Enabling AC electroluminescence in quasi-2D perovskites by uniformly arranging different-n-value nanoplates to allow bidirectional charge transport

Perovskite light-emitting diodes (LEDs) are normally operated under forward direct current (DC) to realize electron/hole injection at cathode/anode surfaces. Here, we demonstrate an alternating current (AC) driven LED enabled by bi-directionally allowed charge transport in quasi-2D perovskite (PEA₂MA_n−1Pb_nI_3n+1) film. Essentially, the bi-directional charge transport is realized by uniformly arranging different-n-value 2D nanoplates together with symmetrically designed anode/cathode interfaces, which can allow injected electrons and holes to form light-emitting states under both forward and reverse biases, leading to an AC electroluminescence (EL) with the device architecture of ITO/PEI/PEDOT:PSS/PEA₂MA_n−1Pb_nI_3n+1/P3HT/PEI/Ag. The high AC EL performance was achieved with the radiance = 24 W Sr⁻¹ m⁻² and 18.3 W Sr⁻¹ m⁻² and EQE = 12.5% and 3.7% under forward and reverse biases. The device-operational stability was largely improved with the half-intensity time of T₅₀ = 11.0 h under AC bias (+2 V/−2 V, 50 Hz) as compared to T₅₀ = 3.9 h under forward bias (+2 V/0 V, 50 Hz).