This paper presents the low cost electrodeposition of a transparent and conductive chlorine doped ZnO layer with performances comparable to that produced by standard vacuum processes. First, an in-depth study of the defect physics by ab-initio calculation shows that chlorine is one of the best candidates to dope the ZnO. This result is experimentally confirmed by a complete optical analysis of the ZnO layer deposited in a chloride rich solution. We demonstrate that high doping levels (>1020 cm−3) and mobilities (up to 20 cm2 V−1 s−1) can be reached by insertion of chlorine in the lattice. The process developed in this study has been applied on a CdS/Cu(In,Ga)(Se,S)2 p-n junction produced in a pilot line by a non vacuum process, to be tested as solar cell front contact deposition method. As a result efficiency of 14.3% has been reached opening the way of atmospheric production of Cu(In,Ga)(Se,S)2 solar cell.

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 × 10 20 cm −3 and 19 cm 2 •V −1 •s −1 , respectively.

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