Additive treatment yields high-performance lead-free perovskite light-emitting diodes

Tin (Sn)-based perovskites are promising for realizing lead-free perovskite light-emitting diodes^1,2, yet achieving high efficiency devices remains a significant challenge due to the presence of high density of defects in Sn perovskites^3,4. The formation of defects in Sn perovskites is still not well understood. Here, by using in-situ spectroscopy, we reveal that major defects in Sn perovskites instantly form during the fast aggregation of clusters at the initial growth process (~15 s from the start of the spin-coating process) and ~80% of the luminescence intensity is quenched within 6 s. We further find that additives that form strong chemical interactions with tin (II) iodide in precursor solutions can effectively prevent the fast aggregation of clusters and avoid the formation of luminescence quenchers. With this approach, efficient near-infrared lead-free perovskite light-emitting diodes with an external quantum efficiency of 8.3% are demonstrated.