Thermal Properties of Polymer Hole-Transport Layers Influence the Efficiency Roll-off and Stability of Perovskite Light-Emitting Diodes
Lianfeng Zhao, Daniel D. Astridge, William B. Gunnarsson, Zhaojian Xu, Jisu Hong, J.L. Scott, Sara Kacmoli, Khaled Al Kurdi, Stephen Barlow, Seth R. Marder, Claire Gmachl, Alan Sellinger, Barry P. Rand
Abstract
While the performance of metal halide perovskite light-emitting diodes (PeLEDs) has rapidly improved in recent years, their stability remains a bottleneck to commercial realization. Here, we show that the thermal stability of polymer hole-transport layers (HTLs) used in PeLEDs represents an important factor influencing the external quantum efficiency (EQE) roll-off and device lifetime. We demonstrate a reduced EQE roll-off, a higher breakdown current density of approximately 6 A cm –2, a maximum radiance of 760 W sr –1 m –2, and a longer device lifetime for PeLEDs using polymer HTLs with high glass-transition temperatures. Furthermore, for devices driven by nanosecond electrical pulses, a record high radiance of 1.23 MW sr –1 m –2 and an EQE of approximately 1.92% at 14.6 kA cm –2 are achieved. Thermally stable polymer HTLs enable stable operation of PeLEDs that can sustain more than 11.7 million electrical pulses at 1 kA cm –2 before device failure.