Regular Article

Elaboration of wide bandgap CIGS on silicon by electrodeposition of stacked metal precursors and sulfur annealing for tandem solar cell applications

¹ Institut Photovoltaïque d’Ile-de-France (IPVF), 18 Boulevard Thomas Gobert, 91120 Palaiseau, France
² Université de Nantes, CNRS, Institut des Matériaux Jean Rouxel, IMN, 2 Chemin de la Houssinière, 44300 Nantes, France
³ Faculté des Sciences d'Orsay, Université Paris Saclay, 15 rue Georges Clémenceau, 91400 Orsay cedex, France
⁴ CNRS UMR 9006 IPVF, 18 Boulevard Thomas Gobert, 91120 Palaiseau, France

^* e-mail: alexandre.crossay@cnrs.fr

Received: 25 August 2020
Received in final form: 29 October 2020
Accepted: 30 November 2020
Published online: 15 January 2021

Abstract

A method was developed for the electrodeposition of Cu-In-Ga precursor layers to elaborate Cu(In,Ga)(S,Se)₂ (CIGS) thin films on silicon substrates for future application as silicon/wide-gap CIGS tandem solar cells. An underlayer of Ag was first deposited on silicon substrates to ensure a good adhesion of the electrodeposited stack and to serve as cathode during the deposition process. Cu, In and Ga layers were then sequentially electrodeposited. Ag-Cu-In-Ga precursor layers were finally subjected to elemental sulfur annealing at 600 °C. Formation of compact and adherent AgCIGS is observed. X ray diffraction and photoluminescence analyses confirm the formation of wide-gap CIGS of about 1.6 eV, with a spontaneous gallium grading over the depth of the sample leading to the formation of a bi-layer structure with a gallium rich layer at the interface with silicon.