Controlled synthesis of highly stable lead-free bismuth halide perovskite nanocrystals : tructures and photophysics

Summary, in English

Recently, cesium bismuth halide perovskites have emerged as potential substitutes to their counterparts, cesium lead halide perovskites, owing to their low toxicity. However, the photophysics of cesium-bismuth halides nanocrystals (NCs) have not yet been fully rationalized because their structures remain highly debated. The ultraviolet-visible (UV-vis) absorption along with other photophysical properties such as the nature and lifetime of the excited states vary considerably across the previous reports. Here, we successfully synthesize pure Cs₃BiBr₆ and Cs₃Bi₂Br₉ NCs via a modified hot-injection method, where the structure can be easily controlled by tuning the reaction temperature. The UV-vis absorption spectrum of the pure Cs₃Bi₂Br₉ NCs features two characteristic peaks originating from the absorption of the first exciton and second exciton, respectively, which ultimately clarifies the debate in the previous reports. Using femtosecond transient absorption spectroscopy, we systematically investigate the excited state dynamics of the Cs₃Bi₂Br₉ NCs and reveal that the photoexcited carriers undergo a self-trapping process within 3 ps after excitation. More intriguingly, the Cs₃Bi₂Br₉ NCs prepared by this method show much better photostability than those prepared by the ligand-assisted reprecipitation process. Photodetectors based on these Cs₃Bi₂Br₉ NCs show a sensitive light response, demonstrating the definite potential for breakthrough optoelectronic applications. [Figure not available: see fulltext.].

• Author: Huifang Geng; Zhuanzhuan Huang; Huaxiu Geng; Siyu Liu; Maria A. Naumova; Raffaele Salvia; Siqi Chen; Junli Wei; Lifu Zhang; Xianshao Zou; Weihua Lin; Xinyi Cai; Mingjian Yuan; Zhenpeng Hu; Xi Shen; Richeng Yu; Kaibo Zheng; Sophie E. Canton; Xuewen Fu
• Department/s: LTH Profile Area: Nanoscience and Semiconductor Technology; Chemical Physics; NanoLund: Centre for Nanoscience; LTH Profile Area: Photon Science and Technology
• Publishing year: 2023
• Language: English
• Pages: 2079-2089
• Publication/Series: SCIENCE CHINA Materials
• Volume: 66
• Issue: 5
• Links: http://dx.doi.org/10.1007/s40843-022-2299-6
• Document type: Journal article
• Publisher: Science China Press
• Topic: Physical Chemistry (including Surface- and Colloid Chemistry)
• Keywords: bismuth perovskites; hot injection; lead-free perovskites; nanocrystals; photostability
• Status: Published
• ISBN/ISSN/Other: ISSN: 2095-8226