Date of Award

Spring 1-1-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Wounjhang Park

Second Advisor

Sean Shaheen

Third Advisor

Frank Barnes

Fourth Advisor

Garret Moddel

Fifth Advisor

Jao van de Lagemaat

Abstract

An increased need for cheap renewable energy has led to active research in solar technologies with improved efficiency and decreased production cost. Next-generation photovoltaic technologies, which utilize novel materials, processing techniques, and architectures, can improve light absorption and photocurrent generation. Experimental device development suffers from slow troubleshooting timescales, making device simulation a powerful tool for exploration of an ever-increasing parameter space. In this report, we develop and apply a finite element combined optical and electrical device model, which predicts the optoelectronic performance of photovoltaic devices. The model is applied to two systems: the near-infrared absorption enhancement of bulk heterojunction organic photovoltaics, and the effect of light-induced ion migration on the anomalous electrical behavior of organohalide perovskites. In the former, we predict that asymmetry in photogeneration can lead to disparate photocurrents depending on the material properties and device architectures used, and demonstrate experimentally that sub-bandgap absorption enhancement in precise spectral regions predicted by simulation is possible using a plasmonic grating. In the latter, simulations of bias-dependent, vacancy-assisted, and light-modulated halide redistribution on principal bulk device characteristics confirm experimental observations suggesting that light exposure, combined with increased interfacial recombination, is a valid explanation for anomalous electrical behavior in perovskites. We conclude that reduced hysteresis and improved stability in perovskites should be achievable by reducing the density of mobile ionic species.

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