Collaborative Research: Chemical Control of Polymer/PbS Blends for PV Applications

合作PI名称：Moule (Lead), Ganapathysubramanian， Ginger提案编号：1436273 - 1437636 - 1437016太阳代表了地球上最丰富的潜在无污染能源。将光能转化为电能的太阳能电池基于集成在光伏（PV）装置中的有机聚合物，如果太阳能转换效率可以提高，则为可再生电力生产提供了一条潜在的低成本途径。提高有机聚合物太阳能电池效率的关键是更好地了解聚合物薄膜内材料的分子排列。该项目将应用新型电子显微镜工具来了解材料加工如何影响用于光伏（PV）应用的聚合物/纳米颗粒薄膜中材料的三维排列。低成本的硫化铅纳米颗粒（PbS）与导电聚合物的混合物将被研究，因为这些混合物最近显示出很高的光伏效率，并且因为这些材料在电子显微镜下具有很高的成像对比度。电子断层扫描将生成混合物中物质的三维浓度图。这些图将用于将加工条件与聚合物/纳米颗粒薄膜内的材料排列相关联。然后，这些信息将与设备性能相关联，以便确定基于有机聚合物制造更好的太阳能电池的策略。这项工作将由一个合作团队进行，该团队将同时推进聚合物/纳米颗粒薄膜制造、三维电子显微镜成像和图像计算分析的科学，以揭示纳米级结构。这种合作方法有可能揭示任何其他技术无法测量的光学和电子特性的结构起源。在扩大参与的教育和活动方面，该项目将提供多样化的外展和教育机会，包括通过男女童子军和4H与儿童互动，在参加人数众多的当地节日中进行公共教育，在课堂上纳入研究材料，以及保留女工程专业学生。该项目将开发和使用新的电子断层扫描工具，以了解材料加工如何影响用于光伏（PV）应用的混合聚合物/纳米颗粒薄膜中材料的三维排列。低成本的硫化铅纳米颗粒（PbS）与导电聚合物的混合物将被研究，因为这些混合物最近显示出很高的光伏效率，并且因为这些材料在电子显微镜下具有很高的成像对比度。该电子显微镜工具基于高角度环形暗场扫描电子断层扫描（HAADF-ET）结合离散代数重建技术（DART），生成分辨率小于3立方纳米的有机/无机混合光伏材料三维（3D）材料浓度图。三维数据的形态描述符的开发，包括相的数量、每相的浓度比、域的大小、域的连通性、路径的弯曲度、各向异性和域的表面积等特征，将使用基于图的分析来测量。这些信息将用于将混合有机/无机电子薄膜中重组位点的形态、结构非均质性和物理分布与光电性能和光伏性能联系起来。在扩大参与的教育和活动方面，该项目将提供多样化的外展和教育机会，包括通过男女童子军和4H与儿童互动，在参加人数众多的当地节日中进行公共教育，在课堂上纳入研究材料，以及保留女工程专业学生。

Collaborative PI Names: Moule (Lead), Ganapathysubramanian, Ginger Proposal Numbers: 1436273 - 1437636 - 1437016 The sun represents the most abundant potential source of pollution-free energy on earth. Solar cells for conversion of light to electricity based on organic polymers integrated into a photovoltaic (PV) device offer a potentially low-cost route for renewable electricity production if the solar energy conversion efficiency can be improved. The key to improving the efficiency of organic polymer based solar cells is to better understand the molecular arrangement of the materials within the polymer film. This project will apply novel electron microscopy tools to understand how materials processing affects the three-dimensional arrangement of materials in polymer/nanoparticle films designed for photovoltaic (PV) applications. Mixtures of low-cost lead sulfide (PbS) nanoparticles with electrically conducting polymers will be studied because these mixtures have shown recent high photovoltaic efficiency, and because these materials have high imaging contrast by electron microscopy. The electron tomography will generate three dimensional concentration maps of materials within the mixture. These maps will be used to correlate processing conditions to material arrangement within the polymer/nanoparticle film. This information will then be correlated to device performance in order to identify strategies for making better solar cells based on organic polymers. The work will be carried out by a collaborative team that will simultaneously advance the science of polymer/nanoparticle film fabrication, three dimensional electron microscope imaging, and computational analysis of the images to reveal nanoscale structure. This collaborative approach has the potential uncover the structural origin of optical and electronic properties that cannot be measured by any other technique. With respect to education and activities for broadening participation, the project will provide a diverse set of outreach and educational opportunities that include interaction with children through the Boys and Girls Scouts and 4H, public education at well attended local festivals, inclusion of research material in classes, and retention of female engineering students. Technical Description This project will develop and use new electron tomography tools to understand how materials processing affects the three-dimensional arrangement of materials in hybrid polymer/nanoparticle films designed for photovoltaic (PV) applications. Mixtures of low-cost lead sulfide (PbS) nanoparticles with electrically conducting polymers will be studied because these mixtures have shown recent high photovoltaic efficiency, and because these materials have high imaging contrast by electron microscopy. The electron microscopy tool is based on high-angle annular dark-field scanning electron tomography (HAADF-ET) combined with the discrete algebraic reconstruction technique (DART) to generate three-dimensional (3D) material concentration maps with resolution of less than three cubic nanometers for the hybrid organic/inorganic photovoltaic materials. Development of morphology descriptors of the 3D data, including features like the number of phases, concentration ratio in each phase, domain size, domain connectivity, tortuosity of pathways, anisotropy and domain surface area will be measured using graph-based analysis. This information will be used to correlate morphology, structural heterogeneity, and physical distribution of recombination sites in mixed organic/inorganic electronic films to optoelectronic properties and photovoltaic performance. With respect to education and activities for broadening participation, the project will provide a diverse set of outreach and educational opportunities that include interaction with children through the Boys and Girls Scouts and 4H, public education at well attended local festivals, inclusion of research material in classes, and retention of female engineering students.