Research Projects

Enhanced single-junction efficiencies with front and back reflector architectures

High-efficiency single-junction solar cells are limited by recombination losses that lower Voc. Adding back reflectors to the back of the cell can enhance Voc by enhacning the effective path length of photons while also improving radiative emission from the cell at open-circuit. This design has led to the record efficiency gains in GaAs. Designing a suitable front reflector can further enhance these efficiency gains by more than 8% in GaAs and 2% in Si by limiting blackbody emission from the cell, effectively concentrating light, assuming a perfect back reflector.

Presented at IEEE PVSC (2019)

Semiconductor Upconverters for High-efficiency Photovoltaics

State-of-the-art upconverter materials are currently advancing technologies in medicine and energy, from triggering drug delivery with NIR light to improving solar cell efficiencies. However, further upconverter-backed solar cell performance enhancements are limited by the upconverter material’s absorption bandwidth. Dissertation work demonstrated the first instance of pure-cw sequential, two-photon upconversion. Experiments then focused on design and characterization of colloidal, semiconductor, core/rod/dot nanostructures using time-resolved spectroscopy and quantum yield measurements, with improvements in upconversion efficiency of two orders of magnitude with the addition of a graded rod. Upconversion to photoluminescence quantum yield ratios of 3% were measured.

Published in ACS Nano (2018) and IEEE JPV (2018)

Dissertation available via ProQUEST.