Jiang Huirong, Liu Xingyu, Chai Nianyao, Huang Fuzhi, Peng Yong, Zhong Jie, Zhang Qi, Ku Zhiliang, Cheng Yi-Bing
State Key Laboratory of Advanced Technologies for Materials Synthesis and Processing, International School of Materials Science and Engineering, Wuhan University of Technology 122 Luoshi Road Wuhan Hubei P. R. China
School of Aerospace, Transport and Manufacturing, Cranfield University Cranfield, Bedfordshire MK430AL UK
RSC Adv. 2018 Oct 15;8(61):35157-35161. doi: 10.1039/c8ra04347g. eCollection 2018 Oct 10.
The hysteretic phenomenon commonly exists in the - curves of perovskite solar cells with different structures, especially for carbon-based mesoscopic perovskite solar cells without hole-conductor (carbon-based PSCs). By adding moderate amounts of methylammonium chloride (MACl) into MAPbI perovskite precursor, we found the - hysteresis of carbon-based PSCs could be significantly alleviated and the crystallinity of MAPbI perovskite could also be influenced. With the increasing amount of MACl, MAPbI perovskite showed better and better crystallinity until the MACl came to 0.45 M. The champion device with 0.45 M of additional MACl exhibited a preferable PCE of 14.27% for reverse-scan (RS) and 14.50% for forward-scan (FS), significantly higher than that of the pristine device (8.74% for RS and 4.80% for FS). What's more, the - hysteretic index of the device gradually decreased along with the increasing amount of MACl, and kept at low value even when the crystallinity of MAPbI perovskite became poor. Through XRD and PL analysis, we demonstrated that the recombination rate of the accumulated charges at the perovskite/TiO interface is the main reason for photocurrent hysteresis in carbon-based PSCs. High quality of perovskite crystals is an important contributing factor for high-performance PSCs with low hysteresis, but there is no necessary correlation between low hysteresis and good crystallinity. This research presents an effective way to fabricate carbon-based PSCs with low-hysteresis, and at the same time, provides evidence for investigating the origin of - hysteresis of PSCs.
迟滞现象普遍存在于不同结构的钙钛矿太阳能电池的J - V曲线中，尤其是对于没有空穴导体的碳基介观钙钛矿太阳能电池（碳基PSC）。通过向MAPbI钙钛矿前驱体中添加适量的甲基氯化铵（MACl），我们发现碳基PSC的J - V迟滞现象可以得到显著缓解，并且MAPbI钙钛矿的结晶度也会受到影响。随着MACl含量的增加，MAPbI钙钛矿的结晶度越来越好，直到MACl含量达到0.45 M。添加0.45 M MACl的冠军器件在反向扫描（RS）时表现出较好的光电转换效率（PCE），为14.27%，正向扫描（FS）时为14.50%，显著高于原始器件（RS时为8.74%，FS时为4.80%）。此外，器件的J - V迟滞指数随着MACl含量的增加而逐渐降低，即使MAPbI钙钛矿的结晶度变差时也保持在较低值。通过X射线衍射（XRD）和光致发光（PL）分析，我们证明了钙钛矿/TiO₂界面处积累电荷的复合率是碳基PSC中光电流迟滞的主要原因。高质量的钙钛矿晶体是具有低迟滞的高性能PSC的一个重要因素，但低迟滞与良好的结晶度之间没有必然的关联。本研究提出了一种制备低迟滞碳基PSC的有效方法，同时为研究PSC的J - V迟滞起源提供了依据。
