Thick film high-performance carbon-based CsPbIBr2 perovskite solar cells vis nano-perovskite modified hot casting method

All-inorganic carbon-based CsPbIBr2 perovskite solar cells (PSCs) have attracted attention due to their more balanced performance and stability. The performance of the PSCs is highly dependent on the quality of the absorber films. Unfortunately, most high-performance films are prepared in a glove box and conventional preparation methods often produce perovskite films within 400 nm of thickness, which is detrimental to large area device fabrication and limits their commercial application. Here we had demonstrated a short chain ligands nano-CsPbIBr2 particles modified hot-casting method to deposit a perovskite film with thickness up to 800 nm. It was carried out by spin-coating a hot CsPbIBr2 precursor solution onto nano-CsPbIBr2 particles film on an electron transport layer (ETL), and then depositing nano-CsPbIBr2 particles on the precursor film again before annealing. The nano-CsPbIBr2 particles on the ETL promotes precursor solution crystallization and increased film thickness, and the nano-CsPbIBr2 particles on the precursor film promoted grain growth and reduced defects due to compositional deviations from stoichiometric ratios. The power conversion efficiency (PCE) of the PSCs fabricated by this method is up to 10.66 %. The unencapsulated PSCs still retain more than 85 % of the initial PCE when stored at ambient atmosphere (RH 50–60 %) for 10 days.