Enhanced Open-Circuit Voltage and Improved Stability with 3-Guanidinoproponic Acid as the Passivation Agent in Blade-Coated Inverted Perovskite Solar Cells

The formation of high-density charge trap states along the surface and grain boundaries of the perovskite absorber is a major cause of recombination that limits the efficiency and quickly degrades the long-term stability of perovskite solar cells (PSCs). To improve the PSC performance, we investigated the use of amino acids with Lewis acid–base functional groups, namely, 2-guanidinoacetic acid, l-aspartic acid, l-glutamic acid, and 3-guanidinoproponaic acid (3gpa), as passivating dopants for blade-coated perovskite films. The best photovoltaic performance was achieved with 4 mol% 3gpa doping, which effectively passivated both positively and negatively charged defects, resulting in a 12.9% improvement in the open-circuit voltage and a high PCE of 19.83%. Additionally, the improved carrier lifetime and reduced defect density led to improved long-term stability in blade-coated PSCs.