Enhanced efficiency and stability of Sn-based perovskite light-emitting diodes through interfacial engineering using mandelhydrazine

The pursuit of environmentally friendly and sustainable optoelectronics has spurred considerable interest in tin-based perovskite light-emitting diodes (Sn-PeLEDs). However, a major obstacle to the performance lies in the inherent instability of Sn²⁺, which readily oxidizes to Sn⁴⁺ and introduces a high density of Sn vacancies. Herein, we report a multifunctional interface engineering strategy by introducing mandelhydrazine (MH) into the PEDOT:PSS hole-transport layer (HTL). The incorporated MH induces strong interface interaction, guiding the crystallization of the overlying perovskite film for enhanced film quality, effectively passivating interfacial defects and inhibiting the oxidation of Sn²⁺. These synergistic effects contribute to a significant enhancement in the performance of PEA₂SnI₄ PeLEDs, which exhibit pure red emission at 624 nm. The resulting Sn-PeLEDs achieve a peak external quantum efficiency (EQE) of 0.85 % and a maximum luminance of 180 cd m⁻², both double the values for the control devices. In addition, the device operational stability is greatly improved. This work demonstrates an effective interfacial modification approach for developing high-performance, lead-free PeLEDs.