Aqueous, Screen-Printable Paste for Fabrication of Mesoporous Composite Anatase-Rutile TiO2 Nanoparticle Thin Films for (Photo)electrochemical Devices

Mesoporous TiO2 films are employed in solar cells, lithium ion batteries, and air and water purification systems, to name a few applications. Film fabrication via coating the substrate with an organic suspension or paste carrying TiO2 nanoparticles is a common method. To lessen the adverse environmental impact, use of water as a solvent and nontoxic chemicals is being preferred over commonly used organic components. In this research, a water based, nano-TiO2 printable paste formulation with polyethylene glycol (MW 20 000) and propylene glycol was developed and seamlessly interfaced with TiO2 aqueous synthesis for sustainable manufacturing. The innovative combination of propylene glycol and polyethylene glycol is demonstrated to lead to improved paste rheology and sintered film properties. Dye-sensitized solar cells were assembled from the screen-printed films, and the effect of film surface area and porosity on photovoltaic performance was studied. The new aqueous-based paste yielded comparable power conversion efficiency to benchmark organic-based paste made of alpha-terpineol, ethyl cellulose, and ethanol, opening the avenue for lower cost, green fabrication of mesoporous thin film electrodes.