  While metal-halide perovskites have recently revolutionized research in
optoelectronics through a unique combination of performance and synthetic
simplicity, their low-dimensional counterparts can further expand the field
with hitherto unknown and practically useful optical functionalities. In this
context, we present the strong temperature dependence of the photoluminescence
(PL) lifetime of low-dimensional, perovskite-like tin-halides, and apply this
property to thermal imaging with a high precision of 0.05 {\deg}C. The PL
lifetimes are governed by the heat-assisted de-trapping of self-trapped
excitons, and their values can be varied over several orders of magnitude by
adjusting the temperature (up to 20 ns {\deg}C-1). Typically, this sensitive
range spans up to one hundred centigrade, and it is both compound-specific and
shown to be compositionally and structurally tunable from -100 to 110 {\deg} C
going from [C(NH2)3]2SnBr4 to Cs4SnBr6 and (C4N2H14I)4SnI6. Finally, through
the innovative implementation of cost-effective hardware for fluorescence
lifetime imaging (FLI), based on time-of-flight (ToF) technology, these novel
thermoluminophores have been used to record thermographic videos with high
spatial and thermal resolution.
