title: X-ray photoemission spectroscopy investigation of the interaction between 4-mercaptopyridine and the anatase TiO2 surface.
abstract: In polymer-metal oxide hybrid solar cells, an extremely careful engineering of the interface is required to ensure good device performances. Recently, very promising results have been obtained by functionalizing titanium dioxide (TiO2) by means of 4-mercaptopyridine (4-MPy) molecules, showing the beneficial effect of these molecules on the interface morphology. This study investigates the nature of the interaction of 4-MPy molecules with the TiO2 surface by means of X-ray photoemission spectroscopy. In order to mimic the device processing conditions, our analysis is carried out on molecules adsorbed from solution on a nanocrystalline surface. According to our analysis, 4-MPy molecules (C5H5NS) are likely bound with the oxide through the nitrogen atom. The bonding precedes either via a covalent interaction with Lewis surface sites, or via hydrogen mediation, possibly in the form of hydrogen bonds. Interestingly, in the latter case, we also observe strong changes in the spectroscopic features attributed to the thiol group.
authors.affiliation: CNISM and Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy. alberto1.calloni@mail.polimi.it
authors.forename: A
authors.initials: A
authors.lastname: Calloni
authors.forename: A
authors.initials: A
authors.lastname: Brambilla
authors.forename: G
authors.initials: G
authors.lastname: Berti
authors.forename: G
authors.initials: G
authors.lastname: Bussetti
authors.forename: E V
authors.initials: EV
authors.lastname: Canesi
authors.forename: M
authors.initials: M
authors.lastname: Binda
authors.forename: A
authors.initials: A
authors.lastname: Petrozza
authors.forename: M
authors.initials: M
authors.lastname: Finazzi
authors.forename: F
authors.initials: F
authors.lastname: Ciccacci
authors.forename: L
authors.initials: L
authors.lastname: Duò
mesh_terms: D000327:Adsorption; D003460:Crystallization; D056951:Photoelectron Spectroscopy; D011725:Pyridines / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D011725:Pyridines; C009495:titanium dioxide; C042861:4-thiopyridine; D014025:Titanium