Single-step SnO deposition enabled by colloidal engineering with additive polyoxyethylene tridecyl ether and carbon nanodots for simplified and effective perovskite solar cells in low-light applications.

The quality of nanoparticle dispersibility in the colloidal state is crucial for depositing a homogeneous electron transporting layer (ETL) film, which directly affects charge transport in perovskite solar cells (PSCs). Tin oxide (SnO), a common ETL material, poses challenges due to surface defects caused by nanoparticle agglomeration in its colloidal solution. To address this, polymer and carbon nanodots were added to the precursor, which offers a simple, time-saving, and cost-effective strategy. This work introduces a single-step deposition method for preparing a high-quality SnO ETL by simultaneously incorporating water-soluble polyoxyethylene tridecyl ether (PTE), commonly found in household products, and carbon nanodots into a SnO colloidal solution. This approach effectively prevents nanoparticle agglomeration, ensures uniform SnO coating on fluorine-doped tin oxide (FTO) substrates, and reduces surface roughness. Additionally, the carbon nanodots improve the film's electrical conductance. Together, these additives improve charge transport and suppress recombination at the SnO/perovskite interface. Under the ISOS-D1 stability protocol, devices with dual additives retained 86 % of their initial efficiency after 1200 h, compared to 65 % for the control. Performance improvements were also seen under AM 1.5G illumination and were especially notable under low-light (1000 lx) conditions, in which the dual-additive device achieved 32.29 %, significantly higher than the control's 18.65 %. This approach is also effective with alcohol-based SnO precursors, highlighting its versatility. Overall, this method offers a simple, scalable, and cost-efficient route to produce high-quality SnO films, making it suitable for industrial-scale photovoltaic device production.