Mn-doped 2D Sn-based perovskites with energy transfer from self-trapped excitons to dopants for warm white light-emitting diodes

Mn-doped 2D perovskite powders are promising phosphors for warm white light-emitting diodes (LEDs). However, it remains a challenge to solve the problem of lead toxicity and improve the photoluminescence quantum yields (PLQYs). Here, we have successfully prepared Mn-doped 2D Sn-based perovskite materials ((C8H17NH2)(2)Sn1-xMnxBr4). The PLQYs of (C8H17NH2)(2)Sn1-xMnxBr4(x= 0.26) powders reach up to 42%. The as-prepared (C8H17NH2)(2)Sn(1-x)Mn(x)Br(4)exhibits a single broad photoluminescence (PL) band, differing from the dual peaks of Mn-doped lead halide perovskite quantum dots. Theoretical conclusions and experimental results show the competitive relationship between self-trapped exciton (STE) emission from the host crystal and dopant Mn d-d transition emission. With increasing Mn dopant concentration, the PL spectra exhibit red shifts and the full width at half-maximum (FWHM) becomes larger, which is constructive for warm white LEDs. The fabricated warm white LEDs based on (C8H17NH2)(2)Sn(1-x)Mn(x)Br(4)show a warm white light correlated color temperature (CCT; 3542 K) and a high color-rendering index (R-a, 88.12). Our work provides new possibilities for optoelectronic devices based on lead-free perovskite materials.