Thin films of tin (IV) oxide as an electron transport layer were deposited on perovskite in inverted perovskite solar cells on flexible ITO-PET substrate by blade coating. The deposition of metal oxide on perovskite to fabricate flexible perovskite solar cells on the ITO-PET substrates is mainly limited by the solvent incompatibility of the metal oxide dispersion medium with the underlying perovskite layer and the high processing temperature of metal oxides nanoparticles. So, for the scalable deposition of metal oxide on the perovskite in flexible ITO-PET based subtract, perovskite incompatible solvents need to be avoided and it is necessary to protect PET substrate from heat. In this study, we used solution phase synthesis of SnO2 nanoparticles and yttrium doped SnO2 nanoparticles. These pre-synthesized nanoparticles were functionalized with acetate through ligand exchange allowing their dispersion in anhydrous ethanol. The SnO2 dispersions were directly deposited on the perovskite by blade coating followed by air knife treatment and annealing below 100oC. There was no detectable damage to the underlying perovskite layer as evidenced by x-ray diffraction and scanning electron microscopy. Photoluminescence spectroscopy and device performance confirm effective electron extraction. The champion device shows 14.5% initial power conversion efficiency (PCE) which is unprecedented for an inverted device in flexible ITO-PET substrate employing SnO2 as an ETL. This talk will describe efforts in synthesis, functionalization, and formulation to achieve highly efficient large area flexible perovskite solar cells.

Large area deposition of low temperature processed SnO2 as an ETL in inverted perovskite solar cell on flexible ITO-PET based substrate

ACS Spring 2022

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