Dr. Chunyun Wang
Tsinghua-Berkley Shenzhen Institute at Tsinghua University, China

Speech Title: Single-phase white-emitting lead-free inorganic perovskites for white LEDs

Abstract: White LEDs consisting of a single-phase white emitting luminescent material exhibit better color stability, lower costs and easier device fabrication, as compared to phosphor converted white LEDs containing a combination of red, green and blue emitting phosphors. As a single-phase white-emitting material, the halide perovskites have shown outstanding emission properties needed for white LED application. However, these materials often contain poisonous lead and relatively low chemical and thermal stability. Novel lead-free white-emitting perovskites are therefore urgently needed, and this work is therefore aimed at developing novel non-toxic, inorganic, white-emitting perovskites for LED applications.

Here, I will present a white-emitting double perovskite phosphor, in which the toxic lead has been replaced by more environmentally friendly indium and silver. The synthesis of both nano- and micron-sized perovskite particles will be described, as well as their structure and morphology. In addition, the opto-electronic properties of the novel perovskites are studied in detail, focusing on emission properties, quantum efficiency and thermal stability. To improve the optical properties of the perovskite phosphor, the perovskites have been doped with lanthanide and transition metal ions. The effect of the dopants on the luminescence properties is discussed. Finally, LED devices have been made to test the performance of the novel materials in real devices.