Zhao Yixin, Nardes Alexandre M, Zhu Kai
Chemical and Materials Science Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA.
Faraday Discuss. 2014;176:301-12. doi: 10.1039/c4fd00128a. Epub 2014 Nov 19.
We report on our investigations on charge transport and recombination in TiO(2)-based mesoporous solar cells using PbI(2) and various perovskite compositions, including CH(3)NH(3)PbI(3), CH(3)NH(3)PbI(2)Br, CH(3)NH(3)PbIBr(2), and CH(3)NH(3)PbBr(3). The mesoporous TiO(2) film is about 650 nm thick. Electron microscopy measurements show that no perovskite capping layer is formed on the top surface of the TiO(2) film. Intensity-modulated photocurrent/photovoltage spectroscopies show that the electron diffusion coefficient and recombination lifetime are governed by the underlying mesoporous TiO(2) film and thus do not depend on the perovskite composition. However, replacing the perovskite absorber with PbI(2) leads to a diffusion coefficient that is about a factor of 5 slower than that in perovskite-based devices. We also find that TiCl(4) treatment of the mesoporous TiO(2) film prior to device fabrication substantially reduces the charge recombination kinetics in mesoporous perovskite solar cells.
我们报告了我们对使用PbI₂和包括CH₃NH₃PbI₃、CH₃NH₃PbI₂Br、CH₃NH₃PbIBr₂以及CH₃NH₃PbBr₃在内的各种钙钛矿组合物的TiO₂基介孔太阳能电池中的电荷传输和复合的研究。介孔TiO₂薄膜约650纳米厚。电子显微镜测量表明，在TiO₂薄膜的顶表面上未形成钙钛矿覆盖层。强度调制光电流/光电压光谱表明，电子扩散系数和复合寿命由底层的介孔TiO₂薄膜决定，因此不取决于钙钛矿组合物。然而，用PbI₂替代钙钛矿吸收剂会导致扩散系数比基于钙钛矿的器件中的扩散系数慢约5倍。我们还发现，在器件制造之前对介孔TiO₂薄膜进行TiCl₄处理可大幅降低介孔钙钛矿太阳能电池中的电荷复合动力学。
