Direct Deposition of Nonaqueous SnO2 Dispersion by Blade Coating on Perovskites for the Scalable Fabrication of p-i-n Perovskite Solar Cells

Tin(IV) oxide materials have been extensively used as electron transport materials in n-i-p perovskite solar cells (PSCs) due to their superior optoelectronic properties, low-temperature processability, and high chemical stability. However, solvent incompatibility and processing temperature have limited the direct deposition of fully solution-processed SnO2 in p-i-n devices. In this study, we overcome this limitation by the functionalization of SnO2 nanoparticles with acetate through ligand exchange, allowing their dispersion in anhydrous ethanol. The SnO2 dispersion was deposited on the perovskite absorber by blade coating without damaging the underlying perovskite layer, as determined by X-ray diffraction and scanning electron microscopy. Photoluminescence spectroscopy confirmed effective electron extraction. The champion device shows 14.1% initial power conversion efficiency (PCE) which is unprecedented for a p-i-n device employing solution-phase SnO2. PSCs stored for 40 days in a nitrogen flow box retained an average of 95.8% of the initial PCE.