Zhang Yaru, Song Yilong, Lu Yuan, Zhang Zhuang, Wang Yang, Yang Yang, Dong Qingfeng, Yu Yi, Qin Peng, Huang Fuqiang
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Science, Beijing, 100049, China.
Small. 2022 Jun;18(24):e2201943. doi: 10.1002/smll.202201943. Epub 2022 May 16.
Lead-free Cs AgBiBr double perovskite is considered to be a promising alternative to the traditional lead-based analogues due to its long carrier lifetime, high structural stability, and non-toxicity. However, the large band gap limits its absorption of visible light, which is not conducive to further optoelectronic applications. Herein, a thermochromic strategy is reported to decrease the band gap of Cs AgBiBr by approximately 0.36 eV, obtaining the smallest reported band gap of 1.69 eV under ambient conditions. The experimental data indicate that after annealing the Cs AgBiBr single crystals at 400 °C, the silver (Ag) and bismuth (Bi) atoms occupy the B-site in a random way and form a partially disordered configuration. The formation of the antisite defects broadens the band edges and decreases the band gap. This work offers new insights into the preparation of narrow band gap lead-free double perovskites, and a deep understanding of their structural and electronic properties for further development in photoelectric devices.
无铅CsAgBiBr双钙钛矿因其长载流子寿命、高结构稳定性和无毒特性，被认为是传统铅基类似物的一种有前途的替代品。然而，较大的带隙限制了其对可见光的吸收，不利于进一步的光电子应用。在此，报道了一种热致变色策略，可将CsAgBiBr的带隙降低约0.36 eV，在环境条件下获得了报道中最小的1.69 eV带隙。实验数据表明，在400°C下对CsAgBiBr单晶进行退火后，银（Ag）和铋（Bi）原子以随机方式占据B位并形成部分无序构型。反位缺陷的形成拓宽了带边并减小了带隙。这项工作为窄带隙无铅双钙钛矿的制备提供了新的见解，并为深入了解其结构和电子特性以用于光电器件的进一步发展提供了帮助。
