Highly efficient flexible perovskite solar cells with vacuum-assisted low-temperature annealed SnO2 electron transport layer

The demand for lightweight, flexible, and high-performance portable power sources urgently requires high-efficiency and stable flexible solar cells. In the case of perovskite solar cells(PSCs), most of the common electron transport layer(ETL) needs to be annealed for improving the optoelectronic properties,while conventional flexible substrates could barely stand the high temperature. Herein, a vacuumassisted annealing SnO_(2) ETL at low temperature(100℃) is utilized in flexible PSCs and achieved high efficiency of 20.14%. Meanwhile, the open-circuit voltage(V_(oc)) increases from 1.07 V to 1.14 V. The flexible PSCs also show robust bending stability with 86.8% of the initial efficiency is retained after 1000 bending cycles at a bending radius of 5 mm. X-ray photoelectron spectroscopy(XPS), atomic force microscopy(AFM), and contact angle measurements show that the density of oxygen vacancies, the surface roughness of the SnO_(2) layer, and film hydrophobicity are significantly increased, respectively. These improvements could be due to the oxygen-deficient environment in a vacuum chamber, and the rapid evaporation of solvents. The proposed vacuum-assisted low-temperature annealing method not only improves the efficiency of flexible PSCs but is also compatible and promising in the large-scale commercialization of flexible PSCs.

TiO_2 composite electron transport layers for planar perovskite solar cells by mixed spray pyrolysis with precursor solution incorporating TiO_2 nanoparticles

Perovskite solar cells with planar structure are attractive for their simplified device structure and reduced hysteresis effect. Compared to conventional mesoporous devices, TiO2 porous scaffold layers are removed in planar devices. Then, compact TiO2 electron transport layers take the functions of extracting electrons, transporting electrons, and blocking holes. Therefore, the properties of these compact TiO2 layers are important for the performance of solar cells. In this work, we develop a mixed spray pyrolysis method for producing compact TiO2 layers by incorporating TiO2 nanoparticles with dif- ferent size into the precursor solutions. For the optimized nanoparticle size of 60 nm, a power conversion efficiency of 16.7% is achieved, which is obviously higher than that of devices without incorporated nanoparticles （9.9%）. Further in- vestigation reveals that the incorporation of nanoparticles can remarkably improve the charge extraction and recombination processes.

Progress in hole-transporting materials for perovskite solar cells

In recent years the photovoltaic community has witnessed the unprecedented development of perovskite solar cells（PSCs） as they have taken the lead in emergent photovoltaic technologies. The power conversion efficiency of this new class of solar cells has been increased to a point where they are beginning to compete with more established technologies. Although PSCs have evolved a variety of structures, the use of hole-transporting materials（HTMs） remains indispensable. Here, an overview of the various types of available HTMs is presented. This includes organic and inorganic HTMs and is presented alongside recent progress in associated aspects of PSCs, including device architectures and fabrication techniques to produce high-quality perovskite films. The structure, electrochemistry, and physical properties of a variety of HTMs are discussed, highlighting considerations for those designing new HTMs. Finally, an outlook is presented to provide more concrete direction for the development and optimization of HTMs for highefficiency PSCs.

Interface Modification of TiO_(2)Electron Transport Layer with PbCl_(2)for Perovskiote Solar Cells with Carbon Electrode

Perovskite Solar Cells(PSCs)have attracted considerable attention because of their unique features and high efficiency.However,the stability of perovskite solar cells remains to be improved.In this study,we modified the TiO_(2)Electron Transport Layer(ETL)interface with PbCl_(2).The efficiency of the perovskite solar cells with carbon electrodes increased from 11.28%to 13.34%,and their stability obviously improved.The addition of PbCl_(2)had no effect on the morphology,crystal structure,and absorption property of the perovskite absorber layer.However,it affected the band energy level alignment of the solar cells and accelerated the electron extraction and transfer at the interface between the perovskite layer and the ETL,thus enhancing the overall photovoltaic performance.The interfacial modification of ETL with PbCl_(2)is a promising way for the potential commercialization of low-cost carbon electrode-based perovskite solar cells.

