Tailoring the electronic structure of perovskite materials on ultrafast timescales is expected to shed light on optimizing optoelectronic applications. However, the transient bandgap renormalization observed upon photoexcitation is commonly explained by many-body interactions of optically created electrons and holes, which shrink the original bandgap by a few tens of millielectronvolts with a sub-picosecond time constant, while the accompanying phonon-induced effect remains hitherto unexplored. Here we unravel a significant contribution of hot phonons in the photo-induced transient bandgap renormalization in MAPbBr3 single crystals, as evidenced by asymmetric spectral evolutions and transient reflection spectral shifts in the picosecond timescale. Moreover, we performed a spatiotemporal study upon optical excitation with time-resolved scanning electron microscopy and identified that the surface charge carrier diffusion and transient bandgap renormalization are strongly correlated in time. These findings highlight the need to re-evaluate current theories on photo-induced bandgap renormalization and provide a new approach for precisely controlling the optical and electronic properties of perovskite materials, enabling the design and fabrication of high-performance optoelectronic devices with exceptional efficiency and unique properties.
Bibliographical noteFunding Information:
This work was supported by the King Abdullah University of Science and Technology (KAUST). The authors thank S. Shikin and KAUST Solar Centre for the technical support. The authors also thank Y. Zhang, A. Dikhtiarenko, and KAUST Imaging and Characterization Core Laboratory for the temperature-dependent steady-state measurements.
© 2023 The Royal Society of Chemistry.
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Process Chemistry and Technology
- Electrical and Electronic Engineering