High performance and stable perovskite solar cells modified with 8-hydroxyquinoline lead

The quality of the perovskite active layer is the critical factor that affects the photovoltaic performance of perovskite solar cells (PSCs). In this paper, the 8-hydroxyquinoline lead (Pbq₂) containing pyridine bonds, C–O bonds, and quinoline ring groups was introduced into the MAPbI₃ perovskite layer to improve the performances and stabilities of PSCs. The doped Pbq₂ could adjust the growth of perovskite crystals by coordinating interactions between the above functional groups in Pbq₂ with Pb²⁺, MA⁺, and I⁻ in perovskite together. And as a result, high-quality and dense perovskite films with larger grain sizes were obtained. At the same time, large molecule-sized Pbq₂ chelated at the grain boundary of perovskite, which passivated the defects and suppressed non-radiative recombination of photo carriers and ion migration at grain boundaries. Therefore, the interface energy barrier between the perovskite layer and the electron transfer layer (ETL) was reduced by the Pbq₂ doping, which accelerated the separation and transportation of carriers at the ETL/perovskite layer interface. Finally, Pbq₂-modified PSCs achieved a power conversion efficiency (PCE) of 20.82% with an open circuit voltage (V_oc) of 1.144 V and a fill factor (FF) of 77.4% compared to a PCE of 17.87% for the reference sample. Furthermore, Pbq₂-modified PSCs showed better light stability and moisture resistance in air conditions.