Ultralow‐loss Optical Waveguides through Balancing Deep‐Blue TADF and Orange Room Temperature Phosphorescence in Hybrid Antimony Halide Microstructures

Abstract Harnessing the potential of thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) is crucial for developing light‐emitting diodes (LEDs), lasers, sensors, and many others. However, effective strategies in this domain are still relatively scarce. This study presents a new approach to achieving highly efficient deep‐blue TADF (with a PLQY of 25 %) and low‐energy orange RTP (with a PLQY of 90 %) through the fabrication of lead‐free hybrid halides. This new class of monomeric and dimeric 0D antimony halides can be facilely synthesized using a bottom‐up solution process, requiring only a few seconds to minutes, which offer exceptional stability and nontoxicity. By leveraging the highly adaptable molecular arrangement and crystal packing modes, the hybrid antimony halides demonstrate the ability to self‐assemble into regular 1D microrod and 2D microplate morphologies. This self‐assembly is facilitated by multiple non‐covalent interactions between the inorganic cores and organic shells. Notably, these microstructures exhibit outstanding polarized luminescence and function as low‐dimensional optical waveguides with remarkably low optical‐loss coefficients. Therefore, this work not only presents a pioneering demonstration of deep‐blue TADF in hybrid antimony halides, but also introduces 1D and 2D micro/nanostructures that hold promising potential for applications in white LEDs and low‐dimensional photonic systems.