Glass photonics meets photovoltaics: general principles and a case study

Abstract

In this study, we present a promising combination of glass photonics and photovoltaics to develop more efficient types of solar cells. Following up on earlier suggestions, we demonstrate that fundamental losses due to the intrinsic spectral mismatch of many photovoltaic devices can be ameliorated using spectral conversion based on rare-earth-doped glass layers. Our goal is to show work in progress in this field by approaching the topic in two ways: First, we will give a brief introduction to the basic concepts of photovoltaic devices and their intrinsic losses. Within this standard conceptual framework, we suggest that gains in efficiency due to spectral conversion layers can be described by an alternative model of absorbing and emitting solar cells, which is based on radiative transfer. Second, we practically demonstrate spectral conversion in a real device, which combines Tb-doped ZnO thin films with a typical organic solar cell. To this end, we describe in detail the fabrication of such a device using RF sputtering, carry out a typical characterization of the glass layer using Raman spectroscopy and analyze the performance of the final device.