Stable and Efficient Red Perovskite Light-Emitting Diodes Based on Ca^(2+)-Doped CsPbI_(3) Nanocrystals

α-CsPbI3 nanocrystals(NCs)with poor stability prevent their wide applications in optoelectronic fields.Ca^(2+)(1.00Å)as a new B-site doping ion can successfully boost CsPbI3 NC performance with both improved phase stability and optoelectronic properties.With a Ca^(2+)/Pb^(2+)ratio of 0.40%,both phase and photoluminescence(PL)stability could be greatly enhanced.Facilitated by increased tolerance factor,the cubic phase of its solid film could be maintained after 58 days in ambient condition or 4 h accelerated aging process at 120℃.The PL stability of its solution could be preserved to 83%after 147 days in ambient condition.Even using UV light to accelerate aging,the T_(50) of PL could boost 1.8-folds as compared to CsPbI_(3) NCs.Because Ca^(2+) doping can dramatically decrease defect densities of films and reduce hole injection barriers,the red light-emitting diodes(LEDs)exhibited about triple enhancement for maximum the external quantum efficiency(EQE)up to 7.8%and 2.2 times enhancement for half-lifetime of LED up to 85 min.We believe it is promising to further explore high-quality CsPbI_(3) NC LEDs via a Ca^(2+)-doping strategy.