Low Cost Solar Cells Based on Cuprous Oxide

Abstract

The worldwide quest for clean and renewable energy sources has encouraged large research activities and developments in the field of solar cells. In recent years, considerable attention has been devoted to the development of low cost energy converting devices. One of the most interesting products of photoelectric researches is the semiconductor cuprous oxide cell. As a solar cell material, cuprous oxide -Cu2O, has the advantages of low cost and great availability. The potential for Cu2O using in semiconducting devices has been recognized since, at least, 1920. Interest in Cu2O revived during the mid seventies in the photovoltaic community (Olsen et al.,1982). Several primary characteristics of Cu2O make it potential material for use in thin film solar cells: its non-toxic nature, a theoretical solar efficiency of about 9-11%, an abundance of copper and the simple and inexpensive process for semiconductor layer formation. Therefore, it is one of the most inexpensive and available semiconductor materials for solar cells. In addition to everything else, cuprous oxide has a band gap of 2.0 eV which is within the acceptable range for solar energy conversion, because all semiconductors with band gap between 1 eV and 2 eV are favorable material for photovoltaic cells (Rai, 1988). A variety of techniques exist for preparing Cu2O films on copper or other conducting substrates such as thermal, anodic and chemical oxidation and reactive sputtering. Particularly attractive, however, is the electrodeposition method because of its economy and simplicity for deposition either on metal substrates or on transparent conducting glass slides coated with highly conducting semiconductors, such as indium tin oxide (ITO), SnO2, In2O3 etc. This offers the possibility of making back wall or front wall cells as well. We have to note that electrochemical preparation of cuprous oxide (Cu2O) thin films has reached considerable attention during the last years. Electrodeposition method of Cu2O was first developed by Stareck (Stareck, 1937). It has been described by Rakhshani (Jayanetti & Dharmadasa, 1996, Mukhopadhyay et al.,1992, Rakhshani et al.1987, Rakhshani et al., 1996). In this work, a method of simple processes of electrolysis has been applied. Electrochemical deposition technique is an simple, versatile and convenient method for producing large area devices. Low temperature growth and the possibility to control film thickness, morphology and composition by readily adjusting the electrical parameters, as well as the composition of the electrolytic solution, make it more attractive. At present,