RUI: Printable Metal Contacts to Realize Fully Printable All-Inorganic CdTe Photovoltaics

RUI：可印刷金属触点实现完全可印刷全无机 CdTe 光伏

• 批准号: 2305503
• 负责人: Troy Townsend
• 金额: $ 18.53万
• 依托单位: St Mary's College of Maryland
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2305503&HistoricalAwards=false
• 关键词: RUI; Printable; Metal; Contacts; Realize

Photovoltaic (PV) energy conversion can provide more power than we use globally; however, this renewable energy source still only contributes to 3% of our energy portfolio largely due to the prohibitive cost of material processing via high temperature or vacuum-based deposition. In response to this, a variety of low cost and rapid Roll-to-Roll (R2R) printing techniques that were invented for printing media are now being revived and adapted to deposit nanoscale electronic inks to build lightweight and flexible electronic devices at rapid production speeds. Solid state PV devices are deposited layer-by-layer and contain semiconducting light absorbing materials sandwiched between two metal contacts. The chemical composition and processing conditions of each layer can be tuned to adjust the device properties, which are dramatically affected by the alignment of the electron energy levels at the interfaces between layers. As charge flows through the device circuit, noble metal contacts with low electron energies are chosen for the anode whereas reactive metals make suitable contact at the cathode.¬¬ Energy mismatch between the light harvesting semiconductor and the metal contact can lead to significant loss of generated charge and restrict device performance. Despite this, printable metals are currently limited to nanomaterials of gold, silver and carbon, and printable cathode metals are absent from the literature because of the air-sensitivity of their precursor inks. This proposed study addresses the need for low-cost printable anode me¬¬tal alternatives and novel printable cathode electrodes to achieve higher efficiency devices at a fraction of the cost of conventional PV. Additionally, this research will demonstrate the first fully printed all-inorganic PV devices including optimization through composition and interface engineering of the printable materials and their interfaces. This project will be conducted at a primarily undergraduate institution and will provide nanoscience research experience opportunities for underrepresented groups while preparing students for materials science career pathways. Undergraduate research students will also participate in public outreach chemistry demonstrations with local schools and STEM camps. This project directly addresses a major limitation in the field of printable electronics by investigating printable metal contacts with a specific focus on high throughput Roll-to-Roll (R2R) production of low-cost solar photovoltaics (PV). The electronic properties of metal contacts have a major influence on band bending, and this dramatically affects device efficiency. Specifically for solution processed CdTe/ZnO nanocrystal PV, high work function and low work function metals are required to make ohmic contact with p-type CdTe and n-type ZnO, respectively. Currently, however, demonstrated printable high work function metals are limited to nanoparticles of silver, gold and carbon, and printable low work function metals are absent from the literature due to the air-sensitivity of their precursor inks. For this reason, researchers investigating printable PV materials typically start with vacuum-deposited ITO for the bottom contact, despite Fermi level pinning with the p-type material in the case of CdTe, followed by vacuum-deposited aluminum on the n-type layer for the top contact. To address the discrepancy between pairing low cost R2R compatible ink-based materials with size/speed restricted vacuum-based contacts, we will use composition and interface engineering of transparent and opaque printable low and high work function contacts to realize and optimize fully printed robust all-inorganic CdTe PV devices. Changes in work function will be measured with a Kelvin Probe, and printed films will be characterized with UV/Vis and X-ray fluorescence spectroscopy, Hall effect measurements, atomic force microscopy and X-ray diffraction. Completed devices will be printed with research grade InkJet and R2R compatible rotogravure printers followed by 1 sun illumination measurements. Applying these engineered materials to printed CdTe PV will uncover their effects on band energy alignments and their resulting device properties to advance the field of printable electronics.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.

光伏（PV）能源转换可以提供比我们全球使用的更多的电力;然而，这种可再生能源仍然只占我们能源组合的3%，这主要是由于通过高温或真空沉积进行材料加工的成本过高。响应于此，发明用于印刷介质的各种低成本和快速卷对卷（R2 R）印刷技术现在正在复兴并适于存款纳米级电子油墨以快速生产速度构建轻质和柔性电子器件。固态PV器件是逐层沉积的，并且包含夹在两个金属触点之间的半导体光吸收材料。每层的化学组成和处理条件可以被调整以调整器件特性，器件特性受到层之间界面处电子能级的对准的显著影响。当电荷流过器件电路时，具有低电子能量的贵金属触点被选择用于阳极，而活性金属在阴极处形成合适的触点。光捕获半导体和金属触点之间的能量失配可能导致所产生的电荷的显著损失并限制器件性能。尽管如此，可印刷的金属目前仅限于金、银和碳的纳米材料，并且可印刷的阴极金属由于其前体油墨的空气敏感性而不存在于文献中。该提出的研究解决了对低成本可印刷阳极金属替代物和新型可印刷阴极电极的需求，以在传统PV的成本的一小部分下实现更高效率的器件。此外，这项研究将展示第一个完全印刷的全无机光伏器件，包括通过可印刷材料及其界面的组成和界面工程进行优化。该项目将在一个主要的本科院校进行，并将为代表性不足的群体提供纳米科学研究经验的机会，同时为学生准备材料科学职业道路。本科研究生还将参加与当地学校和STEM营地的公共外展化学演示。该项目通过研究可印刷金属触点直接解决了可印刷电子领域的主要限制，特别关注低成本太阳能光伏（PV）的高吞吐量卷对卷（R2 R）生产。金属接触的电子性质对能带弯曲有重要影响，这会显著影响器件效率。具体地，对于溶液处理的CdTe/ZnO异质结光伏，需要高功函数和低功函数金属分别与p型CdTe和n型ZnO形成欧姆接触。然而，目前，所证明的可印刷的高功函数金属限于银、金和碳的纳米颗粒，并且可印刷的低功函数金属由于其前体油墨的空气敏感性而不存在于文献中。出于这个原因，研究可印刷PV材料的研究人员通常从底部接触的真空沉积ITO开始，尽管在CdTe的情况下，费米能级与p型材料钉扎，然后在顶部接触的n型层上真空沉积铝。为了解决低成本R2 R兼容墨水基材料与尺寸/速度受限的真空基接触件配对之间的差异，我们将使用透明和不透明的可印刷低功函数和高功函数接触件的组成和界面工程来实现和优化完全印刷的坚固的全无机CdTe PV器件。功函数的变化将用开尔文探针测量，印刷膜将用UV/维斯和X射线荧光光谱、霍尔效应测量、原子力显微镜和X射线衍射表征。完成的器械将使用研究级喷墨和R2 R兼容轮转凹版印刷机进行印刷，然后进行1次阳光照射测量。将这些工程材料应用于印刷CdTe PV将揭示它们对能带能量排列的影响及其产生的器件特性，以推动可印刷电子领域的发展。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。