Controlled Growth of Monocrystalline Organo‐Lead Halide Perovskite and Its Application in Photonic Devices

Organo‐lead halide perovskites (OHPs) have recently emerged as a new class of exceptional optoelectronic materials, which may find use in many applications, including solar cells, light emitting diodes, and photodetectors. More complex applications, such as lasers and electro‐optic modulators, require the use of monocrystalline perovskite materials to reach their ultimate performance levels. Conventional methods for forming single crystals of OHPs like methylammonium lead bromide (MAPbBr₃) afford limited control over the product morphology, rendering the assembly of defined microcavity nanostructures difficult. We overcame this by synthesizing for the first time (MA)[PbBr₃]⋅DMF ( 1 ), and demonstrating its facile transformation into monocrystalline MAPbBr₃ microplatelets. The MAPbBr₃ microplatelets were tailored into waveguide based photonic devices, of which an ultra‐low propagation loss of 0.04 dB μm⁻¹ for a propagation distance of 100 μm was demonstrated. An efficient active electro‐optical modulator (AEOM) consisting of a MAPbBr₃ non‐linear arc waveguide was demonstrated, exhibiting a 98.4 % PL intensity modulation with an external voltage of 45 V. This novel synthetic approach, as well as the demonstration of effective waveguiding, will pave the way for developing a wide range of photonic devices based on organo‐lead halide perovskites.