有机无机杂化固态太阳能电池的研究进展

近年来, 由于钙钛矿材料优良的光学吸收和电荷传导特性, 有机无机杂化固态太阳能电池取得了突破性的进展. 自2009年首次报道了光电转换效率为3.8%的钙钛矿太阳能电池以来, 该类电池的效率不断突破. 基于介孔薄膜的电池已取得了超过16.7%的认证光电转换效率, 基于平板异质结结构电池光电转换效率达到19.3%, 已接近传统硅基太阳能电池的光电转换效率. 本文将介绍有机无机杂化钙钛矿作为光电材料的光学物理结构特性, 以及在固态太阳能电池中的应用. 基于固态钙钛矿太阳能电池结构上的差异, 分别介绍其在多孔结构、平板异质结结构、柔性结构以及无空穴传导材料结构电池工作特性和各自优势, 以及影响电池特性的主要影响因素, 特别是钙钛矿成膜控制等. 并阐述对钙钛矿电池的理解和进一步提高固态钙钛矿电池光电转换效率需要关注的重点以及展望.     

二硫化钨纳米片制备及其钙钛矿太阳能电池空穴传输层应用

开发新型无机空穴传输层材料是钙钛矿电池实现商业应用的重要挑战之一。本文开展了二硫化钨纳米片制备及其钙钛矿太阳能电池空穴传输层应用研究。采用液相超声剥离法成功制备了WS 2纳米片,并将其引入钙钛矿太阳能电池中用作空穴传输层。结果表明,当WS 2纳米片溶液浓度为1 mg/mL时,制备的WS 2纳米片空穴传输层具有较合适的厚度,并且后续在其上生长的钙钛矿活性层成膜质量高、结晶性能好,电池取得6.3%的光电转换效率。结果证实WS 2纳米片可作为新型无机空穴传输层材料用于钙钛矿太阳能电池。     

钙钛矿太阳能电池近期进展

近几年来,基于有机无机金属卤化物钙钛矿(ABX_3)的太阳能电池由于其独特的物理化学性质受到了广泛的关注.这种钙钛矿材料具有很高的消光系数、较强的电荷传递能力、长的载流子寿命、长的载流子扩散距离以及特殊的双极性,同时低成本易制作.自2009年至今,钙钛矿太阳能电池的光电转换效率从最初的3.8%增长到了20.8%,使之成为最有可能在未来代替传统单晶硅太阳能电池的新型太阳能电池.同时,由于钙钛矿具有双极性,故钙钛矿太阳能电池的结构也有多种,最常见的结构有介孔结构、平面结构、介观超结构、无空穴传输层结构等.本文主要介绍钙钛矿太阳能电池的发展、电池结构及其对光电池性能的影响、钙钛矿薄膜的制备方法,同时探讨了钙钛矿在电子传输层上的吸附模型和电荷在电池界面中的传输机理以及界面工程,并介绍该类型电池在近期所获得的突破及未来可能的发展方向,以便对钙钛矿太阳能电池有进一步的了解.     

n-i-p结构钙钛矿太阳能电池界面钝化的研究进展

近年来有机-无机杂化钙钛矿材料因其吸收系数高、成本低廉、制备工艺简单等优点吸引了大批科研人员进行研究,目前在实验室制备的电池能量转换效率已经超过23%.钙钛矿太阳能电池一般采用溶液法逐层制备,在此过程中由于退火温度、结晶速率等因素的影响,钙钛矿内部以及界面会产生大量的缺陷,这些缺陷会增加载流子复合概率,降低载流子寿命,严重影响钙钛矿太阳能电池的性能.因此研究和理解钙钛矿的缺陷对制备高效钙钛矿太阳能电池至关重要.本文讨论了在正式结构中,钙钛矿太阳能电池缺陷的产生以及缺陷对钙钛矿太阳能电池的影响,分析了不同材料钝化电子传输层/钙钛矿层界面以及钙钛矿层/空穴传输层界面缺陷的机理,对比了不同钝化材料对钙钛矿太阳能电池光伏性能的影响,总结了界面钝化材料在钙钛矿太阳能电池中的作用.最后指出了钙钛矿太阳能电池钝化缺陷的研究趋势和发展方向.     

