Achieving over 10% Efficiency in N719 Dye-Sensitized Solar Cells by Introducing Oblique-Angle Electrospray TiO ₂ Deposition

Breaking the 10% efficiency barrier for N719-based dye-sensitized solar cells (DSSCs) using scalable, nonvacuum deposition methods remains challenging, primarily owing to the limited control over the photoanode microstructure. In this study, we present a reproducible vertical/oblique electrospray deposition strategy to precisely tailor the morphology of TiO 2 photoanode films. While conventional vertical spraying (90°) often results in nonuniform films because of large droplet deposition, an oblique spray angle (45°) promotes the formation of dense, microstructured TiO 2 aggregates with improved uniformity. These aggregates serve a dual purpose: inducing a haze effect, which significantly enhances light scattering, and enhancing interparticle connectivity, which facilitates charge transport. Consequently, the optimized vertical/oblique bilayer photoanode achieves a high power conversion efficiency of 10.57%, significantly surpassing the 8.87% value observed in vertically sprayed monolayers. Validated through statistical analysis across ≥27 devices per group, this dual-angle electrospray deposition protocol offers a robust, cost-effective, and scalable method for fabricating high-efficiency DSSCs under ambient conditions.