All Optically Switchable Active Photonics Based on the Halide Perovskite GST Platform

Halide perovskites are a class of semiconductors with strong direct interband transition and high mobility of charge carriers resulting in bright luminescence, which can be easily tuned chemically in a broad spectral range. Moreover, perovskites can be synthesized by means of simple wet chemistry approaches on arbitrary surfaces, opening new avenues for perovskites integration with a plethora of other functional materials. Here, this work reports on a versatile platform for reversible switching of halide perovskite's optical properties enabled by high-index phase-change materials (Ge-Sb-Te) serving as an active subnanolayer, which controls the perovskite film's behavior. Based on this approach, this work demonstrates micro-QR-coding and switchable bright emission, whose wavelength can be adjusted in the whole visible range.