High-Voltage GaAs Photovoltaic Laser Power Converters

The main drawback of photovoltaic (PV) laser power converters based on GaAs material is the low output voltage, which is often insufficient to power electronic circuits directly. Aside from the use of a dc-dc converter in combination with a single PV converter, it is possible to boost the voltage by the monolithic serial interconnection of several converter segments on a single chip, often called multiple converters. Another novel approach introduced in this paper is a multijunction PV cell, where several subcells of the same material are stacked onto a substrate and interconnected by interband tunnel diodes. This paper explores a tandem GaAs-GaAs converter and compares the results with a 2-V multiple PV converter under monochromatic laser illumination. In addition, 4-V multiple PV converters with maximum monochromatic efficiencies (810 nm) of up to 50.1% at 51.6 W/cm(2) and 6-V converters are investigated. Thereby, the fabrication technology of the devices is outlined and the influence of inhomogeneous illumination on the performance of these energy converters is discussed.