Amino-Acid Additive Engineering of Tin-Halide Perovskites Enables High-Efficiency and Bright Near-Infrared Light-Emitting Diodes

Tin (Sn)-halide perovskites are emerging environmentally-friendly candidates for achieving near-infrared light-emitting diodes with extended emission beyond their toxic lead counterparts. Despite the rapid development of Sn-based perovskite LEDs (PeLEDs), a thorough understanding and advanced modulations of the crystallization engineering of Sn-perovskites remain necessary to further boost the performance characteristics of state-of-the-art devices. Herein, the additive engineering of typical amino acids of L-phenylalanine (Phe) and L-tyrosine (Tyr) is comprehensively investigated in manipulating the efficient heterostructured Sn-perovskite emissive layers and ensuing PeLEDs. It is demonstrated that the Tyr possessing an additional reductive phenol moiety than that of Phe functions more effectively in retarding the fast crystallization and inhibiting the Sn²⁺ oxidation, ensuring the fabrication of Sn-perovskite emissive layers with high uniformity and enhanced luminescence properties. More importantly, the incorporated Tyr molecules induce increased electron density of Sn²⁺ nuclei, which promotes the formation of low-dimensional perovskite components at the bottom of the heterostructured emissive layers and enables more efficient charge injection in the resultant PeLEDs. The optimized Tyr-derived device demonstrates a high peak external quantum efficiency (EQE) of 13.2% along with a maximum radiance of 165 W sr⁻¹ m⁻², which sets a new benchmark for Sn-based near-infrared PeLEDs.