Collaborative Research: Fundamental Studies of Carrier Selective Passivating Contacts for Efficient Photovoltaic Devices using Laser Processing and Atomic Resolution Interfaces

非技术性：太阳能电池将阳光转化为电能，具有几个独特的优势。它们在没有监控的情况下运行，不会排放污染，可以由地球上丰富的无毒材料制成。太阳能的使用正在迅速增长，但它仍然只占发电量的一小部分。为了增加它们在能源市场的份额，必须降低制造和运营太阳能电池的成本，提高太阳能电池的效率。载体选择性钝化触点有望做到这一点。这种触点通过减少太阳能电池层吸收光线的界面和提取电流的金属触点之间的界面处的电损耗来提高电池效率。该项目将使用一种独特的方法来提高对具有这种接触的太阳能电池中损耗机制的基本理解和控制。激光处理提供了一种通过在高速、精细控制的情况下选择性地将激光能量沉积到选定的层中来电激活载流子选择钝化触点的方法。这一过程有可能提高太阳能电池的功率转换效率，同时保持低温和高产量，从而降低每千瓦时产生的能源成本。产生的知识将改进各种类型的太阳能发电以及其他电子和光子设备。该提案汇集了一支经验丰富的多学科团队，他们在太阳能电池制造、激光加工和原子尺度表征方面具有专业知识。PI将广泛接触当地的高中、博物馆和图书馆。通过与太阳能电池制造公司合作，经济影响将被放大。该项目将帮助社会以更少的资源以更低的成本满足未来的能源需求，同时防止污染和气候变化。技术：该项目包括载流子选择钝化接触开发、光伏器件制造、激光加工以及使用透射电子显微镜在原子水平上进行成像。载流子选择钝化接触(CSPC)器件是一种很有前途的新一代光伏器件技术，因为它消除了两种主要的损耗机制：金属与硅的直接接触和掺杂向体相的扩散。对于界面质量、掺杂类型、掺杂激活(和电势扩散)、隧穿机制以及钝化层的作用仍缺乏基本的了解。通过器件建模、制造和激光加工实验，以及透射电子显微镜的研究相结合，将研究CSPC的能带弯曲和带隙的量化程度，热结晶对光吸收的影响，隐含的开路电压和缺陷含量，以及对掺杂激活、结晶、晶体生长和掺杂扩散的独立控制，以使光伏行业更好地了解CSPC，以便采用制造。本研究的创新之处在于，利用脉冲激光加工CSPC，提供了一种只需表面加热即可对器件进行非接触式退火热处理的方法。这项工作将提供对原子和纳米级界面属性的基本了解，并将这些研究与全面积最先进的CSPC器件的光学和电学属性以及器件性能联系起来。这个项目将产生广泛的影响，通过培养一支跨学科、跨大学和多样化的研究生和本科生团队跨越两所大学。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical:Solar cells convert sunlight to electricity and have several unique advantages. They operate without monitoring, do not emit pollution, and can be made from earth-abundant and non-toxic materials. The use of solar energy is rapidly growing, but it still accounts for only a small fraction of electricity production. To increase their share of the energy market, the cost of making and operating solar cells must be decreased and their efficiency must increase. Carrier-selective passivating contacts hold the promise of doing just that. Such contacts increase cell efficiency by reducing electrical losses at the interface between the layer of a solar cell that absorbs light and the metal contacts that extract electrical current. This project will use a unique way to improve the fundamental understanding and control of loss mechanisms in solar cells with such contacts. Laser processing provides a way to electrically activate carrier-selective passivating contacts by selectively depositing laser energy into a selected layer with fine control at high speed. This process has the potential to increase the power conversion efficiency of solar cells while maintaining low temperature and high throughput, thereby decreasing the cost per kilowatt-hour of energy produced. The generated knowledge will improve various types of solar power generating as well as other electronic and photonic devices. The proposal brings together an experienced multidisciplinary team with expertise in solar cell fabrication, laser processing, and atomic-scale characterization. The PIs will engage in extensive outreach to local high schools, museums, and libraries. The economic impact will be amplified through work with solar cell manufacturing companies. This project will help society meet its future energy needs using fewer resources at a reduced cost while preventing pollution and climate change.Technical:This project encompasses carrier-selective passivating contact development, photovoltaic device fabrication, laser processing, and imaging at the atomic level using transmission electron microscopy. Carrier-selective passivating contacted (CSPC) devices are a promising next generation technology for photovoltaic devices because they eliminate the two primary loss mechanisms: the direct metal contact to silicon and dopant diffusion into the bulk. A fundamental understanding of the interface quality, dopant type, dopant activation (and potential diffusion), tunneling mechanism, and the effect of the passivation layer is still lacking. Through a combination of device modeling, fabrication and laser processing experiments, and transmission electron microscopy studies, the quantitative degree of CSPC band bending and band gaps; effect of thermal crystallization on optical absorption, implied open-circuit voltage and defect content; and independent control of dopant activation, crystallization, grain growth, and dopant diffusion will be investigated to provide the photovoltaic industry a better understanding of CSPC for is manufacturing adoption. The novelty of the aim of this study lies in the use of pulsed laser processing of CSPC to provide a non-contact way of annealing the device with surface heating only. This work will provide a fundamental understanding of the interface properties at the atomic and nanoscale level and relate these studies to the optical and electronic properties as well as to device performance of a full-area state-of-the-art CSPC device. This project will have a broad impact by training an interdisciplinary, interuniversity, and diverse team of graduate and undergraduate students across two universities.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.