Color-pure red light-emitting diodes based on two-dimensional lead-free perovskites

Efficient lead-free perovskite light-emitting diodes with color coordinates that fulfill Rec. 2100 requirements are demonstrated. It remains a central challenge to the information display community to develop red light-emitting diodes (LEDs) that meet demanding color coordinate requirements for wide color gamut displays. Here, we report high-efficiency, lead-free (PEA) 2 SnI 4 perovskite LEDs (PeLEDs) with color coordinates (0.708, 0.292) that fulfill the Rec. 2100 specification for red emitters. Using valeric acid (VA)—which we show to be strongly coordinated to Sn 2+ —we slow the crystallization rate of the perovskite, improving the film morphology. The incorporation of VA also protects tin from undesired oxidation during the film-forming process. The improved films and the reduced Sn 4+ content enable PeLEDs with an external quantum efficiency of 5% and an operating half-life exceeding 15 hours at an initial brightness of 20 cd/m 2 . This work illustrates the potential of Cd- and Pb-free PeLEDs for display technology.