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提议编号：1511737太阳代表着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，这一过程被称为光伏。虽然由晶硅制成的太阳能电池目前占据了全球太阳能光伏(PV)市场约90%的份额，但由地壳中丰富的非常薄的非硅材料制成的替代太阳能电池提供了许多优势。其中包括显著降低材料消耗和低成本制造，以及灵活或可折叠、重量超轻并可轻松集成到建筑结构中的新外形因素。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能到电能的转换效率相提并论，因此目前没有竞争力。该项目旨在从根本上了解太阳能电池的电能转换性能，这是一种基于锌混合物的很有前途的薄膜光伏材料，锌混合物是由地壳中丰富的无毒元素混合物制成的，相对便宜。这项研究将专注于控制这些材料中的原子能级无序，最终为低成本、可扩展、高性能的太阳能光伏提供一条可行的途径。这项研究还将在可持续能源材料开发的重要领域吸引和培训新一代本科生、研究生和博士后科学家。这项研究的结果也将被纳入杜克大学的本科生和研究生水平的材料科学课程。目前商业使用的薄膜太阳能光伏材料，包括基于CIGS和Cd-Te的材料，含有地壳中昂贵或稀有的元素(如铟、碲)或存在毒性问题(如镉)。这些可持续性问题可能会对未来的成本降低和市场份额造成限制。最近，用更易获得、成本更低的锌/锡元素取代CaGS-Se材料中的铟/镓的(Cu)2-ZnSn2-(S，Se)4-(CZTSSe)制成的凯斯特石基薄膜太阳电池，转换效率高达12.6%。然而，这种效率仍然只有最好的晶硅或薄膜商业太阳能光伏材料的一半左右。目前闪锌矿材料中的反位结构无序(例如，铜在锌上，锌在铜上)会导致电势能起伏和带尾，从而有效地限制了开路电压。本研究的总体目标是了解太阳能光伏用铜硫化物基闪锌矿材料中反位无序的本质，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来控制和减少反位无序的水平。该研究计划有三个目标。第一个目标是计算评估未来的闪锌矿相关光伏吸收材料，重点确定导致更良性的基于复合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，具有较低的抗部位紊乱和条带拖尾倾向。最后，第三个目标是研究不同数量的反位无序对材料及其器件性能的影响。项目目标的实现将为理解复杂能源收集材料中的缺陷控制提供一个框架，并为开发新的可扩展和高效的太阳能光伏设备提供一条途径。