Managing photons and carriers by multisite chiral molecules achieving high-performance perovskite solar cells fabricated in ambient air

The progress of photovoltaic performance is hampered by photon and carrier losses in the electron transport layer (ETL) of conventional n-i-p perovskite solar cells (PSCs). Herein, we propose a simple and effective approach to reduce photon and carrier losses. The multisite chiral molecule L-histidine hydrochloride monohydrate (LHHM) is employed to manipulate SnO2 ETL. The LHHM can not only inhibit the agglomeration of SnO2 nanoparticles but also effectively passivate oxygen vacancy and/or uncoordinated Sn4+ defects by multiple active sites and multiple chemical bonds, which is translated into increased light transmittance and enhanced electron mobility, minimizing photon and carrier losses in ETL. Moreover, the bottom-up defect passivation is realized by LHHM modification. The LHHM incorporation also improves interfacial energy band alignment, facilitates perovskite crystallization and releases tensile stress, which minimizes bulk and interfacial nonradiative recombination. The target device demonstrates a power conversion efficiency (PCE) of 25.06%. This is one of the highest PCEs for devices made in ambient air that has ever been documented. Furthermore, after 1000 hours of aging at 65 °C, under one sun's irradiation, and under 20-25% relative humidity, the unencapsulated target devices retain 94%, 81%, and 88% of their initial PCEs.