Mario Leclerc,
Baoquan Sun,
Ricardo Izquierdo,
Dongling Ma
Air‐processed and highly efficient organic solar cells based on stable phenanthridinone‐based ter‐polymer (C150H218N6O6S4)n and [6,6]‐phenyl‐C61‐butyric acid methyl ester are achieved and show superior thermal stability and photo‐stability as well as long‐term stability in ambient atmosphere. In addition, with the help of solvent additive (p‐anisaldehyde), the efficiency is improved from 6.34 to 7.41% and the related stability is further improved.
Abstract
High efficiency, excellent stability, and air processability are all important factors to consider in endeavoring to push forward the real‐world application of organic solar cells. Herein, an air‐processed inverted photovoltaic device built upon a low‐bandgap, air‐stable, phenanthridinone‐based ter‐polymer (C150H218N6O6S4)n (PDPPPTD) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) without involving any additive engineering processes yields a high efficiency of 6.34%. The PDPPPTD/PC61BM devices also exhibit superior thermal stability and photo‐stability as well as long‐term stability in ambient atmosphere without any device encapsulation, which show less performance decay as compared to most of the reported organic solar cells. In view of their great potential, solvent additive engineering via adding p‐anisaldehyde (AA) is attempted, leading to a further improved efficiency of 7.41%, one of the highest efficiencies for all air‐processed and stable organic photovoltaic devices. Moreover, the device stability under different ambient conditions is also further improved with the AA additive engineering. Various characterizations are conducted to probe the structural, morphology, and chemical information in order to correlate the structure with photovoltaic performance. This work paves a way for developing a new generation of air‐processable organic solar cells for possible commercial application.
Phonon coherences reveal the polaronic character of excitons in two-dimensional lead halide perovskites
Phonon coherences reveal the polaronic character of excitons in two-dimensional lead halide perovskites, Published online: 14 January 2019; doi:10.1038/s41563-018-0262-7
High-resolution resonant impulsive stimulated Raman spectroscopy in two-dimensional hybrid metal halide perovskites provides evidence for polaronic effects on excitons, which couple to distinct low-frequency vibrational modes of the ionic lattice.
Author(s): Yuanyuan Zhou, Hadas Sternlicht, Nitin P. Padture
Context & Scale
The recent rise of halide perovskites (HPs) has revolutionized solar cells and (opto)electronic device research. Numerous studies have implied that structural and compositional characteristics of HPs at various length scales govern the device performance, but much remains poorly understood. In this context, transmission electron microscopy (TEM) has emerged as a powerful characterization tool to accelerate our fundamental understanding of HP materials and devices, with the potential of having a significant impact on the development of HP-based solar cells and (opto)electronic devices. This perspective discusses the important unsolved materials-science problems surrounding HPs and the few available examples of TEM studies of HP materials and devices in the literature. It also highlights the urgency of application of TEM-based techniques for tackling these unsolved issues. Further research in this direction is crucial for advancing the science in the increasingly important HP materials and devices field.
Transmission electron microscopy (TEM)-based techniques are uniquely suited for site-specific structural and analytical characterization of halide perovskites (HPs) at atomic, nanometer, and micrometer length scales. TEM-based studies hold the key to understanding the nature and functionality of these fascinating materials that are at the heart of emerging solar cells and (opto)electronic devices. While TEM-based techniques have made several groundbreaking discoveries that have resulted in astonishing advancements in the field of materials science in general over the past decades, their application to HPs has been relatively sparse. Here, we provide a perspective on TEM-based studies of HPs that have been conducted so far and project a vision for how these powerful characterization techniques can be brought to bear on research problems in the field of HPs. An outlook discussing important challenges and opportunities that lay ahead is also presented.
by Yi Hou,
Chen Xie,
Vuk V. Radmilovic,
Bianka Puscher,
Mingjian Wu,
Thomas Heumüller,
André Karl,
Ning Li,
Xiaofeng Tang,
Wei Meng,
Shi Chen,
Andres Osvet,
Dirk Guldi,
Erdmann Spiecker,
Velimir R. Radmilović,
Christoph J. Brabec
Mesoscale‐structured materials offer broad applications owing to their high surface areas and tunable surface energy. A novel route to fabricate organic‐based mesoscale‐structured interfaces for perovskite solar cells using a roll‐to‐roll compatible process is presented. The efficient infiltration of organic porous structures based on assembled crystalline nanoparticles allows engineering perovskite solar cells with excellent efficiency, stability, and lateral homogeneity.
