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Tuning Precursor-Amine Interactions for Light-Emitting Lead Bromide Perovskites.

Organic additives with amino moieties are effective in improving the properties of archetypical formamidinium (FA)-based hybrid perovskites for photovoltaic and light-emitting applications. However, a detailed understanding of how amino additives affect the perovskite materials is lacking, impeding developments in this area. Here, by investigating the interactions of lead bromide perovskite precursors with phenethylamine (PEA) and its derivatives with small variations in chemical structure, we reveal that only the secondary amine (N-methyl-2-phenylethylamine (N-PEA)) results in strengthened hydrogen bonds with FABr in precursor solutions, allowing the formation of high-quality perovskite films. The photoluminescence quantum efficiencies (PLQEs) of the resultant perovskite samples on widely used charge-transport substrates are retained to 82% of their original values, indicating reduced sensitivity to interfacial nonradiative traps critical to device applications. Using a standard device structure, green perovskite light-emitting diodes with peak external quantum efficiencies of 12.7% at ∼500 cd m-2 and operational lifetimes (T50) exceeding 10 h (at 100 cd m-2) are obtained.