title: Low-temperature crystalline titanium dioxide by atomic layer deposition for dye-sensitized solar cells.
abstract: Low-temperature processing of dye-sensitized solar cells (DSCs) is crucial to enable commercialization with low-cost, plastic substrates. Prior studies have focused on mechanical compression of premade particles on plastic or glass substrates; however, this did not yield sufficient interconnections for good carrier transport. Furthermore, such compression can lead to more heterogeneous porosity. To circumvent these problems, we have developed a low-temperature processing route for photoanodes where crystalline TiO2 is deposited onto well-defined, mesoporous templates. The TiO2 is grown by atomic layer deposition (ALD), and the crystalline films are achieved at a growth temperature of 200 °C. The ALD TiO2 thickness was systematically studied in terms of charge transport and performance to lead to optimized photovoltaic performance. We found that a 15 nm TiO2 overlayer on an 8 μm thick SiO2 film leads to a high power conversion efficiency of 7.1% with the state-of-the-art zinc porphyrin sensitizer and cobalt bipyridine redox mediator.
authors.affiliation: Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), Station 6, 1015 Lausanne, Switzerland.
authors.forename: Aravind Kumar
authors.initials: AK
authors.lastname: Chandiran
authors.forename: Aswani
authors.initials: A
authors.lastname: Yella
authors.forename: Morgan
authors.initials: M
authors.lastname: Stefik
authors.forename: Leo-Philipp
authors.initials: LP
authors.lastname: Heiniger
authors.forename: Pascal
authors.initials: P
authors.lastname: Comte
authors.forename: Mohammad K
authors.initials: MK
authors.lastname: Nazeeruddin
authors.forename: Michael
authors.initials: M
authors.lastname: Grätzel