Abstract
Mesoscale‐structured materials offer broad opportunities in extremely diverse applications owing to their high surface areas, tunable surface energy, and large pore volume. These benefits may improve the performance of materials in terms of carrier density, charge transport, and stability. Although metal oxides–based mesoscale‐structured materials, such as TiO2, predominantly hold the record efficiency in perovskite solar cells, high temperatures (above 400 °C) and limited materials choices still challenge the community. A novel route to fabricate organic‐based mesoscale‐structured interfaces (OMI) for perovskite solar cells using a low‐temperature and green solvent–based process is presented here. The efficient infiltration of organic porous structures based on crystalline nanoparticles allows engineering efficient “n‐i‐p” and “p‐i‐n” perovskite solar cells with enhanced thermal stability, good performance, and excellent lateral homogeneity. The results show that this method is universal for multiple organic electronic materials, which opens the door to transform a wide variety of organic‐based semiconductors into scalable n‐ or p‐type porous interfaces for diverse advanced applications.
J. Mater. Chem. A, 2019, 7,2283-2290 DOI: 10.1039/C8TA10827G, Paper
Thomas J. Routledge, Michael Wong-Stringer, Onkar S. Game, Joel A. Smith, James E. Bishop, Naoum Vaenas, Benjamin G. Freestone, David M. Coles, Trevor McArdle, Alastair R. Buckley, David G. Lidzey Perovskite solar cells utilising NiO and TiO2 charge-extraction layers, deposited via high-speed, low substrate-temperature reactive electron-beam evaporation, achieve 15.8% PCE. The content of this RSS Feed (c) The Royal Society of Chemistry
by Hongjiang Li,
Xiaodong Li,
Weiyan Wang,
Jinhua Huang,
Jia Li,
Yuehui Lu,
Junwei Chang,
Junfeng Fang,
Weijie Song
Foldable paper‐based perovskite solar cells (PSCs) with high power conversion efficiency of 13.19% and robust foldability are demonstrated. Beneficial from ultrathin cellophane substrates combined with foldable TiO2/ultrathin Ag/TiO2 electrodes, the solar cells exhibit 50 single folding stability at full angle range from −180° to 180° and 10 dual folding stability, enabling size compactness and shape transformation of paper‐based PSCs.
Foldable paper‐based solar cells are attractive power sources for wearable and portable applications. Currently, low power conversion efficiency (PCE) and degradation under different folding conditions restrict practical applications of paper‐based solar cells. Herein are constructed solar cells on cellophane paper using oxide/ultrathin Ag/oxide (OMO) and perovskite as electrodes and absorbers, respectively. The perovskite solar cell (PSC) on cellophane exhibits a PCE of 13.19%, the highest among all the paper‐based solar cells. More importantly, beneficial from ultrathin cellophane substrates combined with foldable OMO electrodes, PSCs on paper exhibit 50 single folding and 10 dual folding stability: they preserve 85.3 and 84.1% of the initial PCE after −180° and +180° single folding for 50 cycles, respectively; and they remain 67.2 and 55.3% of the initial PCE after 10 inner and outer dual folding cycles, respectively. Furthermore, the solar cells after dual folding show serious cracks and delamination, leading to faster degradation than single folding. The highly efficient, foldable, and lightweight PSCs on cellophane are promising for future self‐powered paper‐based electronic applications.
