Ma Xueying, Ye Yuhui, Xiao Yang, Feng Shengnan, Zhang Chunfeng, Xia Keyu, Hu Fengrui, Xiao Min, Wang Xiaoyong
National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China.
ACS Appl Mater Interfaces. 2024 Nov 27;16(47):65142-65148. doi: 10.1021/acsami.4c12418. Epub 2024 Nov 12.
A critical issue hindering the potential applications of semiconductor mixed-halide perovskites is the phase segregation effect, wherein localized regions enriched with one type of halide anions would be formed upon continuous photogeneration of the excited-state charge carriers. These unexpected phases are capable of remixing again in the dark under the entropic driving force, the process of which is now being exclusively studied after the mixed-halide perovskites have arrived at the final stage of complete phase segregation. Here, we show that after the removal of laser excitation from a solid film of the mixed-halide perovskite nanocrystals (NCs) with partial phase segregation, the iodide- and bromide-rich regions can continuously grow in the dark for a prolonged time period of several minutes. We propose that this dark phase segregation is sustained by the local electric fields from the surface-trapped charge carriers, whose slow dissipation out of the mixed-halide perovskite NCs causes a delayed occurrence of the reversal phase remixing process.
阻碍半导体混合卤化物钙钛矿潜在应用的一个关键问题是相分离效应，即在激发态电荷载流子持续光生过程中会形成富含一种卤化物阴离子的局部区域。这些意想不到的相能够在熵驱动力作用下在黑暗中再次混合，目前在混合卤化物钙钛矿达到完全相分离的最后阶段后，正在专门研究这个过程。在这里，我们表明，在从具有部分相分离的混合卤化物钙钛矿纳米晶体（NCs）的固体薄膜中移除激光激发后，富含碘化物和溴化物的区域能够在黑暗中持续生长长达几分钟的时间。我们提出，这种暗相分离是由表面捕获的电荷载流子产生的局部电场维持的，这些电荷载流子从混合卤化物钙钛矿NCs中缓慢耗散导致了反转相再混合过程的延迟发生。
