UNS: Defect Engineering in Zinc-Blende-Type Absorbers

UNS：闪锌矿型吸收器的缺陷工程

• 批准号: 1511737
• 负责人: David Mitzi
• 金额: $ 29.98万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1511737&HistoricalAwards=false
• 关键词: UNS; Defect; Engineering; Zinc; Blende

PI: David MitziProposal Number: 1511737The sun represents the most abundant potential source of sustainable energy on earth. Solar cells for producing electricity require materials that absorb the sun's energy and convert its photons to electrons, a process called photovoltaics. While solar cells made from crystalline silicon currently have about 90 percent of the worldwide solar photovoltaics (PV) market, alternative solar cells made from very thin layers of non-silicon materials abundant in the earth's crust offer a number of advantages. These include dramatically reduced materials consumption and low-cost fabrication, as well as new form factors that are flexible or foldable, ultralight in weight, and enable facile integration into building structures. Unfortunately, new materials based on elements abundant in the earth's crust cannot match the sunlight-to-electric power conversion efficiency of rigid crystalline silicon-based materials, and so are presently not competitive. This project seeks to gain fundamental understanding of the power conversion performance one promising class of thin-film photovoltaic materials based on zinc blends, which are made from a mixture of nontoxic elements abundant in the earth's crust and are relatively inexpensive. The research will focus on controlling the atomic level disorder within these materials to ultimately provide a viable pathway to low-cost, scalable, high-performance solar photovoltaics. The research will also engage and train a new generation of undergraduate, graduate and postdoctoral scientists in the important area of sustainable energy materials development. Results from the research will also be incorporated into undergraduate and graduate level materials science courses at Duke University. Current thin film solar photovoltaic materials in commercial use, including CIGS and Cd-Te based materials, contain elements that are either costly or rare in the earth's crust (e.g., indium, tellurium) or present toxicity issues (e.g., cadmium). These sustainability issues potentially impose limits on future cost reduction and market share. Recently, kesterite-based thin-film solar cells made of (Cu)2-ZnSn-(S,Se)4-(CZTSSe), in which indium/gallium in CIGS-Se materials are replaced by more readily available and lower-cost elements zinc/tin, have achieved conversion efficiencies of up to 12.6%. However, this efficiency is still only about one-half that of the best crystalline silicon or thin-film commercial solar PV materials. The proposed research is based on the hypothesis that anti-site structural disorder in current zinc-blende material matrices (e.g., Cu on Zn, Zn on Cu) lead to electrical potential energy fluctuations and band tailing that effectively limits the open-circuit voltage. The overall goals of this research are to understand the nature of anti-site disorder in copper chalcogenide based zinc-blende materials for solar PV, and to design new blende materials in which the level of anti-site disorder can be controlled and reduced through a combination of rational computational and experimental materials design approaches. The research plan has three objectives. The first objective is to computationally evaluate prospective zinc-blende-related materials for PV absorbers, focusing on identifying the materials features that lead to more benign recombination-based defects and grain boundaries. The second objective is to design and synthesize stable CZTSSe analogs that have a lower propensity towards anti-site disorder and band tailing. Finally, the third objective is to study the impact of varying amounts of anti-site disorder on materials and their device properties. Achievement of the project goals will provide a framework for understanding defect control in complex energy harvesting materials and offer one pathway to new scalable and high-efficiency solar PV devices.

PI：David Mitzi 提案编号：1511737 太阳是地球上最丰富的潜在可持续能源。 用于发电的太阳能电池需要吸收太阳能量并将其光子转化为电子的材料，这一过程称为光伏发电。 虽然由晶体硅制成的太阳能电池目前占据全球太阳能光伏 (PV) 市场约 90% 的份额，但由地壳中丰富的非硅材料的非常薄层制成的替代太阳能电池具有许多优势。 其中包括大幅减少材料消耗和低成本制造，以及灵活或可折叠、重量超轻且能够轻松集成到建筑结构中的新外形。 不幸的是，基于地壳中丰富元素的新材料无法与刚性晶体硅基材料的太阳光到电能的转换效率相媲美，因此目前不具有竞争力。该项目旨在从根本上了解电力转换性能，这是一类基于锌混合物的有前景的薄膜光伏材料，这种材料由地壳中丰富的无毒元素的混合物制成，并且相对便宜。 该研究将集中于控制这些材料内的原子级无序，最终为低成本、可扩展、高性能的太阳能光伏发电提供一条可行的途径。该研究还将吸引和培训可持续能源材料开发重要领域的新一代本科生、研究生和博士后科学家。 研究结果还将被纳入杜克大学本科和研究生材料科学课程。 目前商业用途的薄膜太阳能光伏材料，包括 CIGS 和 Cd-Te 基材料，含有昂贵或地壳中稀有的元素（例如，铟、碲）或存在毒性问题（例如，镉）。 这些可持续性问题可能会限制未来的成本降低和市场份额。 最近，由(Cu)2-ZnSn-(S,Se)4-(CZTSSe)制成的基于锌黄锡矿的薄膜太阳能电池，其中CIGS-Se材料中的铟/镓被更容易获得和更低成本的锌/锡元素取代，已实现高达12.6%的转换效率。然而，这种效率仍然仅为最好的晶体硅或薄膜商业太阳能光伏材料的一半左右。该研究基于这样的假设：当前闪锌矿材料基体（例如，Cu on Zn、Zn on Cu）中的反位结构无序会导致电势能波动和能带拖尾，从而有效限制开路电压。本研究的总体目标是了解太阳能光伏用铜硫族化物基闪锌矿材料中反位点无序的本质，并设计新的闪锌矿材料，通过合理的计算和实验材料设计方法相结合，可以控制和降低反位点无序水平。该研究计划有三个目标。 第一个目标是通过计算评估用于光伏吸收器的预期闪锌矿相关材料，重点是识别导致更良性的基于重组的缺陷和晶界的材料特征。 第二个目标是设计和合成稳定的 CZTSSe 类似物，其反位点无序和带拖尾的倾向较低。 最后，第三个目标是研究不同数量的反位点无序对材料及其器件性能的影响。该项目目标的实现将为理解复杂能量收集材料的缺陷控制提供一个框架，并为新型可扩展和高效太阳能光伏设备提供一条途径。