Synthesis, Optical Properties, and Exciton Dynamics of Organolead Bromide Perovskite Nanocrystals

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• 作者：Binbin Luo ; Ying-Chih Pu ; Yi Yang ; Sarah A. Lindley ; Ghada Abdelmageed ; Hoda Ashry ; Yat Li ; Xueming Li ; Jin Z. Zhang
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：November 25, 2015
• 年：2015
• 卷：119
• 期：47
• 页码：26672-26682
• 全文大小：660K
• ISSN：1932-7455

文摘

Organolead bromide CH₃NH₃PbBr₃ perovskite nanocrystals (PNCs) with green photoluminescence (PL) have been synthesized using two different aliphatic ammonium capping ligands, octylammonium bromide (OABr) and octadecylammonium bromide (ODABr), resulting in PNC鈥揙ABr and PNC鈥揙DABr, respectively. Structural studies by X-ray diffraction (XRD) and transmission electron microscopy (TEM) determined that the PNCs exhibit cubic phase crystal structure with average particle size dependent on capping ligand (3.9 卤 1.0 nm for PNC鈥揙ABr and 6.5 卤 1.4 nm for PNC鈥揙DABr). The exciton dynamics of PNCs were investigated using femtosecond transient absorption (TA) techniques and singular value decomposition global fitting (SVD-GF), which revealed nonradiative recombination on the picosecond time scale mediated by surface trap states for both types of PNCs. The PL lifetime of the PNCs was measured by time-resolved photoluminescence (TRPL) spectroscopy and fit with integrated SVD-GF to determine the radiative as well as nonradiative lifetimes on the nanosecond time scale. Finally, a simple model is proposed to explain the optical and dynamic properties of the PNCs with emphasis on major exciton relaxation or electron鈥揾ole recombination processes. The results indicate that the use of capping ligand OABr resulted in PNCs with a high PL quantum yield (QY) of 鈭?0% (vs fluorescein, 95%), which have interesting optical properties and are promising for potential applications including photovoltaics, detectors, and light-emitting diodes (LEDs).