Direct Laser Writing of delta- to alpha-Phase Transformation in Formamidinium Lead Iodide

摘要

Organolead halide perovskites are increasingly considered for applications well beyond photovoltaics, for example, as the active regions within photonic devices. Herein, we report the direct laser writing (DLW: 458 nm cw-laser) of the formamidinium lead iodide (FAPbI(3)) yellow delta-phase into its high-temperature luminescent black alpha-phase, a remarkably easy and scalable approach that takes advantage of the material's susceptibility to transition under ambient conditions. Through the DLW of alpha-FAPbI(3) tracks on delta-FAPbI(3) single-crystal surfaces, the controlled and rapid microfabrication of highly luminescent structures exhibiting long-term phase stability is detailed, offering an avenue toward the prototyping of complex perovskite-based optical devices. The dynamics and kinetics of laser-induced delta- to alpha-phase transformations are investigated in situ by Raman microprobe analysis, as a function of irradiation power, time, temperature, and atmospheric conditions, revealing an interesting connection between oxygen intercalation at the surface and the delta- to alpha-phase transformation dynamics, an insight that will find application within the wider context of FAPbI(3) thermal phase relations.