Recent progress in efficient hybrid lead halide perovskite solar cells

The efficiency of perovskite solar cells (PSCs) has been improved from 9.7 to 19.3%, with the highest value of 20.1% achieved in 2014. Such a high photovoltaic performance can be attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths of the hybrid lead halide perovskite materials. In this review, some fundamental details of hybrid lead iodide perovskite materials, various fabrication techniques and device structures are described, aiming for a better understanding of these materials and thus highly efficient PSC devices. In addition, some advantages and open issues are discussed here to outline the prospects and challenges of using perovskites in commercial photovoltaic devices.     

Recent progress in efficient hybrid lead halide perovskite solar cells

Abstract

The efficiency of perovskite solar cells (PSCs) has been improved from 9.7 to 19.3%, with the highest value of 20.1% achieved in 2014. Such a high photovoltaic performance can be attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths of the hybrid lead halide perovskite materials. In this review, some fundamental details of hybrid lead iodide perovskite materials, various fabrication techniques and device structures are described, aiming for a better understanding of these materials and thus highly efficient PSC devices. In addition, some advantages and open issues are discussed here to outline the prospects and challenges of using perovskites in commercial photovoltaic devices.     

基于有机金属卤化物钙钛矿材料的全固态太阳能电池研究进展

作为太阳能电池的光吸收剂,有机金属卤化物钙钛矿材料不仅具有高效的光吸收能力和载流子迁移率,还具有独特的双极性特征,能同时传输电子和空穴,使其成为优异的光伏材料,掀起了基于钙钛矿材料太阳能电池的研究热潮。介绍了近几年来基于有机金属卤化物钙钛矿材料的全固态太阳能电池的发展情况,总结了有机金属卤化物钙钛矿材料的结构和特性,对目前几类典型的钙钛矿太阳能电池进行了讨论,并展望了全固态钙钛矿太阳能电池的产业化应用前景。     

倒置钙钛矿太阳能电池的空穴传输层的研究进展

倒置钙钛矿太阳能电池(PSCs)具有器件结构简单、吸光系数高、迟滞效应小、良好的缺陷容忍性等优点,受到了广泛的关注。但倒置器件光电转换效率(PCE)尚有待提高,究其原因是空穴传输层(HTL)和钙钛矿层界面处的能量损失表现出相对较小的开路电压。文章综述了包括有机聚合物、无机物、尖晶石氧化物等作为空穴传输材料的相关研究进展,进一步分析了通过调节电极/空穴传输层能级使之与钙钛矿价带匹配,及通过界面修饰促进器件对载流子的注入与收集,从而提高光电转换效率的研究现状。对提高倒置钙钛矿太阳能电池性能的研究具有一定的指导意义,最后对倒置器件的应用前景进行了展望。     

New trends for solar cell development and recent progress of dye sensitized solar cells

This article reviews the new concepts and new trends of solar cell development. To increase the photoelectric conversion efficiency, reduce the cost, and for application in a much broader field, thin film solar cell, flexible solar cell, and tandem solar cell have become important subjects to be studied. As the representative of the solar cells of the third generation, the progress and challenges of dye sensitized solar cell was also reviewed.     

Tailoring interface of lead-halide perovskite solar cells

Lead-halide perovskite solar cells (PSCs) have attracted tremendous attention during the past few years owing to their extraordinary electronic and photonic properties.To improve the performances of PSCs,many researchers have focused on the compositional engineering,solvent engineering,and film fabrication methodologies.Interfacial engineering of PSCs has become a burgeoning field in which researchers aim to deeply understand the mechanisms of cells and thereby increase the efficiency and stability of PSCs.This review focuses on the interface tailoring of lead-halide PSCs,including the modification of each layer of the cell structure (i.e.,perovskite absorber,electron-transport layers,and holetransport layers) and the interfacial materials that can be introduced into the PSCs.     

Moisture-driven phase transition for improved perovskite solar cells with reduced trap-state density

We report a mechanistic understanding of a moisture-driven intermediate-phase transition that improves the quality of perovskite thin films based on a lead-acetate precursor,improving the power-conversion efficiency.We clarify the composition of the intermediate phase and attribute the transition of this phase to the hygroscopic nature of the organic product,i.e.,methylammonium acetate.Thermal annealing aids in the coarsening of the grains.These decoupled processes result in better crystal formation with a lower spatial and energetic distribution of traps.Thermal annealing of the films without exposure to air results in a faster intermediate-phase transition and grain coarsening,which occur simultaneously,leading to disorder in the films and a higher deep trap-state density.Our results indicate the need for a humid environment for the growth of high-quality perovskite films and provide insight into intermediate-phase dissociation and conversion kinetics.Thus,they are useful for the large-scale production of efficient solution-processed perovskite solar cells.     

