Highly efficient and stable perovskite solar cells with strong hydrophobic barrier via introducing poly(vinylidene fluoride) additive

Abstract Perovskite solar cells (PSCs) have become the promising next-generation photovoltaic devices due to their excellent photoelectric performances, and the power conversion efficiencies (PCEs) have experienced unprecedented rapid increase in recent years. However, to realize the practical application of PSCs, high performance and long-term stability are required and the preparation of high-quality perovskite film is the key. Herein, we adopt a simple and effective method to prepare high-quality perovskite films by introducing the poly(vinylidene fluoride) (PVDF) polymer additive with abundant hydrophobic F. As the growth template, the PVDF promotes the growth of perovskite crystal, improves the crystallinity and film morphology, thus reducing defect density and inhibiting carrier recombination. The results show that the photovoltaic performances of the perovskite device with PVDF are meaningfully improved, and a high PCE of 21.42% is achieved with an improvement of 10.87%. More importantly, the PVDF-based perovskites display greatly enhanced humidity and heat stability due to the protection of strong hydrophobic barrier from F and PVDF long chain. Aging at 45% ± 5% relative humidity (RH) for 2400 h and 85 °C for 300 h, respectively, the unsealed PVDF devices can maintain over 90% of the initial PCE. It indicates that suitable polymer additives can improve the film quality to acquire high-performance and stable PSCs and lay a foundation to design new perovskite light absorption layer with different polymers for the further development of PSCs.