Ambient-atmosphere fabricated perovskite solar cells with formamidinium iodide passivation for enhanced light absorption

The exceptional photoelectric characteristics and high conversion efficiency have positioned metal halide perovskite as a significant breakthrough in recent thin-film photovoltaic technology. Despite these advantages, perovskite crystalline lattices often contain defects like interstitials, vacancies, and impurities at grain boundaries and surfaces, along with dangling bonds, contributing to the nonradiative recombination processes among photocarriers, which hamper device performance and stability. In this context, we present a simple method to mitigate electronic defects occurring at the interface between perovskite (Cs0.17FA0.83Pb(I0.83Br0.17)3 films and the hole transport layer by applying organic salt, namely formamidinium iodide (FAI), in an eco-friendly isopropanol (IPA) antisolvent to treat the perovskite surface. Incorporating FAI reduces grain boundaries, enhances carrier transportation, and boosts power conversion efficiency from 13.59 % to 15.10 % under 1 sun measurement with an active area of 0.09 cm2. Similarly, under 1000 lx illumination, efficiency improves from 26.70 % to 28.69 %, with enhanced stability. This study offers a cost-effective and low-temperature method via the utilization of carbon electrodes to fabricate highly efficient planar perovskite solar cells under an air atmosphere, showcasing the potential for stable and economically viable photovoltaic solutions.