One-Step Blade Coating of Inverted Double-Cation Perovskite Solar Cells from a Green Precursor Solvent

Perovskite solar cells (PSCs) have recently gained power conversion efficiencies (PCEs) of up to 25.5% on a lab scale, which are nearly exclusively processed from precursor solutions involving harmful and polluting solvents like dimethylformamide (DMF). However, solution processing of green and environmentally safe solvents such as dimethyl sulfoxide (DMSO) via scalable printing is challenging mainly because of two reasons: first is the pronounced precursor solution dewetting on the subjacent layer and second its complex quenching process. In this work, we report on one-step blade coating of inverted (p-i-n) double-cation PSCs using solely DMSO at low processing temperatures. To avoid dewetting of the DMSO-based solution on the hydrophobic hole transport layer (HTL) and to realize adequate quenching, a blade-coated wetting agent of silicon oxide nanoparticles at the HTL/perovskite interface and gas stream-assisted drying are applied, respectively. Trends in absorber grain size, morphology, crystallinity, and elemental composition of samples from both toxic and green solvent concepts are compared, revealing analogous findings. Consequently, PSCs blade-coated from DMSO achieve PCEs of up to 16.7% on a 0.24 cm2 active area comparable to the ones from a DMF:DMSO mixture (16.9%), thus demonstrating that using toxic DMF is unnecessary. This represents an important step for bringing PSCs solution-processed from environmentally friendly precursor solvents closer to industrial implementation.