Article pubs.acs.org/JPCC
Perchlorate-Induced Doping of Electrodeposited ZnO Films for Optoelectronic Applications Jean Rousset,*,†,§,⊥ Fabien Tsin,†,§ Maxim Guc,‡ Julien Vidal,†,§,⊥ Arthur Le Bris,†,∥ Angélica Thomere,†,∥ Victor Izquierdo-Roca,‡ and Daniel Lincot†,∥,⊥ †
IRDEP, Institute of Research and Development for Photovoltaic Energy, UMR 7174, CNRS-EDF-Chimie ParisTech, 6 quai Watier, 78401 Chatou Cedex, France ‡ Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adria de Besos, Barcelona, Spain § EDF R&D, 6 quai Watier, 78401 Chatou Cedex, France ∥ CNRS, 6 quai Watier, 78401 Chatou Cedex, France ⊥ IPVF, Ile-de-France Photovoltaic Institute, 8 rue de la Renaissance, 92160 Antony, France S Supporting Information *
ABSTRACT: The aim of this work is to produce via a low cost technique a thin film of ZnO showing optoelectronics properties similar to those one could obtain through various vacuum techniques. In order to achieve such goal, electrodeposition appears to be one of the most interesting approaches. Employing such technique in a Cl-containing bath, a high doping of the ZnO layer can be readily achieved through the substitution of a chloride ion for an oxygen atom in the ZnO lattice: the obtained optoelectronic properties are comparable to the ones of vacuum deposited layer. However, the introduction of chloride was found to be difficult to control, leading to a high concentration of inactive chloride in the ZnO lattice and, as a result, lower electrical performances of the material. In this study, the limitation of chloride doping is evidenced and explained considering the formation of chloride rich compounds. Moreover, ab initio calculations demonstrate that incorporation of perchlorate ions in the ZnO lattice at an oxygen site is possible and highlight the efficient doping character of this substitution. Then the influence of the perchlorate ions on the morphological, structural, and optoelectronic properties of electrodeposited ZnO thin films have been experimentally explored. In particular, this study demonstrates that the use of perchlorate as chlorine source prevents the formation of undesirable chlorine rich phases and to reach high doping level and mobility up to 1.7 × 1020 cm−3 and 19 cm2·V−1·s−1, respectively.
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INTRODUCTION Nowadays transparent conductive oxides are key materials in numerous functional applications such as photovoltaic energies, electroluminescence diode, or touchscreens.1 Various studies have focused so far on the development of cost-effective materials and deposition techniques targeting the best balance between transparency and conductivity. The aim of this work is to produce by a low cost technique ZnO thin films showing optoelectronics properties similar to those obtained from materials grown by vacuum techniques such as sputtering. In this context, the electrodeposition of zinc oxide appears to be one of the most interesting approaches.2−4 Indeed, this process combines a material composition that only involves low cost and abundant elements and a well-known atmospheric process deposition carried out in a very simple water-based electrolyte and at low temperature (
