Impact of the Incorporation of Nitrogen‐Containing Lewis Bases on the Enhancement of the Optoelectronic Properties of Hybrid MAPbI ₃ Perovskite Solar Cells

In this work, we introduce a technique to improve the properties of CH 3 NH 3 PbI 3 thin films by decreasing defects by employing a dual functional stable Lewis base additive. The multifunctional properties of Lewis base molecules, including phosphorus, nitrogen, and oxygen, are utilized to enhance the efficiency of the active layer via a widely adopted, rapid, cost‐effective method. These properties include an increase in the carrier lifetime, suppression of phase segregation, reduction of recombination, formation of large crystals, and high crystallinity. The Lewis base interacts with solution precursors to delay crystal formation and enhance crystallinity. The nucleation processes of the perovskites were improved by treating CH 3 NH 3 PbI 3 with a Lewis base, leading to the formation of pinhole‐free, compact, and large‐grain perovskite films measuring up to 1.1 μm for the Et 3 N Lewis base. Furthermore, the photoluminescence evanescence spectra, band structure, and light absorption of the CH 3 NH 3 PbI 3 films were investigated. The efficiency of power conversion efficiency (PCE) in solar cells can be improved through larger grain sizes in perovskite films, as this allows photogenerated carriers to face less resistance from bulk defects and grain boundaries. A high PCE of 18.3% can be achieved by triethylamine with N‐strong nitrogen‐containing Lewis base treatment.