CAREER: Printing and Interface Engineering of Colloidal Nanocrystals for Flexible Thermoelectrics and Electronics

该学院早期职业发展奖旨在开发在热电材料和器件的形成中使用纳米晶体的新方法。柔性热电薄膜和电子薄膜有可能对能量收集、冷却和柔性电子产品的广泛应用产生影响。传统的热电和电子设备是刚性的，使用复杂和相对昂贵的工艺制造。添加剂制造或基于印刷的方法提供了低成本和高度可扩展的手段，将具有独特性质的胶体纳米晶组装成柔性热电和电子设备。热电材料的纳米晶由于其尺寸小，可以形成油墨，可以打印到柔性基板上，并形成有用的近最终形状结构。在工作装置中需要了解和控制纳米晶体及其相互界面的热学和电学性质。纳米晶薄膜的界面化学和热电行为在工艺条件下的响应是获得最高性能热电材料的关键。这些基于纳米晶体的工艺和材料可能会打开影响美国制造业的新应用领域，并打开热电以外的新应用领域。综合研究和教育计划为广泛的受众提供教育机会，包括开发热电开发教育工具包，以及机构和外展计划，通过参与NSF REU/RET、LSAMP、e-Girls和e-Camp，提高K-12学生、教师和未被充分代表的群体成员对STEM职业的兴趣，支持制造业和先进材料领域的劳动力发展，以满足对可持续能源和电子技术日益增长的需求。这项研究旨在实现类似于大宗载流子的移动性，并使热电优值系数ZT与当前最先进的柔性薄膜相比增加两倍以上。这项研究将解决在可扩展和低成本的制造过程中将纳米晶体转化为有用形式的迫切需求。该项目将完成四个目标，以建立从纳米尺度到宏观尺度的胶体纳米晶加工新范式：(1)纳米晶的合成，并控制其尺寸、表面化学和掺杂，(2)印刷和烧结柔性薄膜，具有受控的界面化学，(3)建立加工-结构-性能关系，以及(4)设计和印刷概念验证装置。研究成果不仅将显著推进柔性热电和电子材料的制造工艺，还将在添加剂打印平台内形成和使用功能纳米晶材料方面产生新的知识。

This Faculty Early Career Development (CAREER) award looks to develop new approaches to the use of nanocrystals in the formation of thermoelectric materials and devices. Flexible thermoelectric and electronic films have the potential to impact a broad range of applications in energy harvesting, cooling and flexible electronics. The conventional thermoelectric and electronic devices are rigid, and fabricated using complex and relative costly processes. Additive manufacturing or printing-based approaches offer low-cost and highly scalable means to assemble colloidal nanocrystals of unique properties into flexible thermoelectric and electronic devices. Nanocrystals of thermoelectric materials, because of their small size, can be formed into inks which can be printed onto flexible substrates and in useful near-final-form structures. The thermal and electrical properties of the nanocrystals and their mutual interfaces need to be understood and controlled in working devices. The interfacial chemistry and the response of the nanocrystal-based film's thermoelectric behavior under processing conditions is critical to achieving the highest performance thermoelectric materials. These nanocrystal-based processes and materials could open new application areas impacting US manufacturing and opening new application area beyond thermoelectrics. The integrated research and education program provides educational opportunities to broad range of audiences, including the development of educational kits in thermoelectrics development and institutional and outreach programs to enhance interest from K-12 students, teachers and members of underrepresented groups in STEM careers through participation in NSF REU/RET, LSAMP, e-Girls, and e-Camp, to support workforce development in the manufacturing and advanced materials areas to address increasing needs in the sustainable energy and electronic technologies.This research aims to achieve bulk-like charge carrier mobility and an over two-fold increase in thermoelectric figure of merit ZT compared with current state-of-the-art flexible films. The research will address a pressing need to convert the nanocrystals into a useful form within a scalable and low-cost manufacturing process. The project will complete four objectives to establish a new paradigm for processing colloidal nanocrystals from nanoscale-to-macroscale: (1) synthesis of nanocrystals, and control their size, surface chemistry and doping, (2) print and sinter flexible films, with controlled interfacial chemistry, (3) establish the processing-structure-property relationship, and (4) design and print proof-of-concept devices. The research outcomes will not only significantly advance the manufacturing processes for flexible thermoelectric and electronic materials, but also generate new knowledge in the formation and use of functional nanocrystalline materials within an additive printing platform.