Lin Ping, Meng Qingyu, Chen Hang, Hu Haihua, Fang Desheng, Xu Lingbo, Wang Peng, Cui Can
Key Laboratory of Optical Field Manipulation of Zhejiang Province, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, People's Republic of China.
Zhejiang University City College, Hangzhou 310015, People's Republic of China.
J Phys Condens Matter. 2021 Jun 3;33(28). doi: 10.1088/1361-648X/abff92.
High-quality MAPb(= I, Br, Cl) single crystals with a desirable size were grown through an inverse temperature crystallization method. Systematically measurements of current-voltage (-) hysteresis show that the hysteresis is strongly dependent on the measuring protocol, including scan rate and light illumination condition, which reveals the competition of three main factors that influence the charge dynamics in different regimes, defect trap, MAdipoles rotation, and ion migration. In the dark, defect trapping is the dominant charge transport dynamics at low bias in the MAPbI, while the MAdipole rotation is significant in MAPbBr, and ion migration occurs in MAPbCl. However, as bias increases, MAdipole rotation plays a crucial role in the conductivity either in the dark or under light illumination. The time-dependent photoresponse exhibits different tendencies under various biases. The slow rising dynamics of photoresponse in MAPbis attributed to the slow rotation of MAdipoles, while an immediate overshoot followed by a decay suggests significant ion migration contribution at high external bias. The results serve as comprehensive experimental support to understand the hysteresis behaviors and slow photoresponse in MAPb, particularly in MAPbCl, and provide a guide for future work in MAPbbased optoelectronic devices.
通过逆温结晶法生长出了具有理想尺寸的高质量MAPb(=I, Br, Cl)单晶。对电流-电压(-)滞后现象的系统测量表明，滞后现象强烈依赖于测量协议，包括扫描速率和光照条件，这揭示了影响不同区域电荷动力学的三个主要因素之间的竞争，即缺陷陷阱、MA偶极子旋转和离子迁移。在黑暗中，缺陷俘获是MAPbI中低偏压下的主要电荷传输动力学，而MA偶极子旋转在MAPbBr中很显著，离子迁移发生在MAPbCl中。然而，随着偏压增加，MA偶极子旋转在黑暗或光照条件下的电导率中都起着关键作用。随时间变化的光响应在不同偏压下呈现出不同的趋势。MAPb中光响应的缓慢上升动力学归因于MA偶极子的缓慢旋转，而在高外部偏压下，立即出现过冲随后衰减表明离子迁移贡献显著。这些结果为理解MAPb尤其是MAPbCl中的滞后行为和缓慢光响应提供了全面的实验支持，并为基于MAPb的光电器件的未来工作提供了指导。