Thick Active-Layer Organic Solar Cells

Organic solar cells(OSCs)present a promising renewable energy technology due to their cost-effectiveness,adaptability,and lightweight nature.The advent of non-fullerene acceptors has further boosted their significance,allowing for power conversion efficiencies surpassing 19%even with an active layer thickness of about 100 nm.However,in order to achieve large scale production,it is necessary to fabricate OSCs with thicker active layers exceeding 300 nm that are compatible with large-area printing techniques.Nevertheless,OSCs with thick active layers have inferior performance compared to those with thin active layers.To expedite the transition of OSCs from laboratory to industrial high-throughput manufacturing,considerable efforts have been made to comprehend the performance limitations of thick active-layer OSCs,develop novel photoactive materials that are high-performance and tolerant towards the thickness of the active layer,and optimize the morphology of the photoactive layer and device structure.This review aims to provide a comprehensive summary of the mechanisms that lead to efficiency loss in thick active-layer OSCs,the representative works on molecular design,and the optimization strategies for high-performance thick active-layer OSCs,and the remaining challenges that must be addressed.

基于双层电子传输层钙钛矿太阳能电池的物理机制

近年来基于钙钛矿材料的太阳能电池以其优异的光电转换效率,成为了最具有发展潜力的光伏器件.受制于制备工艺及界面传输层的材料,钙钛矿太阳能电池存在体内、界面缺陷和能级错位等问题,导致非辐射复合损耗增加,妨碍其效率进一步提升及工作稳定性.因此,降低能级错位及界面缺陷态等损耗对于实现高效钙钛矿太阳能电池至关重要.本文研究了钙钛矿太阳能电池中双层电子传输层及其阶梯状导带结构对器件性能的影响,揭示了活性层与传输层之间的导带偏移量对两者之间界面复合及性能提升的机理.另外,研究了体内与界面缺陷态密度对单层及双层电子传输层结构下电池性能的影响,发现在高缺陷态密度下,双层结构比单层结构具有更高的效率.研究表明双层电子传输层结构不仅能改善界面能级错位损耗,还可以降低电池性能受体内及界面缺陷影响,对制备高性能太阳能电池具有指导意义.

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.

钙钛矿太阳能电池中的二氧化锡电子传输层调控

作为平面异质结钙钛矿太阳能电池(PSCs)的重要组成部分,电子传输层(ETL)在提升PSCs器件的性能和稳定性上起着重要的作用。尽管最常用的两类ETL材料——二氧化钛(TiO_(2))和二氧化锡(SnO_(2)),均以纳米颗粒和溶液方式制备,TiO_(2)却面临着电子迁移率低、器件滞回效应大、化学稳定性差、需高温制备等问题,相比之下,SnO_(2)具有优异的光电学性质、更高的稳定性、可低温制备等优势。聚焦于基于SnO_(2)ETL的PSCs稳定性和界面电荷提取,首先综述了SnO_(2)材料的物理性质和优点;然后从制备和成膜方法(如化学浴沉积、溶液旋涂等)入手,进一步阐明了SnO_(2)的体相和表面缺陷;最后基于SnO_(2)ETL的缺陷,从界面钝化、体相掺杂和双电子层构筑等三方面重点介绍了提升PSCs稳定性和界面载流子提取效率的途径。该综述可助力PSCs性能和稳定性的进一步提升,为该新兴光伏技术进一步实用化贡献有用的见解。

介孔TiO2结构在CH3NH3PbI3钙钛矿太阳能电池中的作用

平面结构和介孔结构是钙钛矿太阳能电池通常采用的两种器件结构.然而,不同器件结构如何影响器件性能仍有待进一步深入研究.文献中关于哪种结构更加理想的研究报道不尽一致;特别是,介孔TiO2层的具体作用仍待进一步阐明.在本研究中,我们通过细致对比研究两种器件结构中的钙钛矿薄膜特性与电池光伏性能,揭示了介孔TiO2结构在CH3NH3PbI3钙钛矿太阳能电池中的具体作用.晶体结构、微观形貌、光学和电学性能等系统表征表明,介孔TiO2结构有助于增大钙钛矿晶体尺寸、增加薄膜光捕获、提高电子提取及抑制电荷复合.与平面结构相比,介孔结构器件的效率更高(18.18%),迟滞更小.本研究揭示了钙钛矿太阳能电池中介孔TiO2结构的作用,可为高性能太阳能电池的器件结构设计和优化提供理论指导.