Improved current-efficiency of quasi-2D multi-cation perovskite light-emitting diodes: the effect of Cs and K
Multiple cation-substitution is an effective method to improve the stability of organic-inorganic hybrid perovskite thin-films. Here, we apply this approach to quasi two-dimensional (quasi-2D) perovskite materials, and investigate the effect of Cs and K doping on the performance of quasi-2D perovskite LEDs (PeLEDs). It is found that Cs significantly reduces the efficiency roll-off of quasi-2D PLEDs at high current-density, which leads to a high current-efficiency (CE) - even at an operation current-density as high as 1000mA/cm2. In addition, the incorporation of a small amount of K further increases the device quantum-efficiency thanks to its passivation effect. As a result, our green PeLED, which is based on a multi-cation quasi-2D perovskite, reaches a brightness of 45600cd/m2, and a maximum CE of 22.5cd/A. The approach introduced in this work has a great potential to enhance the performance of quasi-2D perovskite light-emitting diodes.