Interstitial Rare-Earth Doping of FAPbI3 Perovskite Nanocrystals under Mild Ambient Conditions

The rare-earth (RE) metal doping strategies have been investigated for many applications in perovskite materials. However, prior approaches to synthesizing RE-doped perovskite nanocrystals (PNCs) have predominantly required harsh synthesis conditions, including an inert gas atmosphere and high temperatures. Here, we present a doping strategy using four RE ions (La3+, Nd3+, Gd3+, and Er3+) doped into FAPbI3 PNCs under mild conditions (50 °C) in an ambient atmosphere. Density functional theory calculations were performed to rationalize the RE incorporation by evaluating the formation energy of possible dopant configurations within the FAPbI3 lattice. The results demonstrated that RE ions were successfully introduced into interstitial sites in the FAPbI3 lattice under mild conditions. RE-doped FAPbI3 PNCs were demonstrated to preserve the structure of α-FAPbI3 PNCs, while improving the optical properties in colloidal and thin-film samples, delivering an enhanced power conversion efficiency of 18.65% in photovoltaic performance together with improved stability relative to pristine PNCs.