High-efficiency and stable FA(0.75)MA(0.25)SnI(3) perovskite solar cells with large-size crystal grains prepared by doping with multifunctional chloride salt

Although tin (Sn)-based perovskite stands out among numerous lead-free perovskite materials due to its suitable band gap and low toxicity, Sn-based perovskite solar cells (PSCs) still have problems with excessive internal defects and poor stability. Here, we introduce a passivation material 1,2,4,5-benzenetetramine tetrahydrochloride (C6H2(NH2)(4)& BULL;4HCl) with Cl- and -NH3+ into the FA(0.75)MA(0.25)SnI(3) perovskite. The research results indicate that the introduction of Cl can promote the generation of large-sized grains. The introduction of C6H2(NH2)(4)& BULL;4HCl through NHMIDLINE HORIZONTAL ELLIPSISI can effectively passivate the internal defects of perovskite films and capture free I-, thereby improving the crystallinity and quality of the films. By adjusting and optimizing the concentration of C6H2(NH2)(4)& BULL;4HCl, the light absorption of the FA(0.75)MA(0.25)SnI(3) film with the addition of 0.7 mol% C6H2(NH2)(4)& BULL;4HCl additive was enhanced, the defect density and unnecessary non-radiative recombination were reduced, and the oxidation of Sn2+ was inhibited. Finally, the C6H2(NH2)(4)& BULL;4HCl-incorporated FA(0.75)MA(0.25)SnI(3) device achieved the best power conversion efficiency (PCE) of 9.83%, and remained at an initial efficiency of 80% after being placed in a glove box under an N-2 environment for 850 hours (not encapsulated).