Large Cation Engineering in Organic Antimony Halides for Low-Loss Active Waveguide

Active waveguides have attracted growing attention as a basic component of miniaturized and integrated photonic devices. However, most optical waveguide materials suffer from severe self-absorption, which greatly increases the optical loss. Therefore, developing highly efficient red-emitting materials with large Stokes shift and negligible self-absorption is of great interest. Herein, this work proposes a strategy to achieve both large Stokes shifts and high photoluminescence quantum yield (PLQY) in organic metal halide via large cation engineering. Two zero-dimensional antimony(III) chlorides, (TMA)₂SbCl₅ and (TMAA)₂SbCl₅, are designed and synthesized by screening the ligands with different cationic volumes. Experimental and theoretical results reveal that the large cation can promote the self-trapped excitons emission and improve stability. Benefiting from the large Stokes shift (291 nm) and high PLQY (98.3%), the as-prepared (TMAA)₂SbCl₅ microplate exhibits efficient active waveguide with low loss coefficient of 6.07 × 10⁻³ dB µm⁻¹. This work not only develops a novel active waveguide material, but also provides insights into the role of organic cation, which will provide new inspiration for the exploitation of excellent luminescent metal halides and photonic devices. © 2023 Wiley-VCH GmbH.