Highly stable luminescence temperature sensing based on eco-friendly lead-free cesium copper iodine perovskites

In this study, a kind of lead-free Cu(I) halide perovskites, Cs3Cu2I5, is synthesized and applied for temperature sensing. A composite thin film combining Cs3Cu2I5 with polymethyl methacrylate (PMMA) is developed for optical temperature sensing under different environmental conditions. The Cs3Cu2I5-PMMA films immersed in aqueous solutions exhibit stable sensing ability for at least 24 h, and show fully reversible sensing responses for the temperature change in the range from 30 degrees C to 80 degrees C with a temperature sensitivity up to 2.3% K-1. The sensing performance and stability of the Cs3Cu2I5-PMMA film show that it can be a type of temperature sensing materials with great potential. This work opens up a new use of lead-free copper-based halide perovskites and provides a new temperature sensing material.