Mid-infrared HgTe Colloidal Quantum Dot LEDs

Mid-infrared HgTe colloidal quantum dot electroluminescent devices are demonstrated. With emission at 4 μm, devices achieved an external quantum efficiency of ∼10^-3 and power conversion efficiency of ∼10^-4 under biases of a few volts. The power conversion efficiency benefited from lowering the transparent electrode resistance through the incorporation of a metal conductive grid. The average power emitted was about 16 μW at 2 V bias with 50% duty cycle and a 1 mm² device. The room-temperature electroluminescence efficiency at low current was limited by the photoluminescence efficiency of the quantum dots, while the diode structure provided efficient electron-hole recombination.