Expanding the solvent diversity and perovskite compatibility of SnO2 inks that are directly deposited on perovskite layers

Tin oxide (SnO₂) is an attractive electron transport material (ETM) for perovskite solar cells (PSCs) due to its optoelectronic properties, low-temperature solution processability, cost, and stability. However, solvent incompatibilities have largely limited its application to devices with SnO₂ deposited below the perovskite. To expand its utility in other device structures, including inverted PSCs and tandem devices, alternate deposition strategies are needed. This study addresses the solvent scope and perovskite compatibility of acetate-stabilized yttrium-doped SnO₂ (Y:SnO₂) dispersions. We show that dispersions in several lower alcohols and select polar aprotic solvents can be directly deposited on perovskite using scalable and low-temperature processes. Further, they are compatible with various perovskite formulations, including those with mixed cations and mixed anions. The study expands the applicability of SnO₂ as a solution-processible and cost-effective ETM as an alternative to fullerene-based organic ETMs and serves as a guide for its use in PSCs and tandem devices.