Sterically Hindered Heterometallic Polyhedral Pairs in Halide Perovskite Derivative Enable Energy‐Transfer‐Enhanced Singlet Self‐Trapped Excitons for Full‐Spectrum White Light Emission

ABSTRACT Halide perovskite derivatives with broad‐spectrum emission have emerged as a promising candidate for next‐generation single‐source phosphor. However, most of the halide perovskite derivatives tend to emit warm‐yellow emission and often lack long‐life high‐energy emission. In this study, a novel strategy based on “sterically hindered heterometallic polyhedral pairs” enables energy‐transfer‐enhanced singlet self‐trapped exciton ( 1 STE) emission for realizing white emission. Through Sb 3+ doping, [SbCl 5 ] 2− ‐[MnCl 4 ] 2− polyhedral pairs effectively promote energy transfer from [MnCl 4 ] 2− to [SbCl 5 ] 2− , resulting in a 3.6‐fold increase in intensity of blue emission originating from 1 STEs of Sb 3+ , and a prolonged lifetime from nanoseconds to microseconds by three orders of magnitude. The CIE coordinate of (0.322, 0.377) closely matches standard white illumination. Mechanism studies reveal that the inter‐polyhedral distance, overlap of density of states, and suitable energy band structures collectively facilitate energy transfer. Moreover, the white emissive halide perovskite derivative is successfully applied in a prototype white LED device, highlighting its potential for solid‐state lighting. This work not only presents an effective structural design principle to realize white emission but also provides a new pathway to enhance the emission of singlet excitons, paving the way for development of high‐performance lighting materials.