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 , Cs 3 Cu 2 I 5 , is synthesized and applied for temperature sensing. A composite thin film combining Cs 3 Cu 2 I 5 with polymethyl methacrylate (PMMA) is developed for optical temperature sensing under different environmental conditions. The Cs 3 Cu 2 I 5 -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 °C to 80 °C with a temperature sensitivity up to 2.3% K −1 . The sensing performance and stability of the Cs 3 Cu 2 I 5 -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.