CAS: Multinary Semiconductor Nanocrystals: Increasing Complexity through Solution-Phase Chemistry

在化学系大分子、超分子和纳米化学项目的支持下，爱荷华州立大学的Javier Vela教授将研究由多种元素组成的新兴和技术相关的半导体，这种化学类型仍然不发达。由于这些半导体将由无毒且富含地球元素制成，因此这项研究可能会为清洁和可再生能源的巨大潜力开辟新的环保和低成本半导体类别。为了扩大参与并帮助培养下一代高素质和多样化的纳米化学科学家，Vela小组将为第一代或代表性不足的本科生提供实习机会，为博士后的职业发展做出贡献，并为一年级研究生申请研究奖学金做准备。根据该奖项，Javier Vela教授和他的团队将利用他们在光学活性纳米材料的合成和光谱研究方面的专业知识：(1)研究用于光伏发电的钙钛矿硫系纳米晶体的演变，(2)开发用于光电子学的锡基四元硫系纳米晶体，以及(3)测试用于二氧化碳还原的三元四面体纳米晶体。与单晶或块状半导体的高温合成相比，从溶液中合成纳米级多半导体尤其具有挑战性。与一元或二元纳米晶体不同，由多个前驱体在一个单一的，同时的步骤中形成的多纳米晶体的成核和生长可能是熵要求很高的。事实上，通过界面化学作用，金属或二元种子往往先于最终的纳米多相形成。此外，多晶半导体通常采用一种以上的多晶型，每一种多晶型可以包含混合占用位点或“着色”模式。该项目将专注于多半导体，除了具有耐缺陷性外，还能在高温、高湿或连续照明条件下表现出更高的稳定性。从现成的前体合成胶体有望作为一个可持续的途径，进入广泛的功能多纳米晶体。结构表征、光谱研究和计算之间的协同作用有望为更好地理解多纳米晶的多态性和结构提供帮助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Javier Vela of Iowa State University will study emerging and technologically relevant semiconductors comprised of multiple elements for which this type of chemistry remains underdeveloped. Because these semiconductors will be made from non-toxic and earth abundant elements, this research may open new classes of environmentally friendly and low-cost semiconductors of great potential for clean and renewable energy. To broaden participation and help build the next generation of highly qualified and diverse nanochemistry scientists, the Vela group will offer internships to first generation or under-represented undergraduates, contribute to the career development of postdoctoral fellows, and prepare first year graduate students to apply for research fellowships.Under this award, Professor Javier Vela and his team will utilize their expertise in the synthesis and spectroscopic study of optically active nanomaterials to: (1) study the evolution of perovskite chalcogenide nanocrystals for photovoltaics, (2) develop tin-based quaternary chalcohalide nanocrystals for optoelectronics, and (3) test ternary tetrahedral nanocrystals for carbon dioxide reduction. Compared to the high temperature synthesis of single crystal or bulk semiconductors, the synthesis of nanoscale multinary semiconductors from solution can be particularly challenging. Unlike unary or binary nanocrystals, the nucleation and growth of multinary nanocrystals from multiple precursors in a single, simultaneous step can be entropically demanding. In fact, metallic or binary seeds often precede the formation, through interfacial chemistry, of the final multinary nanophase. Further, multinary semiconductors often adopt more than one polymorph, each of which may contain mixed-occupancy sites or “coloring” patterns. This project will focus on multinary semiconductors that, in addition to being defect-tolerant, show increased stability to conditions of heat and high humidity or under continuous illumination. Colloidal synthesis from readily available precursors is expected to serve as a sustainable route into a wide range of functional multinary nanocrystals. Synergy among structural characterization, spectroscopic studies, and computation is expected to provide for a better understanding of multinary nanocrystal polymorphism and structure.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.