Unraveling the Interplay of Charge Transfer and Excited State Dynamics in MAPbBr₃/Bi₂Se₃ Heterostructures

The distinctive surface states of Bi 2 Se 3, recognized as topological insulators, have garnered considerable attention for their phenomenal electronic and optical characteristics. Heterostructures (HS) integrating Bi 2 Se 3 have emerged as viable prospects for a variety of applications despite hurdles such as attaining high-quality interfaces, complicated fabrication processes, and maximizing optoelectronic performance. The synergistic coupling of Bi 2 Se 3 and halide perovskite materials provides potential such as variable bandgaps and improved charge carrier mobility. In this work, we fabricated the HS of Bi 2 Se 3 with MAPbBr 3, with the aim of understanding changes in fundamental properties and excited state dynamics under different heterostructuring conditions. We observed the critical role of surface matching conditions in determining lattice compatibility between materials and influencing the crystallization of MAPbBr 3 precursor solutions. We demonstrate the occurrence of several phenomena in these heterostructures using transient absorption analysis. These include charge transfer, extended carrier recombination lifetimes, and bandgap renormalization. We also observe polaron formation, hot carrier cooling, and exciton–exciton annihilation. Additionally, inverse bremsstrahlung and excitonic interactions are identified. Moreover, the investigation of carrier temperature dependence indicates the participation of phonon bottleneck effects and Frohlich phonon emission. Because of their ability to achieve considerable charge transfer efficiencies resulting from strong electron–phonon coupling and excitonic interactions, we hypothesize that such heterostructures offer promise for effective photovoltaic and optoelectronic applications. Further exploration of the integration of other perovskite materials with Bi 2 Se 3 is crucial for unlocking their full potential in practical devices.