Efficient Two-Dimensional Tin Halide Perovskite Light-Emitting Diodes via a Spacer Cation Substitution Strategy

Lead halide perovskites have attracted tremendous attention due to their impressive optoelectronic properties. However, the toxicity of lead remains to be a bottleneck for further commercial development. Two-dimensional Ruddlesden-Popper tin-based perovskites are lead-free and more stable compared to their 3D counterparts, which have great potential in the optoelectronic device field. Herein, we demonstrated high-quality 2D phenylethyl ammonium tin-iodide perovskite (PEA2SnI4) thin films by dropping toluene as anti-solvent. Furthermore, the PeLED performance is greatly improved by replacing PEAI spacer cation with 2-thiopheneethyllamine iodide (TEAI). As a result, the TEA-based PeLED device is achieved with a low turn-on voltage of 2.3V, a maximum luminance of 322 cd m-2 and maximum external quantum efficiency of 0.62%, which is the highest efficiency and brightness for pure red (emission peak=638 nm) tin-based PeLEDs so far.