锡基钙钛矿太阳能电池载流子传输层的探讨

锡基钙钛矿太阳能电池可避免铅元素对环境带来的污染,近年来已成为光伏领域的研究热点.本文以SCAPS-1D太阳能电池数值模拟软件为平台,对不同电子传输层和不同空穴传输层的锡基钙钛矿太阳能电池器件的性能进行数值仿真对比,从理论上分析不同载流子传输层的锡基钙钛矿太阳能电池的性能差异.结果显示,载流子传输层与钙钛矿层的能带对齐对电池性能至关重要.电子传输层具有更高的导带或电子准费米能级以及空穴传输层具有更低的价带或空穴准费米能级时,对电池输出更大的开路电压有促进作用.另外,当电子传输层的导带高于钙钛矿层导带或钙钛矿层的价带高于空穴传输层的价带时,钙钛矿层与载流子传输层界面形成spike势垒,界面复合机制相对较弱,促使电池获得更佳的性能.当Cd0.5Zn0.5S和MASnBr3分别作为电子传输层和空穴传输层时,与其他材料相比,获得了更优的输出特性:开路电压Voc=0.94 V,短路电流密度Jsc=30.35 mA/cm^2,填充因子FF=76.65%,功率转换效率PCE=21.55%,可认为Cd0.5Zn0.5S和MASnBr3是设计锡基钙钛矿太阳能电池结构合适的载流子传输层材料.这些模拟结果有助于实验上设计并制备高性能的锡基钙钦矿太阳能电池.     

钙钛矿太阳能电池中电子传输材料的研究进展

有机-无机杂化的卤素钙钛矿材料在2009年首次应用在光伏器件中, 而后有关此类型太阳能电池的报道数量呈井喷式增长. 至2014年5月钙钛矿电池光电转化效率已接近20%, 已超过有机及染料敏化太阳能电池的效率, 且有望达到单晶硅太阳能的水平, 成为光伏发电领域中的希望之星. 在钙钛矿电池中, 电子传输材料与吸收层的电子选择性接触对提高光电转化效率起到重要作用, 尤其在正置结构器件中, 电子传输层的介观结构直接影响钙钛矿的生长情况. 同时, 电子传输层的化学性质及其界面也会对电池的稳定性和寿命产生影响. 本文总结了电子传输材料在该类电池中的研究现状和热点, 并按材料的化学组分不同, 将电子传输材料分为三类: 金属氧化物、有机小分子和复合材料, 详细地介绍了电子传输材料在钙钛矿太阳能电池中的作用和近来的最新进展.     

平面异质结有机-无机杂化钙钛矿太阳电池研究进展

高效低成本太阳电池的研发是太阳能光伏技术大规模推广应用的关键. 近年来兴起的有机- 无机杂化钙钛矿(以下简称钙钛矿)太阳电池因具有光电能量转换效率高、制备工艺简单等优点, 引起了学术界和产业界的广泛关注, 具有广阔的发展前景. 其中平面异质结钙钛矿太阳电池因具有结构简单, 可低温制备等诸多优点, 成为目前研究的一个重要方向. 平面异质结钙钛矿太阳电池分为n-i-p型和p-i-n型两种结构. 其中钙钛矿分别与电子传输层和空穴传输层形成两个界面, 在这两个界面上实现电子和空穴的快速分离. 电子传输层和空穴传输层分别为电子和空穴提供了独立的输运通道. 平面异质结结构有利于钙钛矿太阳电池中电子和空穴的分离、传输和收集. 此外, 该结构不需要高温烧结的多孔结构氧化物骨架, 扩大了电子和空穴传输材料的选择范围. 可以根据钙钛矿材料的能带分布及载流子传输特性, 来选择能级和载流子传输速率更为匹配的传输材料. 本文对钙钛矿的材料特性, 平面异质结结构的由来及发展进行了简要的概述. 其中重点介绍了平面异质结钙钛矿太阳电池的结构特征、工作机理、钙钛矿/电荷传输层的界面特性, 以及电池性能的优化, 包括钙钛矿薄膜制备、空穴和电子传输层的优化等. 最后对钙钛矿电池的发展前景及存在问题进行了阐述, 为今后高效、稳定钙钛矿太阳电池的研究提供参考.     

