Kim Taehee, Jung Seok Il, Ham Sujin, Chung Heejae, Kim Dongho
Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, 120-749, Seoul, Korea.
Inorganic Materials Lab, Samsung Advanced Institute of Technology, 16678, Suwon, Gyeonggi-do, Korea.
Small. 2019 Aug;15(33):e1900355. doi: 10.1002/smll.201900355. Epub 2019 Jun 25.
Halide perovskites (ABX ) have emerged as promising materials in the past decade owing to their superior photophysical properties, rendering them potential candidates as solar cells, light-emitting diode displays, and lasing materials. To optimize their utilization into optoelectronic devices, fundamental understanding of the optical behaviors is necessary. To reveal the comprehensive structure-property relationship, CH NH PbBr (MAPbBr ) perovskite quantum dots (PQDs) of three different sizes are prepared by controlling the precipitation temperature. Photoluminescence (PL) blinking, a key process that governs the emission efficiency of the PQD materials, is investigated in detail by the time-resolved spectroscopic measurements of individual dots. The nature of the generated species in the course of blinking events is identified, and the mechanism governing the PL blinking is studied as a function of PQD sizes. Further, the practical applicability of MAPbBr PQDs is assessed by studying the multiexciton dynamics under high photoexcitation intensity under which most of the display devices work. Ultrafast transient absorption spectroscopy helped in uncovering the volume-dependent Auger recombination rates, which are further explored by comparing the early-time transitions related to surface trap states and higher band states.
卤化物钙钛矿（ABX₃）在过去十年中已成为有前景的材料，这得益于其卓越的光物理性质，使其成为太阳能电池、发光二极管显示器和激光材料的潜在候选者。为了优化它们在光电器件中的应用，有必要对其光学行为有基本的了解。为了揭示全面的结构-性能关系，通过控制沉淀温度制备了三种不同尺寸的CH₃NH₃PbBr₃（MAPbBr₃）钙钛矿量子点（PQD）。通过对单个量子点的时间分辨光谱测量，详细研究了光致发光（PL）闪烁，这是一个控制PQD材料发射效率的关键过程。确定了闪烁过程中产生的物种的性质，并研究了作为PQD尺寸函数的PL闪烁机制。此外，通过研究大多数显示器件工作的高光激发强度下的多激子动力学，评估了MAPbBr₃ PQD的实际适用性。超快瞬态吸收光谱有助于揭示与体积相关的俄歇复合率，通过比较与表面陷阱态和高能带态相关的早期跃迁进一步探索这一复合率。
