title: Combined experimental and theoretical investigation of the hemi-squaraine/TiO2 interface for dye sensitized solar cells.
abstract: A simple hemi-squaraine dye (CT1) has been studied as a TiO2 sensitizer for application in dye sensitized solar cells (DSCs) by means of a combined experimental and theoretical investigation. This molecule is a prototype dye presenting an innovative anchoring group: the squaric acid moiety. Ab initio calculations based on Density Functional Theory (DFT) predict that this acid spontaneously deprotonates at the anatase (101) surface forming chemical bonds that are stronger than the ones formed by other linkers (e.g. cathecol and isonicotinic acid). Moreover an analysis of the electronic structure of the hybrid interface reveals the formation of a type II heterostructure ensuring adiabatic electron transfer from the molecule to the oxide. DSCs containing hemi-squaraine dyes were assembled, characterized and their performances compared to state of the art cells. Experimental results (large incident photon-to-electron conversion efficiency and an efficiency of 3.54%) confirmed the theoretical prediction that even a simple hemi-squaraine is an effective sensitizer for TiO2. Our study paves the way to the design of more efficient sensitizers based on a squaric acid linker and specifically engineered to absorb light in a larger part of the visible range.
authors.affiliation: Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Turin, Italy. giancarlo.cicero@polito.it
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Cicero
authors.forename: Giorgia
authors.initials: G
authors.lastname: Musso
authors.forename: Andrea
authors.initials: A
authors.lastname: Lamberti
authors.forename: Bruno
authors.initials: B
authors.lastname: Camino
authors.forename: Stefano
authors.initials: S
authors.lastname: Bianco
authors.forename: Diego
authors.initials: D
authors.lastname: Pugliese
authors.forename: Francesca
authors.initials: F
authors.lastname: Risplendi
authors.forename: Adriano
authors.initials: A
authors.lastname: Sacco
authors.forename: Nadia
authors.initials: N
authors.lastname: Shahzad
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Ferrari
authors.forename: Barbara
authors.initials: B
authors.lastname: Ballarin
authors.forename: Claudia
authors.initials: C
authors.lastname: Barolo
authors.forename: Elena
authors.initials: E
authors.lastname: Tresso
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Caputo