Excimer Formation in the Non‐Van‐Der‐Waals 2D Semiconductor Bi2O2Se. Issue 35 (24th July 2022)

• Record Type: Journal Article
• Authors: Yu, Junhong; Han, Yadong; Zhang, Hang; Ding, Xiang; Qiao, Liang; Hu, Jianbo
• Is Part Of: Advanced materials. Volume 34:Issue 35(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-07-24
• Subjects: 2D materials -- bismuth oxyselenide -- excimers -- transient absorption -- ultrafast spectroscopy; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202204227
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: The layered semiconductor Bi2 O2 Se is a promising new‐type 2D material that holds layered structure via electrostatic forces instead of van der Waals (vdW) attractions. Aside from the huge success in device performance, the non‐vdW nature in Bi2 O2 Se with a built‐in interlayer electric field has also provided an appealing platform for investigating unique photoexcited carrier dynamics. Here, experimental evidence for the observation of excimers in multilayer Bi2 O2 Se nanosheets via transient absorption spectroscopy is presented. It is found that the excimer formation is the primary decay pathway of photoexcited excitons and three‐stage excimer dynamics with corresponding time scales are established. Excitation‐fluence‐dependent excimer dynamics further suggest that the excimer is diffusive and its formation can be simply described as excitons relaxed to an excimer geometry. This work indicates the outstanding promise of unique excitonic processes in Bi2 O2 Se, which may motivate novel device designs. Abstract : Excimer formation is unambiguously demonstrated in non‐van der Waals 2D semiconductor Bi2 O2 Se via transient absorption spectroscopy. The excimer in Bi2 O2 Se nanosheets is diffusive and its formation can be described as excitons relax to an excimer geometry driven by the ultrafast photoscreening of the intrinsic built‐in dipolar electric field.