Active area dependence of optoelectronic characteristics of perovskite LEDs

Abstract

Organometallic halide perovskites are non-epitaxial low-temperature semiconductors that show great promise in light-emission applications due to their favorable optoelectronic properties. Though high external quantum efficiencies exceeding 20% have been shown for perovskite LEDs, this is usually achieved at low current densities, and hence corresponds to low brightness. To reach high brightness, it is important to make strides in stability and quantum efficiency at high current density. In this work, we scale the active area of methylammonium lead iodide perovskite LEDs from 1000 μm in diameter down to tens of microns dimensions, relevant for emissive displays and laser devices that require high brightness. We systematically examine active-area-dependent perovskite LED performance from mA cm⁻² up to kA cm⁻² current density regimes by means of quasi-DC, DC, and sub-μs pulsed driving. For perovskite LEDs with diameters of 50 μm on glass substrates, we achieve T₅₀ stability above 10 h under continuous operation at 500 mA cm⁻² and above 5 h at 1000 mA cm⁻², respectively. By using short electrical pulses, we significantly reduce the amount of dissipated thermal energy and show that this leads to reliable electrical operation up to 5 kA cm⁻² for such small perovskite LEDs fabricated on sapphire substrates.