Codoping of Lead-Free Double Perovskites Promotes Near-Infrared Photoluminescence.

In the rapidly developing smart era, near-infrared luminescent materials have important applications in various fields that are closely related to people. Nag and co-workers provided a first codoping strategy to achieve efficient near-infrared photoluminescence in lead-free double perovskite materials. Through the introduction of Bi3+ ions, a new energy state is formed that leads to the absorption of lower-energy light. The excited state formed by this light absorption subsequently excites f-electrons of Er3+ or Yb3+ ions, and the relaxation of these f-electrons results in near-infrared photoluminescence. This may open a new chapter in the application of perovskites for infrared detection and human sensing.