Chemical incorporation of copper into indium selenide thin-films for processing of CuInSe2 solar cells

• Published in: Progress in photovoltaics Vol. 16; no. 7; pp. 585 - 593
• Main Authors: Hibberd, C. J., Ernits, K., Kaelin, M., Müller, U., Tiwari, A. N.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.11.2008; Wiley
• Subjects: Applied sciences; CuInSe2; Energy; Exact sciences and technology; ion-exchange; low-cost; Natural energy; non-vacuum; Photovoltaic conversion; photovoltaics; selenization; Solar cells. Photoelectrochemical cells; Solar energy; Measurement; non-vacuum; Scanning electron microscopy; Costs; Chemical method; CuInSe2; low-cost; Rough surface; selenization; Thin film; Copper Indium Selenides; Solar cell; Crystalline material; Chalcopyrite; Thin film cell; Photoelectron spectrometry; X ray diffractometry; Microstructure; ion-exchange; photovoltaics
• ISSN: 1062-7995; 1099-159X
• DOI: 10.1002/pip.843

A chemical method of incorporating copper into indium selenide thin‐films has been investigated, with the goal of creating a precursor structure for conversion into CuInSe2 (CIS) layers suitable for solar cell processing. The precursor and converted layers have been investigated with scanning electron microscopy (SEM), X‐ray diffraction (XRD), Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS). From these measurements, the incorporation of copper into the indium selenide layers is concluded to proceed by an ion‐exchange reaction. This reaction results in the formation of a precursor layer with a graded compositional depth‐profile containing the crystalline phases In2Se3 and Cu2−xSe. Selenisation of the precursor layer homogenises the composition and forms chalcopyrite CIS. These CIS layers exhibit a dense microstructure with rough surface morphology, which is ascribed to a non‐optimal selenisation process. Solar cells with the structure ZnO: Al/i‐ZnO/CdS/CIS/Mo/glass have been processed from the selenised layers and have exhibited efficiencies of up to 4% under simulated AM1·5 illumination. Copyright © 2008 John Wiley & Sons, Ltd.