Enhancement of mid-infrared electroluminescence in black phosphorus with an electron blocking layer

Black phosphorus (BP) has been demonstrated to have a high light-emitting efficiency in the mid-infrared regime due to its direct bandgap and suppressed Auger recombination effect. Optimization of device structures can further boost the light-emitting efficiency. Here, we introduce a p-WSe2/BP/n-MoS2 heterostructure for mid-infrared light-emitting diodes (LEDs). The p-type WSe2 and n-type MoS2 layers serve as the electron and hole blocking layers, respectively, which significantly enhances the electron–hole recombination probability in BP and hence the external quantum efficiency (EQE) of the device. Peak EQEs of 0.58% and 1.09% are achieved at 300 and 80 K, respectively. Our results confirm that p-type WSe2 is an effective electron blocking layer for high-efficiency BP LEDs.