Stronger binding force improving surface passivation of perovskites for High-Performance inverted solar cells

The surface properties of perovskites to a large extent affect the charge carrier dynamics of perovskites, which is critical to realize highly efficient and stable perovskite solar cells (PSCs). Herein, the surface properties of the perovskite are manipulated using dimethylamine hydroiodide (DMAI) and 1-[4-(Trifluoromethyl) phenyl] hydrazine hydrochloride (TFMPHC) synergistic system for inverted planar PSCs with a p-i-n device architecture. The results of systemically experimental studies and theoretical calculations reveal that the DMAI and TFMPHC could be chemically coupled through N-H···F hydrogen bond, which could significantly enhance the binding force for the DMAI-TFMPHC system and the perovskites. The DMAI-TFMPHC system shows a stronger binding force with the perovskite than that of the single passivating agent, thereby improving the passivation effect of perovskite films. Meanwhile, the DMAI-TFMPHC treatment could make a more n-type perovskite surface, facilitating the charge extraction and reducing interfacial nonradiative recombination at the interface of the perovskite/electron transport layer. Due to a combination of the stronger binding force and hydrophobicity of trifluoromethyl, the DMAI-TFMPHC-based inverted PSC shows superior photovoltaic performance and stability.