P‐9.2: High Performance Quasi‐2D Perovskite Cyan‐Blue Light‐Emitting Diodes by Using a Bifunctional Ligand

Despite substantial progress has been achieved in red/near‐infrared, green, and blue perovskite light‐emitting diodes (PeLEDs), studies on cyan emitting perovskites are still lacking. However, cyan‐emitting perovskite materials are of great importance and have many promising applications, especially for high‐quality lighting and light communication. Herein efficient cyan‐blue PeLEDs simultaneously achieving high luminance and high color stability are fabricated by using a bifunctional ligand, L‐Phenylalanine Methyl ester hydrochloride (L‐PMEH). It reveals the carboxyl and amine groups would heal charged defects via electrostatic interactions, and the neutral chlorine related defects can be reduced by the aromatic structures. The optimized cyan‐blue PeLEDs show a maximum external quantum efficiency (EQE) of 6.17% with an emission peak at 497 nm and a full width at half‐maximum of 21 nm as well as CIE coordinates of (0.09, 0.19). The obtained maximum luminance of 6347 cd m –2 is one of the highest values among the efficient and color‐stable cyan‐blue PeLEDs.