Interfacial photophysics in perovskite–2D material heterostructures

Perovskite–2D material heterostructures have evolved from empirical interface engineering motifs to model systems for controlling interfacial photophysics in solution-processed optoelectronics. Graphene, MXenes, transition-metal dichalcogenides (TMDs), black phosphorus, and related layered materials can improve device operation through charge extraction, contact stabilization, recombination suppression, morphology control, or radiative-state management. However, these outcomes cannot be understood from the material identity perspective alone. This review organizes perovskite–2D material interfaces according to the interfacial variable they control and the photoexcited-state pathway they enable. Electrode-facing graphene and MXene contacts primarily regulate tunneling, work-function alignment, carrier extraction, and stability. Semiconducting perovskite/TMD heterostructures introduce finite-bandgap interfaces where selective transfer, interfacial coupling, and excitonic or valley-sensitive responses become important. Structure- and field-mediating interfaces act through growth control, strain release, grain-boundary carrier pathways, or local electrostatic fields rather than through uniform planar charge transfer. We then connect these archetypes to three interfacial photophysical regimes: extraction-dominated, loss-dominated, and coupling-sensitive. Particular emphasis is laid on spectroscopic readout, including time-resolved photoluminescence (TRPL), transient absorption, ultraviolet photoelectron spectroscopy (UPS)/Kelvin probe force microscopy (KPFM), photocurrent dynamics, and second harmonic generation (SHG) or time-resolved SHG, because similar observables can arise from different mechanisms. Finally, we discuss how these pathways determine solar-cell, photodetector, and emission- or gain-device performance as well as outline future directions toward cleaner, more programmable, and more diagnosable perovskite–2D material interfaces.