P-Type CuInSe2 Thin Films and Solar Cells Prepared by One-Step Electrodeposition

Abstract

P-type polycrystalline CuInSe2 (CIS) thin films have been deposited on molybdenum coated glass by one-step electrodeposition. Potentiostatic method with a three-electrode cell was used. The composition of the films was controlled by applying different electrode potentials or adjusting the ratio of Se (IV) concentration to the Cu (II) consentration in the solution. Selenization was carried out at 400°C in an elemental selenium atmosphere in a vacuum furnace. The band gap of the films is about 1.02 eV, which was determined from the optical transmission and reflection measurements. An absorption coefficient (α) as high as ~105 cm-1 is obtained at short wavelength (< 700 nm). Near the band edge, α is 104 cm-1. A solar cell structure of Mo/CIS/CdS/ZnO was fabricated. The ZnO layer was deposited by pulsed laser deposition. The initial solar cell showed a Voc of about 130mV with a CIS absorber layer thickness of 0.5 µm. The improvement of the solar cell is under investigation.