Date of Award

Fall 2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical and Computer Engineering

First Advisor

Mark S. Lundstrom

Second Advisor

Peter A. Bermel

Committee Chair

Mark S. Lundstrom

Committee Co-Chair

Peter A. Bermel

Committee Member 1

Muhammad Ashraful Alam

Committee Member 2

Jeffery Gray

Committee Member 3

Gerhard Klimeck

Abstract

Careful electrical design and optical design are both crucial for achieving high-efficiency solar cells. It is common to link these two aspects serially; the optical design is first done to minimize reflection and maximize light trapping, and then the resulting optical generation rate is input to the electrical simulation. For very high efficiency solar cells that approach the Shockley-Queisser limit, however, electrical and optical transports are tightly coupled in both directions. Photons generated by radiative recombination can be reabsorbed to create additional electron-hole pairs (so-called photon recycling), which decreases losses. A variety of novel photon management schemes are currently being explored. To achieve the promise of these new approaches, a self-consistent simulation framework that rigorously treats both photons and electrons is needed. In this work, the thin-film GaAs solar cell, the single nanowire solar cell, and the GaInP/GaAs tandem solar cell are investigated. For solar cell characterization, this work examines the validity of the reciprocity theorem and quantitative lifetime parameter extraction using Time-Resolved Photoluminescence (TRPL) and Photoluminescence Excitation Spectroscopy (PLE). Overall, this thesis work has created a new simulation tool for advanced photovoltaic devices based on the self-consistent coupling of wave optics with electronic transport, which lead to accurate predictions of the characteristics and performance. Optimization of photon recycling facilitates improved design strategies to approach the Shockley-Queisser limit, which will eventually pave the way for extension to advanced designs, capable of approaching or even exceeding the Shockley-Queisser limit in the future.

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