Optimizing performance of chemically passivated carrier selective PEDOT: PSS based heterojunction solar cells
Date
2017
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Publisher
University of Delaware
Abstract
With today’s photovoltaic technology we would require about 10,000 square miles of solar panels—an area the size of New Hampshire and Rhode Island combined to completely meet the country’s energy demand [1]. Solar must be financially competitive to compete with other renewable energies and replace the conventional finite resources. There is constant effort to establish a solar technology which can achieve high power efficiencies with lower manufacturing costs. The most dominant solar technology is crystalline silicon which constitutes more than 90% of the solar market [2]. It has high proven efficiencies and the potential to rise to higher efficiencies with lower processing costs. Commercial scale crystalline silicon solar cells are based on aluminum back surface(AL-BSF) or passivated rear emitter contact (PERC) cell technologies that rely on high temperature processing. High temperature processing despite the most adopted process has few challenges like high capital expenditure(CAPEX) and operating costs(OPEX) of the tools, inability to process thin wafers easily and silicon impurities getting activated during the high-temperature steps leading to reduced minority carrier lifetimes and higher losses. ☐ This thesis focusses on an alternative approach to forming silicon based solar cells using heterojunctions with materials that can be deposited at low temperatures. These carrier selective induced junction solar cells demonstrate a heterojunction like solar architecture with an organic polymer, poly(3,4-ethylenedioxythiophene) poly styrene sulfonate (PEDOT PSS), a chemical passivant- benzoquinone(BQ) and crystalline silicon as absorber with aluminum back surface field. These cells are also called hybrid solar cells because they involve the marriage of organics and inorganics. Device optimization of the hybrid solar cells is of interest in this thesis and is largely based off the work previously done at the University of Delaware. Work is aimed at improving the solar cell performances by better cell design and processing techniques. These hybrid cells have demonstrated 10% power efficiencies at lab scale and are comparable to record efficiency hybrid solar cells (~14%). The potential commercial impact of this cell technology has also been discussed in this thesis.
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Keywords
Applied sciences, Carrier selective solar cells, Heterojunction solar cells, Induced junction, PEDOT, PSS