Suppressed Voltage Deficit and Degradation of Perovskite Solar Cells by Regulating the Mineralization of Lead Iodide.

Both the uncoordinated Pb 2+ and excess PbI 2 in perovskite film will create defects and perturb carrier collection, thus leading to the open-circuit voltage (V OC ) loss and inducing rapid performance degradation of perovskite solar cells (PSCs). Herein, an additive of 3-aminothiophene-2-carboxamide (3-AzTca) that contains amide and amino and features a large molecular size is introduced to improve the quality of perovskite film. The interplay of size effect and adequate bonding strength between 3-AzTca and uncoordinated Pb 2+ regulates the mineralization of PbI 2 and generates low-dimensional PbI 2 phase, thereby boosting the crystallization of perovskite. The decreased defect states result in suppressed nonradiative recombination and reduced V OC loss. The power conversion efficiency (PCE) of modified PSC is improved to 22.79% with a high V OC of 1.22 V. Moreover, the decomposition of PbI 2 and perovskite films is also retarded, yielding enhanced device stability. This study provides an effective method to minimize the concentration of uncoordinated Pb 2+ and improve the PCE and stability of PSCs.