Over 24% Efficient Poly(vinylidene fluoride) (PVDF)-Coordinated Perovskite Solar Cells with a Photovoltage up to 1.22 V

Recently, organic–inorganic metal halide perovskite solar cells (PSCs) have achieved rapid improvement, however, the efficiencies are still behind the Shockley–Queisser theory mainly due to their high energy loss (E_LOSS) in open-circuit voltage (V_OC). Due to the polycrystalline nature of the solution-prepared perovskite films, defects at the grain boundaries as the non-radiative recombination centers greatly affect the V_OC and limit the device efficiency. Herein, poly(vinylidene fluoride) (PVDF) is introduced as polymer-templates in the perovskite film, where the fluorine atoms in the PVDF network can form strong hydrogen-bonds with organic cations and coordinate bonds with Pb²⁺. The strong interaction between PVDF and perovksite enables slow crystal growth and efficient defect passivation, which effectively reduce non-radiation recombination and minimize E_LOSS of V_OC. PVDF-based PSCs achieve a champion efficiency of 24.21% with a excellent voltage of 1.22 V, which is one of the highest V_OC values reported for FAMAPb(I/Br)₃-based PSCs. Furthermore, the strong hydrophobic fluorine atoms in PVDF endow the device with excellent humidity stability, the unencapsulated solar cell maintain the initial efficiency of >90% for 2500 h under air ambient of ≈50% humid and a consistently high V_OC of 1.20 V.