Thin single screen-printed bifunctional titania layer photoanodes for high performing DSSCs via a novel hybrid paste formulation and process

A novel hybrid titania paste comprising aqueous-synthesized anatase (A) nanocrystalites and submicrometer-sized “sea urchin”-like rutile (R) particles that enables the construction of thin (5–6 μm) single-layer photoanodes with competitive power conversion efficiency is described. Owing to the high surface area of the dye (N719)-coated anatase film, the scattering properties of the unique rutile particulates, and the incorporation of P25 particles, the constructed bifunctional electrode films exhibit excellent electron transport properties (long electron lifetime) and no electrolyte diffusion resistance. Dye-sensitized solar cell devices built with the thin (5–6 μm) hybrid electrodes showed greatly improved power conversion efficiency (PCE), namely 7.04%, when compared to devices based on single anatase (4.20%), double-layer (A + R), or double thickness commercial benchmark paste (6.74%). This is an impressive result as less than 1/2 material was used in a single printed layer. Thinner films as the ones built here may prove particularly advantageous in using new noniodide electrolytes associated with slow diffusion rates.