Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr3 Perovskite Nanocrystals,The Journal of Physical Chemistry C

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Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr3 Perovskite Nanocrystals
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-05-16 00:00:00 , DOI: 10.1021/acs.jpcc.8b03206
Natalie A. Gibson , Brent A. Koscher ₁ , A. Paul Alivisatos ₁ , Stephen R. Leone

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Perovskite semiconductors have emerged as a promising class of materials for optoelectronic applications. Their favorable device performances can be partly justified by the defect tolerance that originates from their electronic structure. The effect of this inherent defect tolerance, namely the absence of deep trap states, on the photoluminescence (PL) of perovskite nanocrystals (NCs) is currently not well understood. The PL emission of NCs fluctuates in time according to power law kinetics (PL intermittency, or blinking), a phenomenon that has been explored over the past two decades in a vast array of nanocrystal (NC) materials. The kinetics of the blinking process in perovskite NCs have not been widely explored. Here, PL trajectories of individual orthorhombic cesium lead bromide (CsPbBr₃) perovskite NCs are measured using a range of excitation intensities. The power law kinetics of the bright NC state are observed to truncate exponentially at long durations, with a truncation time that decreases with increasing intensity before saturating at an intensity corresponding to an average formation of a single exciton. The results indicate that a diffusion-controlled electron transfer (DCET) mechanism is the most likely charge trapping process, while Auger autoionization plays a lesser role. The relevance of the multiple recombination centers (MRC) model to the results presented here cannot be ascertained, since the underlying switching mechanism is not currently available. Further experimentation and theoretical work are needed to gain a comprehensive understanding of the photophysics in these emerging materials.

中文翻译：

CsPbBr ₃钙钛矿纳米晶体中光致发光闪烁的激发强度依赖性

钙钛矿半导体已经成为一种有前途的光电子材料。其良好的器件性能可以部分归因于其电子结构产生的缺陷容限。目前尚不十分了解这种固有的缺陷耐受性，即不存在深陷阱态，对钙钛矿纳米晶体（NCs）的光致发光（PL）的影响。NC的PL发射根据幂律动力学（PL间歇性或闪烁）随时间波动，在过去的二十年中，这种现象已在各种各样的纳米晶体（NC）材料中得到了研究。钙钛矿NCs中闪烁过程的动力学尚未得到广泛研究。在这里，单个斜方溴化铯铅（CsPbBr _3的PL轨迹钙钛矿NCs是使用一定范围的激发强度进行测量的。观察到明亮的NC状态的幂律动力学在长时间内呈指数截断，截断时间随着强度的增加而减小，然后以与单个激子的平均形成相对应的强度饱和。结果表明，扩散控制的电子转移（DCET）机制是最有可能的电荷捕获过程，而俄歇自电离的作用较小。由于目前尚不具备底层交换机制，因此无法确定多个重组中心（MRC）模型与此处显示的结果的相关性。需要进行进一步的实验和理论研究，以全面了解这些新兴材料中的光物理。

更新日期：2018-05-16

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