Electrically assisted amplified spontaneous emission in perovskite light-emitting diodes

Abstract

Metal halide perovskites have emerged as promising gain materials for thin-film laser diodes. However, achieving electrically excited amplified spontaneous emission (ASE) in perovskite light-emitting diodes (PeLEDs), a pre-condition for perovskite laser diodes, is hindered by the conflicting requirements of high conductivity and high net modal gain of the device stack. Here we develop a transparent PeLED architecture that combines low optical losses with excellent current-injection properties. Using 2.3 ns optical pulses at 77 K, we achieve ASE with a threshold of 9.1 μJ cm−2. Upon submicrosecond electrical excitation at 77 K of the same device, we achieve current densities above 3 kA cm−2 with irradiance values above 40 W cm−2. Notably, co-pumping the PeLED with optical pulses that are synchronized with the leading edge of an intense electrical pulse results in a reduction of the ASE threshold by 1.2 ± 0.2 μJ cm−2, showing that electrically injected carriers contribute to optical gain. Furthermore, to assess the feasibility of a perovskite semiconductor optical amplifier, we probe the PeLED with 1-μs-long optical excitation and observe continuous-wave ASE at a threshold of 3.8 kW cm−2. Finally, we show that such intense electrical pulses generate electroluminescence brightness levels close to half the irradiance produced by continuous-wave optical pumping at the ASE threshold. This work shows that perovskite semiconductor optical amplifiers and injection lasers are within reach using this type of transparent PeLED. Electrically injected charges can effectively contribute to optical gain in perovskite light-emitting diodes under optical and electrical co-excitation.