双添加剂处理电子传输层富勒烯衍生物[6,6]-苯基-C61丁酸甲酯对钙钛矿太阳能电池性能的影响

有机无机复合钙钛矿材料被证明是非常出色的光伏材料,目前主要通过优化钙钛矿材料的结晶和形貌来提高钙钛矿太阳能电池的效率.而对于电荷传输层,特别是p-i-n结构中电子传输层的研究相对较少.因此,本文制备了结构为ITO/PEDOT:PSS/CH3NH3Pb I3/PCBM/Al的钙钛矿太阳能电池通过在电子传输层富勒烯衍生物[6,6]-苯基-C61丁酸甲酯(PCBM)中添加聚苯乙烯(PS)和1,8-二碘辛烷(DIO)使得钙钛矿太阳能电池的光电转换效率从10.8%提升到了12.5%.分析了性能提高的原因主要是:1)添加剂PS的加入提升了PCBM的黏度,从而形成了质量更高、更平滑的膜层,这有利于抑制电子和空穴在钙钛矿层和电子传输层之间的复合;2)添加剂DIO的加入改善了电子传输层的形貌,有利于电荷的分离、传输和收集.研究结果表明用成本较低的添加剂处理可以改善电子传输层的形貌和膜层的质量达到了改善电荷传输特性的效果提升了钙钛矿太阳能电池的效率为提升钙钛矿太阳能电池性能提供了一条可行的路径.     

新型碳材料在钙钛矿太阳电池中的应用研究进展

新型碳材料如石墨烯及其氧化物、碳纳米管、富勒烯及石墨炔等因其优异的热学、力学、电学、光学性能成为了钙钛矿太阳电池研究的又一亮点. 本文总结了新型碳材料在钙钛矿太阳电池对电极、电子传输材料及空穴传输材料中的研究进展, 新型碳材料的引入有效地提高了钙钛矿电池的性能, 为下一步新型碳材料的应用开发以及钙钛矿电池器件的研究提供了新的思路.     

影响杂化钙钛矿太阳能电池稳定性的因素探讨

自从2009年首次报道采用有机-无机杂化钙钛矿作为吸光材料用于太阳能电池以来, 钙钛矿太阳能电池效率的快速提升引起了人们广泛的关注, 这类电池同时具有制备工艺简单、成本低廉等优点, 引发了钙钛矿电池的研究热潮. 目前研究工作大多数集中在如何提高电池的光电转化效率, 但钙钛矿电池要真正实现产业化应用, 急需要解决材料及器件的稳定性问题. 本文探讨影响钙钛矿材料及器件的稳定性因素, 从温度及湿度等方面分析了材料的稳定性, 从传输材料及其界面问题讨论了器件的稳定性.     

高效率钙钛矿太阳电池发展中的关键问题

钙钛矿太阳电池的迅速发展为解决未来能源问题带来一线曙光. 但是, 钙钛矿太阳电池在高效率电池器件的可重现性、稳定性以及性能评估等方面还面临着很多问题, 严重制约其今后的发展. 本文综述了钙钛矿太阳电池面世以来发生的重要进展, 以及存在的几个关键性问题. 从器件基本结构和基本工作原理出发, 本文重点讨论了光吸收层的光谱和形貌等性质对器件性能和可重现性的影响, 阐明了电子传输层和空穴阻隔层的重要作用, 论述了空穴传输层的相关进展以及其对器件稳定性的影响. 通过对以上关键问题的讨论和总结, 本文对钙钛矿太阳电池未来的研究发展进行了展望.     

CH3NH3PbI3/poly‐3‐hexylthiophen perovskite mesoscopic solar cells: Performance enhancement by Li‐assisted hole conduction

To address if the non‐triphenylamine derivative hole transporting materials such as P3HT (poly‐3‐hexylthiophene) could also exhibit high device efficiency in mesoscopic MAPbI₃ perovskite solar cells, we examined the effect of Li‐TFSI (Li‐bis(trifluoromethanesulfonyl) imide) and t‐BP (4‐tert‐butylpyridine) additives added in P3HT on device performance. Unlike the triphenylamine HTMs, the P3HT thiophene HTM without amine moiety was not doped by the additives but its conductivity was significantly improved by the Li‐TFSI/t‐BP mediated additional hole conduction. By inclusion of Li‐TFSI/t‐BP additive, we could fabricate more efficient mesoscopic MAPbI₃ perovskite solar cells with smaller hysteresis with respect to scan direction due to Li mediated additional hole conduction. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Low-temperature-processed ZnO thin films as electron transporting layer to achieve stable perovskite solar cells

