Ahn Jihoon, Ma Sunihl, Kim Ji-Young, Kyhm Jihoon, Yang Wooseok, Lim Jung Ah, Kotov Nicholas A, Moon Jooho
Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea.
Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
J Am Chem Soc. 2020 Mar 4;142(9):4206-4212. doi: 10.1021/jacs.9b11453. Epub 2020 Feb 21.
The effect of chemical-composition modification on the chiroptical property of chiral organic ammonium cation-containing organic inorganic hybrid perovskite (chiral OIHP) is investigated. Varying the mixing ratio of bromide and iodide anions in - or -CHCH(CH)NH)PbIBr modifies the band gap of chiral OIHP, leading to a shift of the circular dichroism (CD) signal from 495 to 474 nm. However, it is also found that an abrupt crystalline structure transition occurs, and the CD signal is turned off when iodide-determinant phases are transformed into the bromide-determinant phase. To obtain CD in the wavelength range where the bromide-determinant phase is supposed to exhibit chiroptical activity, that is, <474 nm, - or -CHCH(CH)NH with a larger spacer group can be adopted; thus, the CD signal can be further blue-shifted to ∼375 nm. Here, we show that chemical-composition modification of chiral OIHP affects the chiroptical properties of chiral OIHP in two ways: (1) tuning the wavelength of CD by modulating the excitonic band structure and (2) switching the CD on and off by inducing a crystalline-structure change. These properties can be utilized for structural engineering of high-performance chiroptical materials for spin-polarized light-emitting devices and polarization-based optoelectronics.
研究了化学成分改性对含手性有机铵阳离子的有机无机杂化钙钛矿（手性OIHP）手性光学性质的影响。改变-(CH₃)₂CHCH₂NH₃)PbI₂Br₁₋ₓ中溴化物和碘化物阴离子的混合比例会改变手性OIHP的带隙，导致圆二色性（CD）信号从495 nm移至474 nm。然而，还发现会发生突然的晶体结构转变，当碘化物主导相转变为溴化物主导相时，CD信号消失。为了在溴化物主导相预期表现出手性光学活性的波长范围内获得CD，即<474 nm，可以采用具有更大间隔基团的-(CH₃)₂CHCH₂NH₃⁺或-(CH₃)₃NH⁺；因此，CD信号可以进一步蓝移至~375 nm。在此，我们表明手性OIHP的化学成分改性以两种方式影响手性OIHP的手性光学性质：（1）通过调节激子能带结构来调整CD波长；（2）通过诱导晶体结构变化来开启和关闭CD。这些特性可用于自旋极化发光器件和基于偏振的光电子学的高性能手性光学材料的结构工程。
