A binary solvent strategy regulated by the aqueous component: A simplified pathway to high-performance and stable CsPbBr₃ perovskite cells

The study utilizes a binary solvent system comprised of Water and Methanol (WMe) to dissolve CsBr. • A tailored WMe binary solvent enables synthesis of high-quality CsPbBr₃ films via two-step spin-coating. • The perovskite solar cells fabricated using this method achieve a peak power conversion efficiency (PCE) of 6.59%. • After 30 days of exposure to ambient air, the PCE of unencapsulated devices remained at 87% of its initial value. Carbon-based CsPbBr 3 perovskite solar cells attract significant interest for their long-term stability and facile fabrication in humid environments. However, fabricating high-quality CsPbBr 3 films via conventional spin-coating remains challenging due to the large solubility difference between PbBr 2 and CsBr. In this context, a binary solvent system comprising Water and Methanol is employed for CsBr dissolution, where in the CsBr solubility is tailored by modulating the water proportion to achieve a fitting stoichiometric balance with PbBr 2 . Eventually, a high-quality CsPbBr 3 film is synthesized through a two-step spin-coating procedure. The film is then integrated into an FTO/c-TiO 2 /m-TiO 2 /CsPbBr 3 /carbon solar cell, yielding a power conversion efficiency (PCE) of 6.59%. Remarkably, even after 30 days of unencapsulated exposure to ambient air, the PCE retains 87% of its initial value. Furthermore, the effects of precursor solubility and solvent composition on CsPbBr 3 crystallization process are explored, providing valuable insights for selecting novel solvents for high-performance CsPbBr 3 solar cells. Download: Download high-res image (129KB) Download: Download full-size image