Kearney Kara, Seo Gabseok, Matsushima Toshinori, Adachi Chihaya, Ertekin Elif, Rockett Angus
Department of Mechanical Science and Engineering , University of Illinois , 1204 West Green Street , Urbana , Illinois 61801 , United States.
International Institute for Carbon Neutral Energy Research (WPI-I2CNER) , Kyushu University , 744 Motooka , Nishi-ku, Fukuoka 819-0395 , Japan.
J Am Chem Soc. 2018 Nov 21;140(46):15655-15660. doi: 10.1021/jacs.8b06002. Epub 2018 Nov 8.
New deposition methods of halide perovskites are being developed with the aim of improving solar cell power conversion efficiency by controlling the physiochemical properties of the perovskite film. In the case of methylammonium lead iodide (MAPbI), deep level traps limit efficiency by participating in charge carrier recombination. Prior work has shown that the solar cell efficiency of MAPbI solar cells varied significantly with deposition method; specifically, efficiencies of 13.5 and 17.7% were observed for MAPbI processed with a one- and two-step method, respectively. However, the origin of the difference in efficiency remains unclear. In this study, we analyze the interplay between deep level traps and efficiency by simulating the photoexcited charge carrier pathway across solar cells processed via the one- and two-step method using finite-element drift-diffusion modeling. We determined that in the case of one-step processing, the traps propagate throughout the bulk, while for two-step, the traps congregate at the interface where the MAPbI was grown (mesoporous TiO). Composition and structural analysis are used to propose a plausible explanation as to why the difference in processing changes the spatial distribution of the traps.
卤化物钙钛矿的新沉积方法正在不断开发，旨在通过控制钙钛矿薄膜的物理化学性质来提高太阳能电池的功率转换效率。以甲基碘化铅（MAPbI）为例，深能级陷阱通过参与电荷载流子复合来限制效率。先前的研究表明，MAPbI太阳能电池的效率会因沉积方法的不同而有显著差异；具体而言，采用一步法和两步法处理的MAPbI太阳能电池的效率分别为13.5%和17.7%。然而，效率差异的根源仍不明确。在本研究中，我们通过使用有限元漂移扩散模型模拟经一步法和两步法处理的太阳能电池中的光激发电荷载流子路径，来分析深能级陷阱与效率之间的相互作用。我们确定，在一步法处理的情况下，陷阱在整个体相中传播，而在两步法处理中，陷阱聚集在MAPbI生长的界面处（介孔TiO）。通过成分和结构分析，我们对处理方式的差异如何改变陷阱的空间分布提出了一个合理的解释。