Morphology and surface property of ZnO thin films as electron transporting layer in perovskite solar cells are crucial for obtaining high-efficient and stable perovskite solar cells. In this work, two different preparation methods of ZnO thin films were carried out and the photovoltaic performances of the subsequent perovskite solar cells were investigated. ZnO thin film prepared by sol–gel method was homogenous but provided high series resistance in solar cells, leading to low short circuit current density. Lower series resistance of solar cell was obtained from homogeneous ZnO thin film from spin-coating of colloidal ZnO nanoparticles (synthesized by hydrolysis–condensation) in a mixture of 1-butanol, chloroform and methanol. The perovskite solar cells using this film achieved the highest power conversion efficiency (PCE) of 4.79% when poly(3-hexylthiophene) was used as a hole transporting layer. In addition, the stability of perovskite solar cells was also examined by measuring the photovoltaic characteristic for six consecutive weeks with the interval of 2 weeks. It was found that using double layers of the sol–gel ZnO and ZnO nanoparticles provided better stability with no degradation of PCE in 10 weeks. Therefore, this work provides a simple method for preparing homogeneous ZnO thin films in order to achieve stable perovskite solar cells, also for controlling their surface properties which help better understand the characteristics of perovskite solar cells.     

Highly efficient perovskite solar cells by tuning electronic structures of thienothiophene-based as hole transport materials

The atomic substitutions were used to study the hole transport materials (HTM) properties of six thiophenothiophene molecules (HTM1-HTM6) to reveal the relationship between their core structures and photoelectric properties. To better investigate the difference between experimentally original and designed molecules, we calculated the hole mobility and some parameters (such as energy levels, stability, and optical properties, etc). The results showed that the molecular orbital levels of the original and designed molecules have well matched with perovskite and Ag electrode to ensure hole transport and inhibit the electron reflux. Among the designed HTMs, HTM5 has the smallest energy gap that results in the red-shifted absorption spectra. Furthermore, there is an obviously increased charge transfer integral V due to the introduction of the Si atom, which greatly improved the hole mobility. Therefore, atom substitution by introducing Si atoms (HTM5) will improve the energy levels and charge transport ability, and molecular design by means of atom substitution can be a potential way to tunable HTM performance in solar cells.     

应用于钙钛矿太阳能电池中金属氧化物电子传输材料的研究进展

基于有机金属卤化铅钙钛矿材料作为光活性层的太阳能电池(PSCs)已经获得了25.2%的认证效率,是除硅基太阳能电池外被认为最有可能实现商业化的太阳能电池之一。电子传输层是PSCs器件结构的最基本组成之一,其构成材料与光活性层的成膜质量、界面电荷的快速提取以及能级匹配等密切相关。因而,电子传输材料在PSCs的光伏性能及稳定性调控方面发挥着重要作用。本文对应用在PSCs中的金属氧化物电子传输材料进行了回顾与总结,着重强调了材料的纳米结构与制备工艺、半导体特性与分类以及掺杂与界面修饰等方面的研究进展,并对其今后的发展进行了展望。     

Inverted structure perovskite solar cells: A theoretical study

We analysed perovskite CH₃NH₃PbI_3-xCl_x inverted planer structure solar cell with nickel oxide (NiO) and spiro-MeOTAD as hole conductors. This structure is free from electron transport layer. The thickness is optimized for NiO and spiro-MeOTAD hole conducting materials and the devices do not exhibit any significant variation for both hole transport materials. The back metal contact work function is varied for NiO hole conductor and observed that Ni and Co metals may be suitable back contacts for efficient carrier dynamics. The solar photovoltaic response showed a linear decrease in efficiency with increasing temperature. The electron affinity and band gap of transparent conducting oxide and NiO layers are varied to understand their impact on conduction and valence band offsets. A range of suitable band gap and electron affinity values are found essential for efficient device performance.     

