Sb3+-Doping Induced Self-Trapped Excitons and Ultrafast Carrier Dynamics in 0D Hybrid Indium Halides

Organic-inorganic metal halides (OIMH) doped with Sb 3+ often exhibit excellent optoelectronic properties, however, their photoluminescence (PL) mechanisms, especially after Sb 3+ doping, require a deeper understanding of their excited states and optical transitions. Through synergistic analysis of temperature-dependent PL and femtosecond transient absorption (fs-TA） spectroscopic study, the coexistence of dual polaronic states and their temperature-dependent transient bipolaronic state absorption processes in 0D Sb 3+ :(C 2 H 8 N) 4 InCl 7 system have been identified: (1) Sb 3+ -site polaron or self-trapped exciton(STE) emission originating from spin-allowed ( 3 P 1 → 1 S 0 ) and ( 1 P 1 → 1 S 0 ) in SbCl 6 octahedra) is favorably formed first, giving emission at 615 nm at room temperature; (2) In 3+ -Sb 3+ donor-acceptor pair (DAP) STE (In 3 P 1 → Sb 1 S 0 ) can be produced under 111.2 cm −1 Longitudinal Optical (LO) phonon assistance at 160 K and giving emission 700 nm at room temperature. Both polaronic states can collaborate to give the broad emission with a photoluminescence quantum yield (PLQY) of 98.4%. Though 0D structure, close energy span between Sb(III) and In(III) can cause such DAP behavior for Sb 3 ⁺ with 5s 2 electrons in the In-Cl matrix, this provides key insights into the radiation synergy effects with the host via short and long-range phonons. This model paves the way for developing novel high-performance luminescent materials for optoelectronic applications.