DI-UMONS : Dépôt institutionnel de l’université de Mons

Recherche transversale
(titres de publication, de périodique et noms de colloque inclus)
2016-12-01 - Colloque/Présentation - poster - Anglais - 1 page(s)

Panepinto Adriano , Dervaux Jonathan, Cormier Pierre-Antoine, Snyders Rony , "Synthesis of TiO2:N by co-reactive magnetron sputtering for dye-sensitized solar cell applications" in Int’l conference “Reactive sputter deposition 2016” (RSD-2016), Dec 1-2 2016, Ghent, Belgique, 2016

  • Codes CREF : Chimie (DI1300)
  • Unités de recherche UMONS : Chimie des interactions plasma-surface (S882)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)

Abstract(s) :

(Anglais) Many efforts have been devoted to improve the photocatalytic performances of titanium dioxide (TiO2) by doping it with non-metal elements [1]. In comparison, few studies have been conducted on the doping of TiO2 for solar cell applications. However, the charge transport in the TiO2 photoanode is a critical aspect to optimize the dye-sensitized solar cells (DSSCs) efficiently. By the TiO2 doping, the number of charge carriers increases which leads to a higher conductivity of the film and finally a better charge transport. Indeed, as the crystalline structure and the microstructure, the conductivity of the TiO2 thin films is a key parameter to develop DSSCs. In a previous work [2], we showed that nanostructured TiO2 thin films can be synthesized by glancing angle reactive magnetron sputtering (GLAD-RMS). This method allows a fine control of the chemical composition, the crystalline structure and the morphology of the films. In the present work, N2 was introduced in the discharge in order to synthesize N doped TiO2 thin films. After to have studied the poisoning mechanisms of the Ti target sputtered injecting O2 and N2 separately, the influence of the reactive gas flows, as well as their positions of injection (at the substrate or at the target), on the crystalline, the chemical and the electrical and the optical properties of the films were investigated. These properties were determined by XRD, by XPS, by Hall effect measurements, and by UV-visible spectroscopy, respectively. All experiments were first performed on dense thin films (depositions under normal incidence). Preliminary data reveal that the doping element concentration and the substitutional or interstitial incorporation can be controlled by the experimental conditions. In order to increase the substitutional nitrogen part in the film, the oxygen flux in the discharge has to be low, meaning before the poisoning of the target occurs (for 10 % of O2 flow). Moreover, the nitrogen flux has to be high (15%), ideally after the transition Ti/TiN. Nevertheless, the transmittance rapidly decreases (T = 5% for 10% of N) with the nitrogen content in the film. The results also reveal that the sputtering of the target in the oxy-nitride regime (high O2 and N2 flows), favors the formation of p-type TiO2:N thin films. In this case, the hole mobility was between 1 and 3 cm2.V-1.s-1, which is similar than the one of NiO nanoparticules generally use as photocathode in p-type DSSC [3]. Nevertheless, the films were mainly composed by TiN phase due to the high N concentration. This was detrimental for the transmission of the films: T<45%. Finally, N doped TiO2 and nanostructured (glancing angle depositions) thin films showing a n-type conductivity were successfully synthesized. [1] M. V. Dozzi et al, J. Photochem. Photobiol. C Photochem. Rev., vol. 14, pp. 13–28, Mar. 2013. [2] J. Dervaux et al., Vacuum, vol. 114, pp. 213–220, Nov. 2014. [3]Y.-M. Lee et al., Solid. State. Electron., 53 (2009) 1116-1125