Investigation of the effect of different back contacts on the growth and efficiency of cigs solar cells

Abstract

Herein, 〖Cu(In〗_(1-x) Ga_(1-x))(〖S,Se)〗_2 films were successfully deposited onto different back contacts: fluorite tin oxide (ITO), Indium doped Tin Oxide (FTO), and Molybdenum Mo by spray pyrolysis technique. The effect of back contacts on the structural and optical properties of CIGS was investigated. The X-ray patterns reveal crystalline phases with preferred phase orientations (112), (220), (220/214), and (312/116) for the different samples and a (110) phase of MoS2, particularly for the molybdenum back contact. SEM showed good crystallinity of the deposit films, especially for CIGS deposited at FTO back contact shows less porosity, homogenous surface, and good crystal size. Optical analyses for different back contacts provided bandgaps of 1.2 eV, 1.4 eV, and 1.64 eV for the films deposited on Mo, FTO, and ITO, respectively. SCAPS-1D simulator was used to exhibit the electrical characteristics of each cell according to the CIGS-deposition results. Among the different back contacts used, Mo showed the best efficiency of 22.93%. For FTO and ITO back contacts, the additional interfacial layer (MoS2 or MoSe2) between the absorber and the back contact shows an improvement in the efficiency from 22.59% to 23,97% and from 13.8% to 14.05%, respectively.