Effect of the hole transport layer on the performance of sky-blue Dion-Jacobson perovskite light-emitting diodes

We investigated the performance of sky-blue quasi-2D Dion-Jacobson perovskite light-emitting diodes as a function of perovskite composition and device architecture. Perovskite composition optimization is needed in order to optimize the film structure to achieve a compromise between efficient funneling and a consequent red shift of the emission, achieving emission in the blue spectral range. Composition optimization was achieved by adjusting the ratio of spacer cations methylenediammonium (MDA) and decanediammonium (DDA) and 3D perovskite CsPbBr3, to achieve films with optimal composition for sky-blue emission. In addition to the perovskite composition, the choice of the hole transport layer (HTL) had a significant effect on device efficiency. Significant enhancement in the efficiency from 1.8% (control device with a self-assembled monolayer HTL) to 4.1% (optimized HTL structure) is achieved by inserting diphenyl-4-triphenylsilylphenyl phosphine oxide (TSPO1) between the HTL layers and the perovskite. This results in an improved balance of electron and hole injection, as well as passivation of defects in the perovskite, which is responsible for the observed improvements in device performance. Increased efficiency of sky-blue LEDs based on Dion-Jacobson perovskite emitters is achieved through the optimization of the hole transport layer-perovskite interface.