Dave Kashyap, Bao Zhen, Nakahara Satoshi, Ohara Keiichi, Masada Sojiro, Tahara Hirokazu, Kanemitsu Yoshihiko, Liu Ru-Shi
Department of Chemistry and Advanced Research Center of Green Materials Science and Technology, National Taiwan University, Taipei 106, Taiwan.
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Nanoscale. 2020 Feb 14;12(6):3820-3826. doi: 10.1039/c9nr09056h. Epub 2020 Jan 29.
Surface defects and synthesis methods play important roles in the photoluminescence quantum yield (PLQY), stability, and the device performance of lead halide perovskite quantum dots (PQDs). In this study, we report a quadruple-ligand (tri-n-octylphosphine, didodecyldimethylammonium bromide, tetraoctylammonium bromide, and oleic acid) assisted room-temperature method for synthesizing CsPbBr QDs (RT-CsPbBr) with an absolute PLQY of 83%. X-ray photoelectron spectroscopy confirms the high completeness of the Pb-Br octahedron through the absence of lead ions and presence of more bromide ions on the surface of RT-CsPbBr QDs. The exciton dynamics of RT-CsPbBr QDs is studied by using femtosecond transient absorption, time-resolved PL, and single-dot spectroscopy, which provide strong evidence of the suppression of trion formation compared with the hot injection-synthesized CsPbBr (HI-CsPbBr) QDs. The white light-emitting diode (LED) fabricated with RT-CsPbBr PQDs and a KSiF:Mn phosphor for backlight applications achieved a wide color gamut of 124% of the National Television System Committee (NTSC) standard.
表面缺陷和合成方法对卤化铅钙钛矿量子点（PQDs）的光致发光量子产率（PLQY）、稳定性及器件性能起着重要作用。在本研究中，我们报道了一种四元配体（三正辛基膦、二甲基二癸基溴化铵、四辛基溴化铵和油酸）辅助的室温合成法，用于制备绝对PLQY为83%的CsPbBr量子点（RT-CsPbBr）。X射线光电子能谱通过RT-CsPbBr量子点表面不存在铅离子且存在更多溴离子，证实了Pb-Br八面体的高完整性。利用飞秒瞬态吸收、时间分辨PL和单量子点光谱研究了RT-CsPbBr量子点的激子动力学，与热注入合成的CsPbBr（HI-CsPbBr）量子点相比，这些研究为抑制三重激子形成提供了有力证据。用RT-CsPbBr PQDs和用于背光应用的KSiF:Mn荧光粉制备的白光发光二极管（LED）实现了124%美国国家电视系统委员会（NTSC）标准的宽色域。
