Direct preparation of PEA2PbBr4 nanoplates with electron-irradiation-induced optical evolution

Abstract

Two-dimensional (2D) Ruddlesden-Popper (RP) phase perovskites, characterized by their soft lattice and high sensitivity to external stimuli, provide an excellent framework for exploring the dynamic evolution of crystal structure and optoelectronic properties. However, existing synthesis methods for high-quality RP-phase micro-nanoscale single crystals perovskite still face challenges in simultaneously achieving regular morphology and facile transferability. Here, we report a facile spatial confinement strategy that enables precise control over nucleation and growth kinetics of RP-phase perovskites, leading to the direct synthesis of uniform and well-defined PEA2PbBr4 nanoplates. The emission of as-synthesized nanoplates can be substantially modified by electron-beam irradiation. It is observed that upon exposure to e-beam irradiation at 30 keV, the photoluminescence (PL) of PEA2PbBr4 nanoplates undergoes a pronounced transformation from narrowband blue emission to broadband yellow emission spanning 400-750 nm. This emission evolution is attributed to electron-irradiation-induced lattice distortion, which promoted the formation of self-trapped excitons (STEs) and subsequently dominated radiative recombination. Based on regularly shaped nanoplates, PEA2PbBr4-PEA2Pb(Br-I)4 heterojunctions were constructed via vapor-phase anion-exchange. Optoelectronic devices incorporated with PEA2PbBr4 nanoplates were fabricated, exhibiting promising photodetection performance with responsivity of 1.44 A·W-1 and detectivity of 3.82 × 1012 Jones. This work not only provides a practical route for the direct synthesis of regularly shaped RP-phase nanoplates and their subsequent device integration, but also offers complementary insights into the interplay between lattice distortion and STE formation in layered perovskites.