Boosting the performance of Quasi-2D perovskite Light-Emitting diodes by tailoring molecular configurations of Carboxyl-Based additives

Quasi two-dimensional (quasi-2D) perovskites have shown huge potential for perovskite light-emitting diodes (PeLEDs). Nevertheless, the serious non-radiative recombination induced by numerous defects in polycrystalline quasi-2D perovskite films hinders their further development. Herein, three carboxyl-based additives with different molecular configurations, i.e. butyric acid (BAC), glutaric acid (GAC) and tricarballylic acid (TAC), are adopted as passivation agents for quasi-2D PeLEDs. Benefiting from the strong coordination interaction between -COOH and perovskites, the inclusion of carboxyl-based additives can effectively optimize film morphologies, regulate the distribution of small-n phases, passivate defects and enhance film stability. With the increase of the carboxyl group number and molecular spatial dimension of carboxyl-based additives, more compact and smoother quasi-2D perovskite films, together with narrower phase distribution, lower defect density and better stability, can be obtained. Consequently, the unpacked quasi-2D PeLED treated with TAC, which is tested in the ambient air with the relative humidity of about 50 %, delivers an external quantum efficiency (EQE) of 14.21 % and prolonged operational lifetime (T50) of 2160 s, while the pristine device only gives an EQE of 7.63 % and T50 of 460 s. Our work provides guidance for boosting the performance of quasi-2D PeLEDs by rationally tailoring molecular configurations of carboxyl-based additives.