Design schemes for achieving highly efficient lead sulfide colloidal quantum dot-based shortwave infrared light emitting diodes

Colloidal quantum dots (CQDs)-based near and shortwave infrared (SWIR) light emitting diodes (LEDs) have significantly advanced in recent years. Despite the improvement, the performance is still inferior to that of their counterparts in the visible range. Developing a device simulation methodology is vital to studying the loss mechanism and reducing the losses to achieve high-performance SWIR LEDs. Here, we report a novel technique to simulate lead sulfide (PbS) CQD-based SWIR LED performance using 1-dimensional Solar Cell Capacitance Simulation (SCAPS-1D) software. The platform solves the basic semiconductor equations to estimate the radiative and non-radiative recombination in the active layer. The role of various material parameters like emitter bandgap, trap density, recombination coefficients, and band offset for charge injection on device performance was investigated. The simulation shows that the most dominating loss factor for PbS LEDs in higher injection domains is the Auger recombination, whereas, in lower voltage regimes, trap-assisted non-radiative recombination pathways are prominent. The simulation validates the experimentally reported device performances and guides the roadmap for achieving external quantum efficiency above 20% in these devices.