Elucidating the Spatial Dynamics of Charge Carriers in Quasi-Two-Dimensional Perovskites
Elucidating the Spatial Dynamics of Charge Carriers in Quasi-Two-Dimensional Perovskites
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DOI：
10.1021/acsami.1c07876
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发表时间：
2021-07-13
影响因子：
9.5
通讯作者：
Ahmadi, Mahshid
中科院分区：
文献类型：
--
作者：
Kim, Dohyung;Ahmadi, Mahshid
准二维（2D）有机-无机杂化钙钛矿（OIHP）已经显示出更好的环境稳定性和良好的太阳能电池性能。然而，准2D OIHP的功率转换效率仍然低于3D多晶钙钛矿的功率转换效率。为了了解准2D OIHP的局限性，我们使用先进的扫描探针显微镜技术探索3D和准2D钙钛矿中的电荷载流子性质。开尔文探针力显微镜（KPFM）通过测量热和潮湿条件下的光电压变化来识别准2D钙钛矿的缓慢降解。偏置驱动的光电流图获得的导电原子力显微镜（c-AFM）的测量显示局部非均匀的导电和滞后电流准2D钙钛矿，而相对均匀的导电性观察到个别晶粒在3D钙钛矿对应。此外，在横向Au电极器件中的偏压驱动KPFM和I-V测量显示出更高的电荷载流子动力学，在3D钙钛矿中的界面处具有比准2D钙钛矿器件更强的电势降。c-AFM和KPFM结果的组合证实了与3D钙钛矿相比，准2D钙钛矿中的离子导电性较低。我们的研究阐明了准2D钙钛矿的低效率背后的潜在机制，这对于进一步开发高效和稳定的基于钙钛矿的器件是必要的。
Quasi-two dimensional (2D) organic-inorganic hybrid perovskites (OIHPs) have shown better ambient stability with decent solar cell performances. However, the power conversion efficiency of quasi-2D OIHPs is still below that of 3D polycrystalline perovskites. To understand the limitation of quasi-2D OIHPs, we explore charge carrier properties in 3D and quasi-2D perovskites using advanced scanning probe microscopy techniques. Kelvin probe force microscopy (KPFM) identifies slow degradation in quasi-2D perovskites by measuring photovoltage variations under thermal and humid conditions. Bias-driven photocurrent maps obtained by conductive-atomic force microscopy (c-AFM) measurements reveal local inhomogeneous conduction and hysteretic currents in quasi-2D perovskites while relatively uniform conductivity is observed on individual grains in the 3D perovskite counterparts. In addition, bias-driven KPFM and I-V measurements in the lateral Au electrode devices show higher charge carrier dynamics with stronger potential drop at the interfaces in the 3D perovskite than those of the quasi-2D perovskite devices. The combination of c-AFM and KPFM results confirm less ionic conduction in the quasi-2D perovskites as compared to the 3D perovskites. Our study elucidates underlying mechanisms behind the lower efficiency of quasi-2D perovskites, which is necessary for further development of efficient and stable perovskite-based devices.