Control of Optical Properties of Surfaces for Improved Solar Thermophotovoltaic Systems

Alternative energy systems are crucial to meeting the expanding energy needs of the modern world. Unfortunately, the wide spectrum of solar radiation greatly limits the efficiency of photovoltaic systems. Solar thermophotovoltaic (STPV) technology overcomes this problem by tailoring the spectrum of incoming light to better match a photovoltaic cell. This has the potential to greatly increase the efficiency of photovoltaic systems and to help meet future energy demands in an environmentally friendly way.

The main challenge in designing efficient STPV systems is controlling the optical properties of the system's light absorbing and emitting surfaces. Through the use of nanostructures, the level of optical control needed to make highly efficient STPV systems will be realized. This work presents a study of the effects of various microscale and nanoscale structures on the absorption and emission spectra of surfaces, as well as their direct application in STPV systems. Computer modeling is used to determine the absorption spectra of various nanostructured surfaces and to predict the efficiency gains from using these structures in an STPV system. The ability to economically fabricate structures for large-area systems is also discussed.

A design for a full STPV system utilizing nanostructures for improved efficiency is presented, and the losses in such a system are analyzed. The system is then fabricated, and device performance is compared with simulation. A path towards future improvement of STPV systems is discussed. Additionally, a close collaboration was established with the Center for Nanophase Materials (CNM) at Argonne National Laboratory (ANL), leading to several joint research publications and access to modeling computers and fabrication facilities.