Reversible, Light Induced Changes in a-Si:H Films and Solar Cells

Abstract

Continuous progress is being made in the conversion efficiencies of a- Si:H solar cells and efficiencies in excess of 11% have been achieved. Because of these advances and the development of a-Si:H cell technologies there is an increased interest in the long term performance of a-Si:H cells and the mechanisms responsible for their degradation. The reversible light-induced changes in a-Si:H solar cells are generally associated with the Staebler-Wronski effect (SWE) (1). This effect has been studied on a wide range of a-Si:H materials using a variety of different experimental techniques and this talk reviews the results that have been obtained on a- Si:H films and solar cells (2). It discusses in greater detail recent studies on a-Si:H solar cell structures in which simultanous measurements have been made on the changes in both the photovoltaic properties as well as their electronic properties and densities of gap states. In particular it focuses on several results obtained with semitransparent metal-undoped a-Si:H Schottky barrier solar cell structures (3).