Dual‐Mode Optical Thermometry and Plant‐Growth Lighting Enabled by Sb3+‐Doped Organic‐Metal Halide Thin Films

Abstract

The integration of optical environmental sensing with plant photophysiological regulation into a single‐material platform remains a key challenge for smart agriculture. Here, we report a flexible luminescent composite film based on Sb3+‐doped (C18H15S)2InCl5 in a polydimethylsiloxane matrix, which combines optical thermometry and tailored plant‐growth lighting. Multidimensional analyses using Raman spectroscopy and steady‐state/time‐resolved photoluminescence (PL) elucidate the key role of electron‐phonon coupling in energy‐level modulation and radiative transitions. The emission shows strong excitation‐wavelength dependence. Under 360 nm excitation, the film exhibits a pronounced thermochromic shift from red (80 K) to yellow (480 K), enabling temperature readout through emission‐peak shifts with a maximum relative sensitivity (Sr) of 0.72% K−1 and supporting visual temperature monitoring for cold‐chain logistics. Under 320 nm excitation, simultaneously activated singlet and triplet dual emissions generate a self‐calibrated ratiometric optical thermometer with a maximum Sr of 3.92% K−1. Benefiting from its high PL quantum yield and broadband emission matching chlorophyll absorption, orange‐red and white LEDs are fabricated. Plant‐cultivation tests on gotu kola, garlic sprouts, and Chinese‐cabbage seedlings show enhanced growth and chlorophyll accumulation under these tailored light sources. The material presents a flexible optical material that integrates temperature sensing, self‐calibrated thermometry, and plant‐growth photoregulation, providing a materials strategy for smart agriculture.