Low-temperature processed solar cells with formamidinium tin halide perovskite/fullerene heterojunctions

A new type of lead-free, formamidinium (FA)-based halide perovskites, FASnI₂Br, are investigated as light-harvesting materials for low-temperature processed p–i–n heterojunction solar cells with different configurations. The FASnI₂Br perovskite, with a band-gap of 1.68 eV, exhibits optimal photovoltaic performance after low-temperature annealing at 75 °C. By using C₆₀ as electron-transport layer, the device yields a hysteresis-less power conversion efficiency of 1.72%. The possible use of an inorganic MoO _x film as a new type of independent hole-transport layer for the present tin-based perovskite solar cells is also demonstrated.

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宽波段减反膜实现23.9%效率的平面异质结构钙钛矿太阳能电池

虽然钙钛矿太阳能电池效率的发展令人鼓舞,但是由于光反射造成的器件基底界面的光子损失等问题仍然没有解决.光管理是降低反射损失并提高器件效率的有效途径.因此,我们设计了双层减反膜以涂敷在(FAPbI₃)_x(MAPbBr₃)_1-x钙钛矿太阳能电池的玻璃基底外侧,以期达到增加光吸收和提高器件效率的目的.该研究中的减反膜底层由硅聚合物构成,上层由氟代硅聚合物和六甲基二硅氧烷/介孔二氧化硅纳米粒子复合而成.通过精确调控上下层的折射率及厚度,我们在宽波段范围内实现了玻璃基底透过率从最高约90%显著提升到95%.在电池器件的玻璃基底外侧溶液涂膜制备减反膜后,(FAPbI₃)_x(MAPbBr₃)_1-x钙钛矿太阳能电池在保持填充因子和开路电压不变的情况下,短路电流和效率分别从25.5 mA cm^-2和22.7%提高到26.5 mA cm^-2和23.9%.本研究提出了一种简单、高效的通过双层减反膜的光管理提高太阳能电池效率的方法,且此方法可拓展到其他类型太阳能电池体系.     

TiO2纳米碗阵列作为电子传输层构筑高效率彩色钙钛矿太阳能电池（英文）

钙钛矿太阳能电池的飞速发展及其在构筑一体化和可穿戴器件中的应用前景激发了人们对于彩色钙钛矿太阳能电池的浓厚兴趣,但如何将可见光宽波段吸收且具有高吸光系数的钙钛矿材料构筑成高性能的彩色太阳能电池仍是一个挑战.本文利用TiO2纳米碗阵列作为结构化的电子传输层,并在纳米碗内均匀填充一层CH3NH3PbI3钙钛矿薄膜,成功制备了具有鲜艳结构色的钙钛矿@TiO2纳米碗阵列薄膜,其结构色具有显著的角度依赖特征.通过路易斯酸碱加合物法制备得到基于醋酸铅的新型晶态中间体薄膜,使得高质量的CH3NH3PbI3钙钛矿薄膜能够在纳米碗内均匀填充.利用该钙钛矿@TiO2纳米碗薄膜可以制备出具有鲜艳结构色的平面异质结钙钛矿太阳能电池,其最高光电转化效率可以达到16.94%,平均效率达到15.47%,均高于现已报道的彩色钙钛矿太阳能电池的转化效率.     

碳材料在钙钛矿太阳能电池中的应用

钙钛矿太阳能电池具有材料成本低廉、生产工艺简单、光电转换效率高等优点,发展前景十分光明。碳材料因其价格低廉、高导电性、疏水性和化学稳定性等特点,被应用在钙钛矿太阳能电池的各个组成部分,用于提高电池性能和降低成本。本文根据应用在钙钛矿太阳能电池中的碳材料的维数进行分类,分别介绍了零维的C60、碳量子点和石墨烯量子点,一维的碳纳米管,二维的石墨烯及其衍生物、石墨炔和三维的石墨等在钙钛矿太阳能电池中的应用,对于将来实现钙钛矿太阳能电池的低成本商业化和大规模制造具有重要意义。     

Increasing open circuit voltage by adjusting work function of hole-transporting materials in perovskite solar cells

A series of conductive polymers, i.e., poly(3-methylthiophene) (PMT), poly(thiophene) (PT), poly(3-bromothiophene) (PBT) and poly(3-chlorothiophene) (PCT), were prepared via the electrochemical polymerization process. Subsequently, their application as hole-transporting materials (HTMs) in CH₃NH₃PbI₃ perovskite solar cells was explored. It was found that rationally increasing the work function of HTMs proves beneficial in improving the open circuit voltage (V _oc) of the devices with an ITO/conductive-polymer/CH₃NH₃PbI₃/C₆₀/BCP/Ag structure. In addition, the higher-V _oc devices with a higher-work-function HTM exhibited higher recombination resistances. The highest open circuit voltage of 1.04 V was obtained from devices with PCT, with a work function of–5.4 eV, as the hole-transporting layer. Its power conversion efficiency attained a value of approximately 16.5%, with a high fill factor of 0.764, an appreciable open voltage of 1.01 V and a short circuit current density of 21.4 mA·cm^–2. This simple, controllable and low-cost manner of preparing HTMs will be beneficial to the production of large-area perovskite solar cells with a hole-transporting layer.

