摘要:
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/CH3NH3PbI3/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卜苯基-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.
Abstract:
The organic-inorganic metal halide perovskite materials have excellent optical and electrical properties such as high absorption coefficient,high carrier mobility,long carrier lifetime,tunable bandgap,facile fabrication process,etc.Owing to the above excellent properties,the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has increased significantly from 3.8％ to 22.1％ in the last few years.The PSCs have attracted intensive interest in recent years and show great commercial potential.Previous approaches to increasing the PCE of PSCs have focused on the optimization of the morphology of perovskite film.However,there are relatively few studies on the electron transport layer (ETL)in the typical p-i-n sandwiched structure.In this work,the PCE of PSCs with device structure of ITO/PEDTO:PSS/CH3NH3PbI3/PCBM/A1 is improved from 10.8％ to 12.5％ by using polystyrene (PS) and 1,8-diiodooctane (DIO)as binary additives during the deposition of phenyl-C61-butyric acid methyl ester (PCBM) layer.With the addition of PS,a highly smooth and uniform PCBM ETL is formed due to the increase of viscosity.The morphologies of the PCBM films prepared with and without PS are analyzed using an atomic force microscope in the tapping mode.The root-mean-square surface roughness decreases from 1.270 to 0.975 nm with the addition of PS increasing,which is more effective in preventing electron and hole from recombining at the interface between the perovskite layer and the top electrode.Addition of DIO improves the morphology of PCBM,which plays an important role in charge dissociation,charge transportation,and charge collection.From the time-resolved photoluminescence decay curves of ITO/CH3NH3PbI3/PCBM (with different additives),it is clear to conclude that the exciton dissociation between the perovskite layer and PCBM layer is faster and faster.Electrons and holes can be quickly separated,indicating that charge transport performances of electron transport layer with the addition DIO turn better.The addition of two additives is a simple and low-cost approach to improving the morphology of the electron transport layer,which provides a path-to the further improvement of the performance of p-i-n PSCs.
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