SusChEM - Collaborative Research: Universal Understanding of Push-Pull D-A compounds and Prescriptive Materials Design for Optimized Bulk-Heterojunction Photovoltaics

太阳代表着地球上最丰富的潜在可持续能源。利用有机导电聚合物将光能转化为电能的太阳能电池——有机光伏装置——为可再生能源发电提供了一条潜在的低成本途径。一般来说，低成本是通过使用潜在廉价的聚合物材料和可扩展的聚合物薄膜加工来提供的。然而，目前的有机聚合物太阳能电池目前受到低效率和高材料成本的困扰。由于改进的材料对商业可行性至关重要，本项目的目标是开发和表征更有效、低成本、可持续的有机光伏设备材料。这些新材料将以方英烷（一类有机染料材料）为基础。这项工作的关键创新是开发和使用理论建模工具来筛选优化器件性能特征的最佳候选分子。然后，候选材料将使用绿色化学方法合成，以实现低成本、可持续的材料，并保持所需的性能。与此项目相关的教育活动将通过罗切斯特理工学院的国家聋人研究所为听障学生提供参与研究的机会。基于有机聚合物的光伏（OPV）太阳能电池目前存在效率低、制造成本高的问题，部分原因是难以获得严格的聚合物形态控制。如果分子设计规则可以从第一性原理的角度实现，以优化材料性能以获得最佳器件性能，那么设计用于满足带隙和能级要求的供体-受体类型化合物可以获得更高的效率。Squaraines是一类有机光导体，作为OPV器件的小带隙有机分子，具有多种潜在优势，包括易于纯化，可扩展和一致的合成，以及可调节的功能，用于规定的分子设计。本研究将结合理论、材料合成和关键特性表征研究，为基于方碱化合物的OPV器件中供体-受体分子的分子设计开发一个基本框架。第一个目标是开发和使用理论模型来模拟一系列方嘌呤的基于形态学的光谱学，这些化合物代表了完成受体型OPV靶标的总集合。该理论将描述形态和分子结构如何影响关键过程，包括吸收光谱、激发态和分子间电荷转移积分。因此，当模型通过光谱学进行实验验证时，对这些过程的更全面理解将导致对理想材料的规范设计，优化OPV所需的所有关键特性，包括太阳光谱吸收重叠、激子扩散、激子解离和电荷输运。基于第一个目标的发现，在第二个目标下，方英酮将被修改，以便在无毒溶剂中加工，以实现低成本，可持续和可扩展的材料合成。器件制造和测试将确认这些材料中哪些关键的OPV性能得到了改善。总体而言，本研究有望使人们更全面地了解平方分子的激发态特性，基于合理的分子设计优化其关键特性以获得最佳的OPV器件性能，以及可扩展和可持续的方法来合成这些材料并将其集成到体异质结OPV器件中。

The sun represents the most abundant potential source of sustainable energy on earth. Solar cells that use organic conducting polymers to convert light to electricity - organic photovoltaic devices - offer a potentially low-cost route for renewable electricity production. In general, the low cost is offered through use of potentially inexpensive polymer materials and scalable polymer film based processing. However, current organic polymer solar cells currently suffer from low efficiencies combined with high material costs. Since improved materials are critical to commercial viability, the goal of this project is to develop and characterize more effective, low cost, sustainable, materials for organic photovoltaic devices. These new materials will be based on the squaraines, a class of organic dye materials. The key innovation of this effort is the development and use of theoretical modeling tools to screen for the best candidate molecules that optimize device performance characteristics. The candidate materials will then be synthesized using methods of green chemistry to enable low cost, sustainable materials that preserve the desired properties. The educational activities associated with this project will provide research participation opportunities for hearing-impaired students through the National Institute for the Deaf at the Rochester Institute of Technology.Organic polymer-based photovoltaic (OPV) solar cells currently suffer from low efficiencies and high manufacturing costs, due in part to difficulties associated with attaining tight polymer morphology control. Higher efficiencies can be obtained with donor-acceptor type compounds designed to address bandgap and energy level requirements, if the molecular design rules can be realized from a first-principles perspective to optimize material properties for best device performance. Squaraines are class of organic photoconductors that offer several potential advantages as small band gap organic molecules for OPV devices, including ease of purification, scalable and consistent synthesis, and tunable functionality for prescriptive molecular design. This research will combine theory, materials synthesis, and critical property characterization studies to develop a fundamental framework for molecular design of donor-acceptor molecules in OPV devices based on squaraine compounds. The first objective is to develop and use theoretical models to simulate the morphology-based spectroscopy for a series of squaraines, compounds representative of the total set of done-acceptor type OPV targets. The theory will describe how morphological and molecular structure influences critical processes, including absorption spectrum, the excited states, and the intermolecular charge transfer integral. Thus, when the models are experimentally validated through spectroscopy, a more complete understanding of these processes will lead to a prescriptive design for idealized materials optimized at all critical properties needed for OPV, including solar spectrum absorption overlap, exciton diffusion, exciton dissociation, and charge transport. Based on the findings from the first objective, under the second objective, squaraines will be modified for processing in non-toxic solvents to enable low cost, sustainable, and scalable materials synthesis. Device fabrication and testing will confirm which critical OPV properties have been improved in these materials. Overall, this research is expected to lead to a more a comprehensive understanding of the excited state properties of squaraines, optimization of their critical properties for best OPV device performance based on rational molecular design, and scalable and sustainable methods for the synthesis of these materials and their integration into bulk heterojunction OPV devices.