Influence of surface passivation on perovskite CsPbBr1.2I1.8 quantum dots and application of high purity red light-emitting diodes

•TOPO and Pb(NO3)2 are employed to improve the quality and passivation of CsPbBr1.2I1.8 films.•Co-doped TOPO and Pb(NO3)2 can improve the performance of the LEDs. In this work, trioctylphosphine oxide (TOPO) ligand is employed to improve the quality of CsPbBr1.2I1.8 quantum dots (QDs) films. Lead nitrate (Pb(NO3)2) is also used to passivate the surface of the films. The study of ligand and surface passivation on the luminous efficiency of red light-emitting diode (LED) is discussed. The CsPbBr1.2I1.8 QDs films co-doped with TOPO and Pb(NO3)2 can effectively improve the performance of the CsPbBr1.2I1.8 QDs LEDs due to reduction of non-radiation recombination of the carriers and smooth morphology in the active layer, thus improving the injection and transportation capabilities of carriers. As a result, the highest luminosity and current efficiency are 502.7 cd/m2 and 0.175 cd/A, respectively.