Photovoltaic Characteristics of Ultra-Thin Single Crystalline Silicon Solar Cells

Abstract

Photovoltaic characteristics of ultra-thin single crystalline Si solar cells with thicknesses ranging from 7.6 to 3.3 nm are presented. While the short-circuit current (ISC) AM1.5 illumination has shown a linear relationship with the volume of the Si layer, a gradual increase in the open-circuit voltage (VOC) with thinner Si layer has been confirmed, implying the bandgap enlargement of the Si layer due to quantum confinement. Spectral response measurement has revealed an increased optical bandgap of 1.3 eV for 3.3-nm-thick Si solar cells, which is wider than that of 7.6-nm-thick Si ones. Although some process related issues have become clear during the fabrication of solar cells, they can be utilized as top cells for tandem configurations, exceeding the limit of the bulk Si solar cells.