有序-无序诱导AgBiS_(2)可见-红外光响应调变机制

Optical Response Modulation of AgBiS_(2)Through Order-Disordered Transition

理想的红外光电材料可以在整个红外区(0.01~1.24 eV)产生红外光响应信号。本文结合特殊准无序结构(SQS)模型和第一性原理计算,研究了AgBiS_(2)的有序与无序结构的光电性质,预测了其有序-无序结构红外光响应的能量区间。计算结果表明,通过改变Ag和Bi占据位置的无序度,可以调控AgBiS_(2)的光学带隙,令其在0.33~1.46 eV范围内连续可调,从而实现大部分中红外、近红外区的光电响应。每分子完全有序和完全无序AgBiS_(2)之间的相转变只需0.11eV·(f.u.)^(-1),即仅通过控制合成温度,就可以精确调控AgBiS_(2)的带隙,从而进一步控制其在可见-红外区的响应范围。

An ideal infrared photoelectric material was expected to have a narrow band gap ranging of 0.01~1.24 eV,which covering the entire infrared region.In this paper,we proposed to design a stable infrared photoelectric semiconductor AgBiS_(2)by cation disorder.Adopting the quasi-random structures(SQS)combined with the first-principles calculations,the band gaps of ordered and disordered AgBiS_(2)were estimated.The calculated results showed that the optical band gap of AgBiS_(2)could be tuned continuously in the range of 0.33~1.46eV,achieving light response in the full near-infared and part of mid-infared region.The phase transition between fully ordered and fully disordered AgBiS_(2)required only 0.11eV/f.u..Therefore,we proposed that the band gap,i.e.the light-response region of AgBiS_(2)could be precisely adjusted by controlling the synthetic temperature.