High-Efficiency Quasi-2D Perovskite Light-Emitting Diodes Using a Dual-Additive Strategy Guided by Preferential Additive-Precursor Interactions

Quasi-2D perovskites are promising emitters in light-emitting diodes (LEDs) due to their natural quantum well (QW) structure and tunable exciton binding energy. Synergistic regulation of the defect passivation and QW width distribution of quasi-2D perovskites is crucial to achieve high-performance perovskite-based LEDs. Herein, a combination of two additives, i.e., 3-(diaminomethylidene)-1,1-dimethylguanidine (Metformin) and 1,4,7,10,13,16-hexaoxacyclooctadecane (Crown) having preferential interactions with different quasi-2D perovskite precursors is proposed to synergistically passivate the defects and regulate the QW width distribution of quasi-2D perovskites. Metformin additive interacts strongly with lead bromide, mainly passivating the defects. Crown additive has preferential interactions with organic spacer phenethylammonium bromide, which dominates the QW width distribution and induces quasi-2D perovskites with uniform dimensions. The dual additives of Metformin and Crown interact preferentially with distinct precursors, allowing to regulate the QW width distribution and defect density of quasi-2D perovskites synergistically. A photoluminescence quantum yield as high as 91.5% is achieved for the quasi-2D perovskite prepared with the dual-additive strategy. Moreover, high-efficiency quasi-2D perovskite LEDs were successfully fabricated with a maximum external quantum efficiency of 21.3% and a maximum luminance over 30 000 cd m(-2). This work provides a preferential interaction-guided dual-additive strategy to fabricate high-efficiency quasi-2D perovskite LEDs without anti-solvent treatment.