In polar crystals, excited electron-hole pairs can be captured by the deformation
potential field created by lattice distortion upon photoexcitation, due to strong electron-phonon
interactions, thereby forming self-trapped excitons. Metal halide perovskites are semiconductors that display efficient self-trapped exciton luminescence in various systems due to their
ionic crystal nature with strong electron-phonon interactions and a deformable lattice. Consequently, they are considered ideal for creating high-quality white light sources. However, the
understanding of the self-trapped exciton luminescence mechanism in metal halide perovskites
is still relatively scarce and lags far behind the development of devices. To this end, this paper
summarizes the recent research progress on the formation conditions, formation mechanism
and related excited state dynamics of self-trapped excitons in metal halide perovskites semiconductors from the perspective of the fundamental physics of self-trapped excitons, and gives
an outlook on the future research based on the self-trapped exciton mechanism in this system,
so as to provide a clearer physical image for the study of self-trapped excitons in this system