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基于能带工程制备氧化镍基底的高效锡-铅共混钙钛矿太阳能电池

钙钛矿叠层太阳能电池因为具有超过肖克利-奎伊瑟效率极限的潜力而备受关注.窄带隙锡-铅(Sn-Pb)共混钙钛矿太阳能电池(PSCs)在钙钛矿叠层太阳能电池的构建中起着关键作用.制备稳定性好、可低温处理的空穴输送层是构建高效Sn-Pb钙钛矿太阳能电池和钙钛矿叠层太阳能电池的关键.在此,我们开发了一种室温处理的纳米晶体氧化镍...     

Optical management for efficiency enhancement in hybrid organic-inorganic lead halide perovskite solar cells

In a few years only, solar cells using hybrid organic–inorganic lead halide perovskites as optical absorber have reached record photovoltaic energy conversion efficiencies above 20%. To reach and overcome such values, it is required to tailor both the electrical and optical properties of the device. For a given efficient device, optical optimization overtakes electrical one. Here, we provide a synthetic review of recent works reporting or proposing so-called optical management approaches for improving the efficiency of perovskite solar cells, including the use of anti-reflection coatings at the front substrate surface, the design of optical cavities integrated within the device, the incorporation of plasmonic or dielectric nanostructures into the different layers of the device and the structuration of its internal interfaces. We finally give as outlooks some insights into the less-explored management of the perovskite fluorescence and its potential for enhancing the cell efficiency.     

2D-Antimonene-assisted hetero-epitaxial growth of perovskite films for efficient solar cells

There are many grain boundaries and defects in polycrystalline perovskite films, resulting in sacrificed efficiency and instability for perovskite solar cells (PSCs). By regulating the growth of perovskite grains along the vertical direction through epitaxial growth, one may expect fewer grain-boundaries, effective charge transport, improved crystalline quality, and reduced defect density. However, there is still no suitable epitaxial growth substrate for perovskite. Here, we developed an electrochemical lithiation intercalation and ultrasonication method to prepare high-quality antimonene nanosheets (ANs). It is found that the perovskite film grows preferentially along the (012) planes of the ANs that have perfect lattice match with the (001) planes of the perovskite, leading to a high-quality perovskite film with a preferential orientation along the [001] direction and greatly enlarged grain size. Consequently, the oriented perovskite-based PSC achieves a remarkable PCE of 24.54% and shows an enhanced stability under ambient conditions, thermal annealing or light illumination. This work opens an effective avenue to effectively control the oriented growth of perovskite film for high-performance perovskite optoelectrical devices.     

Perovskite solar cells: recent progress and strategies developed for minimizing interfacial recombination

Organometallic perovskite is a new generation photovoltaic material with exemplary properties such as high absorption co-efficient, optimal bandgap, high defect tolerance factor and long carrier diffusion length. However, suitable electrodes and charge transport materials are required to fulfill photovoltaic processes where interfaces between hole transport material/perovskite and perovskite/electron transport material are affected by phenomena of charge carrier separation, transportation, collection by the interfaces and band alignment. Based on recent available literature and several strategies for minimizing the recombination of charge carriers at the interfaces, this review addresses the properties of hole transport materials, relevant working mechanisms, and the interface engineering of perovskite solar cell (PSC) device architecture, which also provides significant insights to design and development of PSC devices with high efficiency.     

CdS多晶薄膜的制备及性质研究

分别采用近空间升华法和电子束蒸发法在透明导电玻璃和普通载玻片上制备了硫化镉(CdS)多晶薄膜.对制备样品的表征结果表明:(1)两种方法制备样品都沿(002)晶向择优生长,属于六方相多晶结构,但择优取向度不同;(2)CdS薄膜表面连续而致密,粒径均匀,但两种工艺制备样品的S:Cd原子比有较大差异;(3)CdS薄膜的光能隙在2.39～2.44eV之间,电子束蒸发制备样品光能隙稍小.分析认为,两种方法制备样品的上述差异可能与衬底温度、沉积时间及成膜机制的不同相关.