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Title:Assembly and light management of solar microcells for concentration photovoltaics
Author(s):He, Junwen
Director of Research:Nuzzo, Ralph G.
Doctoral Committee Chair(s):Nuzzo, Ralph G.
Doctoral Committee Member(s):Gewirth, Andrew A.; Murphy, Catherine J.; Braun, Paul V.
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Concentration photovoltaics
III-V solar cells
Abstract:Advances in printing-based assembly technology enable high volume integration of microscale solar cells and afford novel module architectures with attributes not present in conventional concentration photovoltaic (CPV) systems. The work contained in this thesis highlights efforts and design strategies in the use of micro-optical concentrators for improved light management in microcell-based photovoltaic systems. Conventional CPV systems have poor optical efficiencies due to their inability to utilize diffuse sunlight and Fresnel reflection losses from the multiple optical interfaces. The first part of my work addresses these two constraints by 1) integrating form-fitting silicon solar cells on commercial III-V based CPV platforms that enable capture of diffuse sunlight and 2) using wet etching chemistry to prepare outstanding antireflection coatings that greatly suppress Fresnel reflections on highly curved CPV lenses. These efforts provide a viable pathway to achieving “zero-loss” CPV platforms with unprecedented ultrahigh module efficiencies. Unlike conventional CPV systems, use of external optical components to split the solar beam geometrically and redistribute it to an array of subcells that are individually designed and optimized represents a new way forward for full solar spectrum conversion. In this work, I propose a novel spectrum splitting architecture for high concentration photovoltaics based on exploiting the intrinsic dispersion of a lens. The design can simultaneously concentrate and split the solar spectrum with a single point focus lens. Simulations along with experimental measurements on a mechanically stacked InGaP/GaAs dual junction prototype confirms the utility of this approach for ultrahigh optical concentration (>2000X). Instead of using passive geometric optical elements, a luminescent solar concentrator (LSC) provides an alternative means of optical concentration by actively absorbing and re-emitting solar radiation into a planar waveguide via total internal reflection. The last part of this thesis describes design rules and strategies for large-scale integration of InGaP solar microcells for use in a prototype micro-optical tandem LSC PV module. Embedded quantum dots down-convert high energy photons into concentrated luminescence which feeds an integrated InGaP microcell array while a Si cell is used in tandem to convert the low energy photons. Future directions of development on this type of concentrator are discussed and outlined at the end of the thesis to provide a broader perspective on this type of approach.
Issue Date:2018-06-27
Rights Information:Copyright 2018 Junwen He
Date Available in IDEALS:2018-09-27
Date Deposited:2018-08

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