Modeling the Charge Transport of Nanowire-based Dye-Sensitized Solar Cells

传统的基于纳米颗粒薄膜的染料敏化太阳能电池（DSSCs）的效率受到电子注入和界面电荷重组和反反应损失机制之间的竞争的限制。如果没有局部场驱动电子到电流收集器，界面电子可以与光活性染料重新结合或与电解质反反应。这些不良损耗限制了光阳极的厚度和最大转换效率。纳米线阵列是一种很有前途的结构，由于电场的作用，它改善了电子传输和电荷注入。然而，基于纳米线的光电阳极的DSSC器件到目前为止还不能充分利用纳米线在电子传输、短路电流和开路电压方面的优势。本提案的目的是开发一个模型来模拟基于纳米线的DSSCs的性能，以便能够更有效地理解和使用这些器件中的场辅助电荷传输效应。本研究的重点是将考虑界面电场的电荷输运模型与实验研究相结合，以验证基于纳米线的DSSCs的输运动力学和转换效率。采用阳极氧化铝模板法制备半导体氧化物纳米线，在制备不同材料类型、宽高比和间距的纳米线方面具有很大的灵活性。这种灵活性允许系统地研究场辅助电子输运对DSSC效率的影响。开发的模型可用于确定制造参数（即纳米线直径，壳厚度，长度和阵列密度），以最大化效率。这些结果也可能为DSSCs控制电荷传输的关键反应或过程提供新的见解。除了光伏应用外，纳米线阵列的发展对电子、光电、环境和生物医学应用也很重要。拟议的教育和推广活动利用佛罗里达大学（UF）现有的成功项目。佛罗里达大学之前通过美国国家科学基金会CCLI（课程、课程和实验室改进）拨款开发的纳米技术工程课程序列将被加强，包括太阳能光伏。佛罗里达大学学者计划将为本科生提供参与拟议研究的机会。来自弱势群体的学生将通过与PI在拟议研究背景下的互动，接受UF大学少数民族指导计划的指导。佛罗里达大学教师学者计划将为学校教师提供有关可再生能源和纳米材料的短期课程。高中学生将通过佛罗里达大学学生科学培训计划招收暑期体验。

1033736ZieglerIntellectual MeritEfficiencies of traditional dye-sensitized solar cells (DSSCs) based on nanoparticle thin films are limited by the competition between electron injection and the loss mechanisms from interfacial charge recombination and back reactions. Without a localized field driving electrons to the current collector, interfacial electrons can recombine with the photoactive dye or back-react with the electrolyte. These undesirable losses limit the photoanode thickness and maximum conversion efficiency. Nanowire arrays are promising architectures that have improved electron transport and charge injection due to an electric field. However, DSSC devices based on nanowire-based photoanodes thus far have not been able to take full advantage of the benefits that nanowires offer to electron transport, short circuit current, and open circuit voltage. The objective of this proposal is to develop a model that simulates the performance of nanowire-based DSSCs so that field-assisted charge transport effects within these devices can be understood and used more effectively. The proposed work will focus on combining a charge transport model which accounts for the interfacial electric field with experimental studies to validate the transport dynamics and conversion efficiencies calculated for nanowire-based DSSCs. The anodic-alumina-oxide templating approach used to fabricate the semiconductor oxide nanowires takes advantage of the great flexibility in preparing nanowires with different types of materials, aspect ratios, and spacing. This flexibility allows the systematic study of the effect of field-assisted electron transport on DSSC efficiency. The developed model can be used to determine the fabrication parameters (i.e. nanowire diameter, shell thickness, length, and array density) required to maximize efficiency. These results may also provide new insight into the controlling key reactions or processes in charge transport for DSSCs.Broader ImpactsBeyond photovoltaic applications, the development of nanowire arrays is important to electronic, optoelectronic, environmental, and biomedical applications. The proposed education and outreach activities leverage existing successful programs at the University of Florida (UF). An engineering course sequence in nanotechnology developed through previous a NSF CCLI (Course, Curriculum, and Laboratory Improvement) grant at UF will be enhanced to include solar photovoltaics. Opportunities for undergraduates to participate in the proposed research will be provided through the UF University Scholars Program. Students from under-represented groups will be mentored UF University Minority Mentoring Program through interactions with the PI in the context of the proposed research. Short courses for school teachers on renewable energy and nanomaterials will be offered through the UF Teachers as Scholars Program. High school students will be recruited for summer experiences through the UF Student Science Training Program.