Highly Efficient Dual-Gated Light-Emitting Diodes Based on Suspended Monolayer WSe ₂

Suspended transition metal dichalcogenides (TMDCs) have shown much higher emission efficiencies than their supported counterparts due to the absent quenching effects; however, their application in light-emitting diodes (LEDs) has remained largely unexplored. Here, we designed and fabricated the dual-gated P-S(suspended)-N LEDs using the bipolar monolayer WSe₂. The suspended WSe₂ exhibited over 5-times higher photoluminescence quantum yield (PLQY) than the supported flakes, peaking at ∼28.8%, which is attributed to the deprivation of substrate-induced defect traps that typically facilitate nonradiative recombination. Besides, bright electroluminescence (EL) was observed from the electrostatically defined P-S-N junctions, achieving a maximal external quantum efficiency of ∼4.2% at room temperature, an order of magnitude higher than that of the reported P-I(intrinsic)-N junctions. Aside from the enhanced PLQY, such extraordinary EL performance also originates from improved carrier injection efficiency and light outcoupling of the suspended region, highlighting the promise of suspended TMDCs for efficient on-chip light sources.