Controlling of precursor micelle size by ternary co-spacer cations for efficient pure red quasi-2D PeLEDs with recommendation 2020 color coordinates

Abstract

Quasi-two-dimensional (quasi-2D) perovskites have emerged as one of the most promising luminescent materials owing to their outstanding optoelectronic properties and facile solution processability. However, high-performance pure red quasi-2D perovskite light-emitting diodes (PeLEDs) still remain a great challenge due to wide phase distribution and inefficient quantum well energy transfer. Here, we develop a ternary co-spacer cations system to vary the micelle size of the precursor solution and to modulate the phase distribution in film using phenylbutyl-ammonium (PBA+) as the third spacer cation, which has stronger binding energy with lead-halide octahedron. By virtue of its additional defect passivation effect, the resulting device displays a champion maximum external quantum efficiency (EQE) of 15.7 % with an electroluminescent peak at 631 nm and Commission Internationale de l’Éclairage (CIE) coordinates of (0.709, 0.290) as well as excellent spectral stability. This work provides useful guidance for perovskite phase modulation and the development of highly efficient pure-red PeLEDs.