High Voltage Photovoltaic Devices for Autonomous Solar-to-Fuel Applications

In this dissertation, a framework is presented for the development of high voltage multijunction photovoltaic (PV) devices. Specifically, wireless silicon-based monolithically integrated 2-terminal multijuction PV devices are investigated. Such devices can be used in autonomous solar-to-fuel synthesis systems, as well as other innovative approaches in which the multijunction solar cell is used not only as a photovoltaic current-voltage generator, but also as an ion-exchange membrane, electrochemical catalysts and/or optical transmittance filter. The framework presented in this dissertation encompasses all investigations performed in answering this thesis’ central question: To what extent can fundamental insight and device engineering reduce the opto-electrical losses in a hybrid wafer-based and thin film photovoltaic multijunction device, based on group IV elements? The answer to this central question is provided in three parts, focusing on I. textures, photovoltaic materials and single junction solar cells, II. a low bandgap-energy hydrogenated (:H) germanium(tin) (Ge(Sn)) absorber and III. multijunction PV and photoelectrochemical (PEC) devices...