Dimethylamine metal halides for high-sensitivity fluorescence lifetime thermometry

Abstract

Organic–inorganic metal halides (OIMHs) are widely recognized for their varied structures, tunable bandgaps, and outstanding efficiency in optoelectronic applications. Meanwhile, their temperature-dependent luminescence lifetime supports advanced functionalities such as temperature sensing and thermal imaging. In this study, two new zero-dimensional (0D) lead-free OIMHs with dimethylamine were synthesized: DMA₄InBr₇ and DMA₃SbBr₆. Notably, DMA₄InBr₇ exhibits bright, broad-band orange emission with a full width at half maximum of 199 nm, a Stokes shift of 298 nm, and a photoluminescence quantum yield as high as 50.4%. Sb³⁺ doping significantly enhanced the absorption of this In bromide, increasing its external quantum efficiency from 5.8% to 22.4%. Additionally, DMA₄InBr₇ : 1%Sb exhibited excellent air stability and its fluorescence lifetime was highly sensitive to temperature variations, with a sensitivity of 7.0% K⁻¹ at 340 K. This work suggests that 0D Sb-doped OIMHs are promising systems for applications in fluorescence thermometry.