CAREER: Transparent, passivating, and carrier-selective heterojunction contacts for silicon and cadmium telluride solar cells

职业：用于硅和碲化镉太阳能电池的透明、钝化和载流子选择性异质结接触

• 批准号: 1846685
• 负责人: Zachary Holman
• 金额: $ 50万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1846685&HistoricalAwards=false
• 关键词: CAREER; Transparent; passivating; carrier; selective

Nontechnical:This CAREER project aims to increase the efficiency of conversion of sunlight into electricity by solar cells. The project will explore the materials science and physics of electrical contacts to solar cells. In so doing, it will advance the understanding of how these contacts limit the operation of the cells. Every solar cell must perform two processes: convert light into excited electrons and extract those electrons in the form of current. The former process is performed by a semiconductor absorber material; the latter by two electrical contacts between which the absorber is sandwiched. Although solar cells are mass manufactured and now generate 1% of the electricity consumed in the U.S., there are still fundamental questions that are unanswered. The research community does not yet understand which properties determine if a material will make an excellent electrical contact and how to quickly find and make materials with the desired properties. This project will provide answers to these questions with a combination of measurements and simulations applied to existing model systems, as well as experiments to use the resulting understanding to develop new contacts. Success in the project will lay the groundwork for solar cells that are 10-15% more efficient than today's cells, reducing the cost of solar electricity generation to below 3 cents per kilowatt-hour. This, in turn, is predicted to accelerate the deployment of solar energy, resulting in 17% of U.S. electricity being generated by solar in 2030 instead of the 5% projected in a business-as-usual scenario. In addition to these scientific, environmental, and societal impacts, this project will also train community college, undergraduate, and graduate students for the 260,000 solar jobs presently in the US through a week-long, hands-on "Solar Cell 101" course in which they make cells and modules from start to finish.Technical:Many photovoltaic (PV) technologies have arrived at absorber materials that have low non-radiative recombination rates and thus could support cell voltages approaching the detailed-balance limit, but no technology has developed comparatively ideal electrical contacts that are transparent, that passivate the absorber surface, and that selectively extract electrons or holes from the absorber. This project targets key questions that inhibit rapid progress in heterojunction contact understanding and technology using (1) a characterization suite that links together the properties of carrier-selective layers, contacts containing those layers, and PV cells containing those contacts, and (2) a new deposition technique using dry-cluster spraying to enable intimate control of the stoichiometry of contact layers without sputter damage. These two platforms will be applied to crystalline silicon and cadmium telluride PV cells as model systems, as these technologies have readily available high-quality absorbers (which makes interpretation of the function of the contacts more apparent), a collection of previously developed contacts for these materials is available for analysis but ideal contacts have yet to be discovered, and any advances in understanding and technology resulting from the project will have large research and commercial impact. After studying the underlying physics of state-of-the-art existing contacts, the project will progress to depositing and testing heretofore unexplored carrier-selective layers, including wide-bandgap, heavily doped, amorphous or polycrystalline III-V materials. This research will address the critical impediment--excellent contacts--to 27%-efficient silicon PV cells and 25%-efficient cadmium telluride cells.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术性：该职业项目旨在提高太阳能电池将阳光转化为电能的效率。该项目将探索太阳能电池电接触的材料科学和物理学。这样做将加深人们对这些接触如何限制电池运行的理解。每个太阳能电池必须执行两个过程：将光转换为激发电子并以电流形式提取这些电子。前一种工艺是通过半导体吸收材料进行的；后者由两个电触点组成，吸收器夹在其间。尽管太阳能电池已实现大规模生产，目前发电量占美国电力消耗的 1%，但仍有一些基本问题尚未得到解答。研究界尚不了解哪些特性决定材料是否能够形成良好的电接触，以及如何快速找到和制造具有所需特性的材料。该项目将通过应用于现有模型系统的测量和模拟相结合，以及利用由此产生的理解来开发新接触的实验来回答这些问题。该项目的成功将为太阳能电池的效率比现在的电池提高10-15%奠定基础，从而将太阳能发电的成本降低到每千瓦时3美分以下。预计这反过来将加速太阳能的部署，到 2030 年美国将有 17% 的电力由太阳能发电，而不是照常情景下预计的 5%。除了这些科学、环境和社会影响之外，该项目还将通过为期一周的实践“太阳能电池 101”课程，为美国目前 260,000 个太阳能工作岗位培训社区学院、本科生和研究生，在该课程中，他们将从头到尾制作电池和模块。 技术：许多光伏 (PV) 技术已经实现了非辐射复合率较低的吸收材料，因此可以 支持电池电压接近详细平衡极限，但没有技术开发出相对理想的透明电接触，钝化吸收器表面，并选择性地从吸收器提取电子或空穴。该项目针对阻碍异质结接触理解和技术快速进步的关键问题，使用（1）将载流子选择性层、包含这些层的接触以及包含这些接触的光伏电池的特性联系在一起的表征套件，以及（2）使用干簇喷涂的新沉积技术，能够在不溅射损坏的情况下密切控制接触层的化学计量。这两个平台将应用于晶体硅和碲化镉光伏电池作为模型系统，因为这些技术具有现成的高质量吸收器（这使得对触点功能的解释更加明显），先前开发的这些材料的触点集合可用于分析，但尚未发现理想的触点，并且该项目带来的理解和技术方面的任何进步都将产生巨大的研究和商业影响。在研究了最先进的现有接触的基础物理原理之后，该项目将继续沉积和测试迄今为止尚未探索的载流子选择性层，包括宽带隙、重掺杂、非晶或多晶 III-V 材料。这项研究将解决 27% 效率的硅光伏电池和 25% 效率的碲化镉电池的关键障碍——良好的接触。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Understanding what limits the voltage of polycrystalline CdSeTe solar cells

• DOI: 10.1038/s41560-022-00985-z
• 发表时间: 2022-03-03
• 期刊: NATURE ENERGY
• 影响因子: 56.7
• 作者: Onno, Arthur;Reich, Carey;Holman, Zachary C.
• 通讯作者: Holman, Zachary C.

Passivation, conductivity, and selectivity in solar cell contacts: Concepts and simulations based on a unified partial-resistances framework

• DOI: 10.1063/1.5117201
• 发表时间: 2019-11
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: A. Onno;Christopher Chen;Priyaranga Koswatta;M. Boccard;Z. Holman

Overcoming Redox Reactions at Perovskite-Nickel Oxide Interfaces to Boost Voltages in Perovskite Solar Cells

• DOI: 10.1016/j.joule.2020.06.004
• 发表时间: 2020-08-19
• 期刊: JOULE
• 影响因子: 39.8
• 作者: Boyd, Caleb C.;Shallcross, R. Clayton;McGehee, Michael D.
• 通讯作者: McGehee, Michael D.