具有明亮双色发射的无铅直接带隙双钙钛矿纳米晶体
Lead-Free Direct Band Gap Double-Perovskite Nanocrystals with Bright Dual-Color Emission.
作者信息
Yang Bin, Mao Xin, Hong Feng, Meng Weiwei, Tang Yuxuan, Xia Xusheng, Yang Songqiu, Deng Weiqiao, Han Keli
机构信息
University of the Chinese Academy of Sciences , Beijing 100049 , P.R. China.
School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, and Institute for Advanced Studies , Wuhan University , Wuhan 430072 , China.
出版信息
J Am Chem Soc. 2018 Dec 12;140(49):17001-17006. doi: 10.1021/jacs.8b07424. Epub 2018 Dec 3.
Lead-free double-perovskite nanocrystals (NCs), that is, CsAgIn BiCl ( x = 0, 0.25, 0.5, 0.75, and 0.9), that can be tuned from indirect band gap ( x = 0, 0.25, and 0.5) to direct band gap ( x = 0.75 and 0.9) are designed. Direct band gap NCs exhibit 3 times greater absorption cross section, lower sub-band gap trap states, and >5 times photoluminescence quantum efficiency (PLQE) compared to those observed for indirect band gap NCs (CsAgBiCl). A PLQE of 36.6% for direct band gap NCs is comparable to those observed for lead perovskite NCs in the violet region. Besides the band edge violet emission, the direct band gap NCs exhibit bright orange (570 nm) emission. Density functional theory calculations suggesting forbidden transition is responsible for the orange emission, which is supported by time-resolved PL and PL excitation spectra. The successful design of lead-free direct band gap perovskite NCs with superior optical properties opens the door for high-performance lead-free perovskite optoelectronic devices.
设计出了无铅双钙钛矿纳米晶体（NCs），即CsAgInBiCl₆（x = 0、0.25、0.5、0.75和0.9），其能带隙可从间接带隙（x = 0、0.25和0.5）调谐为直接带隙（x = 0.75和0.9）。与间接带隙纳米晶体（CsAgBiCl₆）相比，直接带隙纳米晶体的吸收截面大3倍，亚带隙陷阱态更低，光致发光量子效率（PLQE）高出5倍以上。直接带隙纳米晶体36.6%的PLQE与在紫色区域观察到的铅钙钛矿纳米晶体相当。除了带边紫色发射外，直接带隙纳米晶体还表现出明亮的橙色（570 nm）发射。密度泛函理论计算表明禁戒跃迁是橙色发射的原因，时间分辨PL和PL激发光谱也证实了这一点。具有优异光学性能的无铅直接带隙钙钛矿纳米晶体的成功设计为高性能无铅钙钛矿光电器件打开了大门。
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