Synthesis of Stoichiometric Pyrite Photovoltaic Absorbers

技术综述：将采用两种策略来制备薄膜形式的相纯黄铁矿(β-FeS2)。首先，我们将利用我们的经验激活纳米结构赤铁矿(α-Fe2O)光阳极来分解水。热力学表明，赤铁矿可以直接转化为黄铁矿，绕过了使用铁作为前驱体时遇到的不希望看到的相。第二种方法将使用脉冲等离子体增强化学气相沉积(PECVD)，这是一种循环技术，提供阿斯特罗姆水平的薄膜厚度控制。一个关键因素是使用等离子体辅助制造工艺来提供增强的S活性和对曝光的精确控制。调查将通过独特的现场诊断能力和对材料特性和设备性能的综合评估来实现。在这两种情况下，黄铁矿都将与导电的氧化锡/赤铁矿结构紧密接触形成，除了提供便于器件制造的先进正面接触外，还将允许询问光电性能。非技术摘要：新的低成本、富含地球的太阳能电池技术需要产生可持续发展所需的太瓦级功率。从潜在容量和成本来看，黄铁矿是最有前景的太阳能转换半导体。它是一种无毒、富含稀土的化合物，可以非常有效地吸收光伏应用中的光。由这种材料制成的单结太阳能电池理论上可以达到25%的效率，但到目前为止，在有限的研究中获得的最好结果是3%。该提案中描述的工作将建立成功生产光伏所需的薄膜形式的相纯黄铁矿所需的科学知识基础。该项目的主要贡献将是对研究生和本科生进行材料科学和无机薄膜光伏先进加工方面的教育和高级培训。PI的小组将继续他们的K-12外展工作，为学生人数较少的学区的教师开发与可再生能源有关的研讨会材料。该项目得到了固态和材料化学计划的支持。

TECHNICAL SUMMARY:Two strategies will be pursued to produce phase-pure pyrite (beta-FeS2) in a thin film form. First, we will leverage our experience activating nanostructured hematite (alpha-Fe2O3) photoanodes for water splitting. Thermodynamics suggest that hematite can be directly transformed to pyrite, bypassing undesired phases that are encountered when using iron as a precursor. The second approach will employ pulsed plasma-enhanced chemical vapor deposition (PECVD), a cyclic technique that provides Angstrom-level control over film thickness. A key element is the use of plasma-assisted fabrication processes to provide enhanced S activity and precise control over exposure. The investigations will be informed by unique in situ diagnostic capabilities and comprehensive evaluation of material properties and device performance. In both cases pyrite will be formed in intimate contact with a conducting tin oxide/hematite structure that will allow interrogation of the opto-electronic performance, in addition to providing an advanced front contact that facilitates device fabrication. NON-TECHNICAL SUMMARY:New low cost, earth abundant solar cell technologies are required to generate the TW levels of power required for sustainability. Pyrite is the most promising semiconductor for solar energy conversion in terms of potential capacity and cost. It is a non-toxic, earth abundant compound that can very efficiently absorb light for photovoltaic applications. Single junction solar cells derived from this material are theoretically capable of 25% efficiency, but the best results obtained in the limited studies to date are 3%. The work described in this proposal will establish the scientific knowledge base required to successfully produce phase-pure pyrite in a thin film form required for photovoltaics. A major contribution of this project will be the education and advanced training of both graduate and undergraduate students in the materials science and advanced processing of inorganic thin film PV. The PI's group will continue their K-12 outreach work, developing workshop materials related to renewable energy for teachers in school districts with large populations of underrepresented students.This project is supported by the Solid State and Materials Chemistry program.