Selective electron transport at CsPbI3(001)/TiO2(001) interfaces: Finite-temperature electronic structure insights

• A static structural model captures finite-temperature dynamics in CsPbI₃. • Band alignment at CsPbI₃/TiO₂ interfaces depends strongly on surface termination. • PbI₂-terminated CsPbI₃ enables efficient electron transport into TiO₂. • CsI termination suppresses electron injection across the interface. • Findings provide design rules for selective charge transport in perovskite solar cells. Accurate descriptions of the electronic structure of halide perovskites at finite temperatures require structural models that capture the dynamical tilting of BX 6 octahedra. Here, we demonstrate that a single static structure—constructed by combining the low-temperature γ-phase geometry with the cubic lattice of the α-phase—reproduces results obtained from time-averaged trajectories. Using this approach, we investigate how free surfaces and interfaces modify the electronic structure of lead-halide perovskites. Focusing on CsPbI 3 as a model halide perovskite interfaced with the prototypical electron transport layer TiO 2 , we make quantitative predictions of band offsets and band bending for the two possible CsPbI 3 (001) surface terminations, PbI 2 and CsI. Our results reveal that TiO 2 acts as an efficient electron transport layer only in the case of PbI 2 termination, highlighting the termination-dependent selectivity of charge transport at halide perovskite/TiO 2 interfaces.