Searching of new,cheap, air- and thermally stable hole transporting materials for perovskite solar cells

In this work, two thermal- and air-stable, hole transporting materials (HTM) in perovskite solar cells are analyzed. Those obtained and investigated materials were two polyazomethines: the first one with three thiophene rings and 3,3′-dimethoxybenzidine moieties (S9) and the second one with three thiophene rings and fluorene moieties (S7). Furthermore, presented polyazomethines were characterized by Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, atomic force microscopy (AFM) and thermogravimetric analysis (TGA) experiments. Both polyazomethines (S7 and S9) possessed good thermal stability with a 5% weight loss at 406 and 377 °C, respectively. The conductivity of S7 was two orders of magnitude higher than for S9 polymer (2.7 × 10^?8 S/cm, and 2.6 × 10^?10 S/cm, respectively). Moreover, polyazomethine S9 exhibited 31 nm bathochromic shift of the absorption band maximum compared to S7.Obtained perovskite was investigated by UV–vis and XRD. Electrical parameters of perovskite solar cells (PSC) were investigated at Standard Test Conditions (STC). It was found that both polyazomethines protect perovskite which is confirmed by ageing test where V_oc did not decrease significantly for solar cells with HTM in contrast to solar cell without hole conductor, where V_oc decrease was substantial. The best photoconversion efficiency (PCE = 6.9%), among two investigated in this work polyazomethines, was obtained for device with the following architectures FTO/TiO₂/TiO₂ + perovskite/S7/Au. Stability test proved the procreative effects of polyazomethines on perovskite absorber.     

Nano Ag-enhanced photoelectric conversion efficiency in all-inorganic,hole-transporting-layer-free CsPbIBr2 perovskite solar cells

All-inorganic, hole-transporting-layer-free CsPbIBr₂ perovskite solar cells have great potential for development, but their device performance needs to be further improved. Recently, metal nanostructures have been successfully applied in the field of solar cells to improve their performance. Nano Ag-enhanced power conversion efficiency (PCE) in one CsPbIBr₂ perovskite solar cell utilizing localized surface plasmons of Ag nanoparticles (NPs) on the surface has been researched experimentally and by simulation in this paper. The localized surface plasmon resonance of Ag NPs has a near-field enhancement effect, which is expected to improve the light absorption of CsPbIBr₂ perovskite photovoltaic devices. In addition, Ag NPs have a forward-scattering effect on the incident light, which can also improve the performance of CsPbIBr₂-based perovskite photovoltaic devices. By directly assembling Ag NPs (with a size of about 150 nm) on the surface of fluorine-doped tin oxide it is found when the particle surface coverage is 10%, the CsPbIBr₂ perovskite photovoltaic device achieves a best PCE of 2.7%, which is 9.76% higher than that of the control group. Without changing any existing structure in the ready-made solar cell, this facile and efficient method has huge applications. To the best of our knowledge, this paper is the first report on nano Ag-enhanced photoelectric conversion efficiency in this kind of CsPbIBr₂ perovskite solar cell.     

新型高效聚合物/富勒烯有机光伏电池研究进展

有机聚合物/富勒烯本体异质结光伏电池以其不断提高的能量转换效率受到了研究人员的广泛关注, 近年来成为光伏电池研究领域的热点之一. 本文主要通过对聚合物/富勒烯太阳能电池的内部机理,包括光吸收、激子扩散和解离以及自由载流子输运和提取等关键科学问题, 从器件材料和结构优化、形貌控制和界面修饰等不同侧面介绍了提高聚合物/富勒烯太阳能电池性能的方法, 讨论了各种器件的结构和能量转换效率, 对于进一步开展这方面的研究工作指明了方向, 最后对其未来的发展前景做出了展望.     

Efficient design of perovskite solar cell using mixed halide and copper oxide

Solar cells based on perovskites have emerged as a transpiring technology in the field of photovoltaic. These cells exhibit high power conversion efficiency. The perovskite material is observed to have good absorption in the entire visible spectrum which can be well illustrated by the quantum efficiency curve. In this paper, theoretical analysis has been done through device simulation for designing solar cell based on mixed halide perovskite. Various parameters have efficacy on the solar cell efficiency such as defect density, layer thickness, doping concentration, band offsets, etc. The use of copper oxide as the hole transport material has been analyzed. The analysis divulges that due to its mobility of charge carriers, it can be used as an alternative to spiro-OMeTAD. With the help of simulations, reasonable materials have been employed for the optimal design of solar cell based on perovskite material. With the integration of copper oxide into the solar cell structure, the results obtained are competent enough. The simulations have shown that with the use of copper oxide as hole transport material with mixed halide perovskite as absorber, the power conversion efficiency has improved by 6%.The open circuit voltage has shown an increase of 0.09 V, short circuit current density has increased by 2.32 m A/cm~2, and improvement in fill factor is 8.75%.