Phase transition and rapid temperature response of lead-free perovskite Cs–Cu–I nanocrystals enabled by their size

Reducing the amount of Cs-oleate can reduce the size of Cs 3 Cu 2 I 5 lead-free perovskite nanocrystals from 22 to 10 nm. The as-obtained nanocrystals show a more uniform size distribution and a more rapid response to temperature change of only 15 s.