Solvent effect on the hole-conductor-free fully printable perovskite solar cells

Highlights: • Solvent effect was systematically studied on the hole-conductor-free fully printable MPSC. • Wettability of perovskite precursor, stability of intermediate phase affect the perovskite. • Relationship between solvent properties, perovskite precursor solution, intermediate phases and photovoltaic parameters. • DMF/DMSO (0.93:0.07, v/v) solvent-based device achieved a promising PCE of 13.89%. Solvent effect was systematically studied on the hole-conductor-free fully printable perovskite solar cells with pristine MAPbI₃ via one-step deposition. The contact angle measurement shows that the polarity and viscosity of solvents possess a significant effect on the wettability of perovskite precursor solution for both of mesoscopic carbon counter electrode films and metal dioxide layers. XRD and FTIR results confirm the existence of different intermediate phases whose stability is affected by their coordination ability with PbI₂. The wettability and the stability of intermediate phases influence the light harvesting ability and charge separation of the perovskite layer as confirmed by UV–visible absorption and steady-state PL results. Due to the suitable interplay and compromise of polarity, viscosity, wettability and coordination ability, DMF/DMSO (0.93:0.07, v/v) solvent-based device achieved a promising PCE of 13.89% under 100 mW cm⁻² simulated sunlight illumination.