Manipulating Superfluorescence through Substrate Modifications in Quasi-2D Perovskite Thin Films

Student’s name: Nathaniel Tomas Home Institution: University of Minnesota Twin Cities NNCI Site: RTNN @ NC State University REU Principal Investigator: Franky So REU Mentor: Jingshan Chai Abstract: Superfluorescence (SF) has historically been observed under extremely strict conditions. Polycrystalline perovskite thin films are a promising platform for optoelectronics and potential room-temperature SF emission applications. However, these films are highly sensitive to different processing conditions, such as compositional factors, substrate effects, and processing environments. These processing conditions can significantly affect film quality which greatly influences carrier recombination and transport, affecting SF behavior. This study examines the impact of processing conditions on room-temperature SF in lead halide hybrid perovskites. We observed poor surface coverage in CsPbBr3 thin films compared to (PEABr)0.4CsPbBr3 films when fabricated without ultraviolet ozone (UVO) treatment on the substrate. To further investigate this phenomenon, we studied the effects of UVO treatment on the quality of (PEABr)0.4CsPbBr3 thin films. Increasing UVO treatment time not only enhances the hydrophilicity of the hydrophobic glass substrate but also leads to changes in the distribution of low-dimensional phases. These changes potentially influence the material's SF performance. We propose these changes result from changing chemical interactions between the substrate surface and the bulky organic cation in the perovskite due to varying UVO exposure time. Understanding the effects of processing conditions on a material’s ability to emit SF is crucial for guiding the development of SF-emitting materials.