Solvent engineering of SnO2 ETL for enhanced performance of carbon-based CsPbIBr2 PSCs

This study thoroughly investigates the effects of different solvent engineering strategies on the structure and properties of SnO 2 electron transport layers (ETLs) and evaluates their performance-enhancing effects on carbon-based all-inorganic CsPbIBr 2 perovskite solar cells (PSCs). By comparing the SnO 2 ETLs prepared with ethanol (ET-SnO 2 ) and isopropanol (IPA-SnO 2 ) solvents and constructing corresponding CsPbIBr 2 PSCs devices, we comprehensively analysed the structure, morphology, wettability, light transmittance and electronic transport properties of the SnO 2 ETLs using characterization methods such as XRD, SEM, contact angle measurement, transmission spectroscopy, steady-state fluorescence spectroscopy and electrochemical impedance spectroscopy. Combined with the J-V characteristics of the device, we revealed the mechanism of the effect of solvent engineering on the performance of PSCs. The results showed that IPA-SnO 2 exhibited better performance with lower contact angle and higher compactness, which is conducive to electron transport and reduces interfacial defects. IPA-SnO 2 also promoted the growth of CsPbIBr 2 crystals, forming larger and denser crystal structures and reducing pinhole defects. In addition, IPA-SnO 2 improves the light transmittance of the FTO substrate and the light absorption of the CsPbIBr 2 film, thereby increasing the light trapping efficiency. Finally, the IPA-SnO 2 -based PSCs achieved a PCE of 5.95%, an improvement of 25% compared to ET-SnO 2 , demonstrating good application prospects. This study provides an important experimental basis for optimizing the preparation process of SnO 2 ETL and improving the performance of carbon-based CsPbIBr 2 PSCs. Graphical