Solar Cells From Earth-Abundant Materials

[32955]太阳能光伏电池（PV）可以提供丰富和可持续的电力供应，对环境的影响相对较小。然而，它们目前的高成本和稀有元素的使用阻碍了太阳能光伏发电提供大量的能量。这项拟议的研究旨在为廉价的太阳能光伏制造过程提供科学基础，该过程使用地球上丰富的材料，即足够数量的元素来生产太阳能光伏当前所需的所有能源。这些常见元素包括锡、锌、铜、铝、氧和硫，以及数量少得多的不常见元素，如锗和锑。这些材料将用于非常薄的层，因此与晶体硅太阳能电池相比，所需的材料要少得多。最初的研究方法将使用原子层沉积（ALD），由足够丰富的元素制成太阳能电池所需的所有层。ALD提供精确的成分控制，纯度和厚度，因此可以确定这些细胞的潜在性能。然而，ALD速度慢且使用昂贵的真空设备，因此不适合作为大规模生产的廉价方法。降低制造成本的关键是使用廉价的非真空设备快速连续生产具有集成互连的薄膜太阳能电池。因此，在研究的后期阶段，化学气相沉积（CVD）将用于制造太阳能电池的层。CVD可以比ALD更快地制作所需的层，并且可以在大气压下操作，而不需要真空设备。提出的研究计划旨在促进对地球丰富的半导体材料集成到太阳能光伏器件的结构和特性的理解。所提出的吸收材料（如硫化锡）的结构与传统半导体的结构不同。电子结构，能带，光学性质和缺陷的结构将表征这些知之甚少的材料。将特别注意吸收材料的晶界和表面的结构和电学性质。化学钝化将试图使通常位于晶界和表面的重组中心失活，纳米级分析将用于定位位于晶界的单个原子。薄膜的高速生长是高效制造光伏薄膜的关键步骤。为了了解生长过程，将识别生长过程中在表面产生的化学物质，以及离开表面的副产品。将汽源转化为薄膜的表面反应动力学也将被测量。更广泛的影响基于地球资源丰富，环保材料的光伏设备的制造是实现太阳能发电可持续性的首要任务。这项拟议研究的更广泛影响强调了研究生培训背景下的技术转让。具体而言，将努力将研究转化为制造导电玻璃基板的工业使用的制造平台。

1032955GordonIntellectual MeritSolar photovoltaic cells (PV) can provide an abundant and sustainable supply of electricity with relatively low environmental impact. However, their present high cost and use of scarce elements prevent solar PV from delivering a significant amount of energy. This proposed research seeks to provide a scientific foundation for an inexpensive solar PV manufacturing process using earth-abundant materials, i.e. elements that are available in sufficient amounts to produce all current energy needs by solar PV. These common elements include tin, zinc, copper, aluminum, oxygen and sulfur, along with much smaller amounts of less common elements, such as germanium and antimony. These materials will be used in very thin layers, so that much less material is needed compared to crystalline silicon solar cells. The initial research approach will use atomic layer deposition (ALD) of all the layers required in a solar cell made from sufficiently abundant elements. ALD offers precise control of composition, purity and thickness, so that the potential performance of these cells can be determined. However, ALD is slow and uses expensive vacuum equipment, so it is not suitable as an inexpensive method for mass production. The key to lowering manufacturing cost are rapid and continuous production using inexpensive, non-vacuum equipment to make thin-film solar cells with integrated interconnections. Thus, in later stages of the research, chemical vapor deposition (CVD) will be used to make the layers of the solar cell. CVD can make the required layers much more quickly than ALD, and can also be operated at atmospheric pressure without the need for vacuum equipment. The proposed research plan is designed to advance the understanding of structure and properties underlying the integration of earth-abundant semiconductor materials into solar PV devices. The structures of the proposed absorber materials, such as tin sulfide, are different from those of conventional semiconductors. Electronic structures, band energies, optical properties and structures of defects will be characterized for these poorly understood materials. Particular attention will be paid to the structure and electrical properties of grain boundaries and surfaces of the absorber material. Chemical passivation will be attempted to deactivate the recombination centers that typically reside at grain boundaries and surfaces, and nano-scale analyses will be used to locate individual atoms located at the grain boundaries. High-speed growth of the thin films is a critical step in the efficient manufacture of thin-film PV. To understand the growth process, chemicals created on the surface during growth will be identified, along with the byproducts that leave the surface. The kinetics of the surface reactions that convert the vapor sources into the thin films will also be measured. Broader ImpactsThe fabrication of PV devices based on earth-abundant, environmentally benign materials is a top priority for achieving sustainability of electricity production from solar energy. The broader impacts for this proposed research emphasize technology transfer in the context of graduate student training. Specifically, efforts will be made to translate the research to manufacturing platforms used by industry that make conductive glass substrates.