Abstract
Hybrid perovskite semiconductors represent a promising platform for color-tunable light emitting diodes (LEDs) and lasers; however, the behavior of these materials under the intense electrical excitation required for electrically-pumped lasing remains unexplored. Here, we investigate methylammonium lead iodide-based perovskite LEDs under short pulsed drive at current densities up to 620 A cm−2. At low current density (J < 10 A cm−2), we find that the external quantum efficiency (EQE) depends strongly on the time-averaged history of the pulse train and show that this curiosity is associated with slow ion movement that changes the internal field distribution and trap density in the device. The impact of ions is less pronounced in the high current density regime (J > 10 A cm−2), where EQE roll-off is dominated by a combination of Joule heating and charge imbalance yet shows no evidence of Auger loss, suggesting that operation at kA cm−2 current densities relevant for a laser diode should be within reach.
Highlights
Hybrid perovskite semiconductors represent a promising platform for color-tunable light emitting diodes (LEDs) and lasers; the behavior of these materials under the intense electrical excitation required for electrically-pumped lasing remains unexplored
At current densities less than 10 A cm−2, we find that the external quantum efficiency (EQE) depends strongly on the timeaveraged history of the pulse train and can change dramatically depending on the duty cycle or background bias, reaching a peak EQE of approximately 13.5%, which is well above that obtained under direct current (DC) operation
The impact of ions is less pronounced in the high current density regime (J > 10 A cm−2), where efficiency roll-off is dominated by a combination of Joule heating and charge imbalance, yet shows no evidence of Auger loss even at current densities exceeding 150 A cm−2
Summary
Hybrid perovskite semiconductors represent a promising platform for color-tunable light emitting diodes (LEDs) and lasers; the behavior of these materials under the intense electrical excitation required for electrically-pumped lasing remains unexplored. The impact of ions is less pronounced in the high current density regime (J > 10 A cm−2), where efficiency roll-off is dominated by a combination of Joule heating and charge imbalance, yet shows no evidence of Auger loss even at current densities exceeding 150 A cm−2 These results demonstrate that the efficiency of perovskite LEDs depends strongly on the manner in which they are driven and indicate that operation at kA cm−2 current densities relevant for electrically pumped lasing should be within reach
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