Chirvony Vladimir S, Martínez-Pastor Juan P
J Phys Chem Lett. 2018 Sep 6;9(17):4955-4962. doi: 10.1021/acs.jpclett.8b01241. Epub 2018 Aug 16.
Interpretation of the photoluminescence (PL) decay kinetics in metal halide perovskites (MHPs) is extremely important for understanding the mechanisms and control of charge recombination in these promising photovoltaic and optoelectronic materials. In this work, we give a review of current models describing the PL decay kinetics in MHP layers and nanocrystals with particular attention to the interpretation of long-lived PL decay components (hundreds of nanoseconds to microseconds). First, we analyze phenomenological photophysical models based on the rate equations, which describe the charge carrier recombination in MHP layers as an exclusively intrinsic bulk process. An important role of the carrier diffusion and nonradiative recombination on the layer surfaces is then discussed. A recently published approach is then analyzed, in the framework of which the observed long-lived components of PL decay kinetics in MHP nanocrystals are described in terms of the delayed luminescence mechanism arising due to the processes of multiple trapping and detrapping of carriers by shallow nonquenching traps. The possible origin of the shallow traps and perspectives to include the carrier trapping and detrapping processes in a model describing PL kinetics in MHP layers are discussed.
对于理解这些有前景的光伏和光电子材料中的电荷复合机制及控制而言，解释金属卤化物钙钛矿（MHP）中的光致发光（PL）衰减动力学极为重要。在这项工作中，我们对描述MHP层和纳米晶体中PL衰减动力学的当前模型进行了综述，特别关注长寿命PL衰减分量（数百纳秒至微秒）的解释。首先，我们分析基于速率方程的唯象光物理模型，该模型将MHP层中的电荷载流子复合描述为完全是本征体相过程。然后讨论了载流子扩散和层表面非辐射复合的重要作用。接着分析了最近发表的一种方法，在此框架下，MHP纳米晶体中观察到的PL衰减动力学的长寿命分量是根据浅非猝灭陷阱对载流子的多次俘获和脱俘获过程引起的延迟发光机制来描述的。讨论了浅陷阱的可能起源以及在描述MHP层中PL动力学的模型中纳入载流子俘获和脱俘获过程的前景。
