Optimization of perovskite ink for gravure printing

This study examines the formulation, stability, and processability of perovskite inks designed for gravure printing, with particular focus on the influence of ink rheology and layer morphology. The study investigates two fabrication approaches: inks produced from perovskite precursors and from dry-synthesized perovskite. It was found that ink rheology systematically correlates with dissolution time and storage duration, with extended dissolution (5 h) improving homogeneity and reducing non-ideal solar cell behavior. However, longer ink aging results in gradual viscosity changes and a decline in cell performance. Although dry-synthesized perovskite inks demonstrated better rheological stability, both types experienced similar losses in photovoltaic performance due to aging. The inks were based on a double cation perovskite [FA0.83Cs0.17Pb(I0.93Br0.07)3] dissolved in dimethyl sulfoxide and mixed with starch and methylammonium chloride additives to achieve suitable rheology for gravure printing. Structural, optical, and morphological analyses revealed that ink aging leads to compositional redistribution and blue-shifting of the optical bandgap, ultimately restricting cell efficiency. The findings show that ink rheology alone cannot predict device performance, emphasizing the importance of ink preparation and aging for gravure-printed solar cells. This research offers valuable insights into optimizing perovskite inks and the role of additives, advancing scalable, cost-effective fabrication of flexible perovskite solar cells.