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，爱荷华州立大学的哈维尔·贝拉教授将研究由多种元素组成的新兴和技术相关的半导体，这种类型的化学仍然不发达。由于这些半导体将由无毒和富含稀土的元素制成，这项研究可能会开辟新的环保和低成本半导体类别，具有巨大的清洁和可再生能源潜力。为了扩大参与，帮助培养高素质和多样化的下一代纳米化学科学家，VELA团队将为第一代或未被充分代表的本科生提供实习机会，为博士后研究员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。在这一奖项下，哈维尔·贝拉教授和他的团队将利用他们在光学活性纳米材料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型硫化物纳米晶体的演变；(2)用于光电子学的锡基四元卤化物纳米晶体；以及(3)测试用于二氧化碳减排的三元四面体纳米晶体。与单晶或块体半导体的高温合成相比，从溶液中合成纳米级多元半导体可能特别具有挑战性。与一元或二元纳米晶体不同，多元纳米晶体的成核和生长在一个单一的、同时的步骤中可能是非常苛刻的。事实上，通过界面化学，金属或二元晶种往往先于最终的多元纳米相的形成。此外，多元半导体通常采用不止一种多晶型，每一种多晶型都可能包含混合占位或“着色”图案。该项目将专注于多元半导体，这些半导体除了具有缺陷容忍性外，还可以在高温和高湿度条件下或在连续照明下表现出更高的稳定性。从容易获得的前体进行胶体合成有望成为一条可持续发展的途径，成为一种广泛的功能多元纳米晶体。结构表征、光谱研究和计算之间的协同作用有望提供对多进制纳米晶体多态和结构的更好理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.