Synthesis of New Chalcogenide-Containing Perovskite Semiconductor Nanomaterials: Towards Earth-Abundant and Non-Toxic Solar Absorbers

第一部分：非技术总结用于可再生能源生产和储存的新材料的发现和提炼是21世纪材料化学最具影响力的挑战之一。最近，用于太阳能电池的一类被称为卤化铅钙钛矿的材料受到了相当大的关注，但由于担心铅的毒性，这些材料可能会受到限制。因此，需要不断地开发新型半导体材料，这种材料可以显示出同样有希望的特性，但没有相应的缺点；它们应该是无毒的、高度稳定的、可溶液处理的，并且理想地由富含地球的元素组成。许多具有潜在潜在性能的材料已经在计算上被提出，但在实验上只实现了一小部分。这项研究项目得到材料研究部固态和材料化学方案的支持，涉及开发新的合成方法，以使用溶液合成来获得新兴和拟议的无机半导体。该项目专注于两类含硫或硒的无铅钙钛矿材料，它们的合成目前要么未知，要么非常有限。这些材料在溶液中的简便合成路线的开发允许对它们的性能进行实验验证，并为它们在太阳能电池或其他设备中的潜在应用奠定了基础。通过参与该项目，研究生和本科生将接受材料化学和可再生能源科学方面的培训，为他们未来在能源研究和绿色技术领域的职业生涯做好准备。与这项工作有关的概念，以及一般的材料化学，也正在被开发成课程作业，以接触到密西西比州立大学更广泛的学生。第二部分：技术总结本研究项目致力于开发两类基于钙钛矿晶格的硫系无机材料，这两类材料被认为是杂化卤化铅钙钛矿的无毒和富含稀土的替代品，但其合成方法尚不清楚或不发达。首先，该研究小组的目标是使用溶液合成方法合成硫系钙钛矿，包括BaZrS3和SrHfS3作为胶体纳米晶。合成方法包括使用活性硫化物和金属前体(例如三甲基硅基硫化物和金属醇盐和酰胺)，使用单一来源的前体，如金属二硫代氨基甲酸盐和异双金属硫酸盐簇合物，以及氧化物纳米晶体的硫化。作为纳米晶体的合成允许这些材料潜在地用作溶液处理的胶体油墨。此外，研究小组正在研究通过对硫化物或卤化物前体的胶体纳米晶进行阴离子交换等方法来制备混合阴离子卤化物-硫系钙钛矿，如CsBiSi2、CsSbSi2和CsSnS2Cl.通过这种方法，可以获得在热平衡条件下通过直接合成难以或不可能获得的亚稳定的成分、结构和形貌。对所制备的材料的组成、结构和光学性质进行了表征，并与计算预测进行了比较。该项目由材料研究部内的固态和材料化学项目支持。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。

PART 1: NON-TECHNICAL SUMMARYThe discovery and refinement of new materials for renewable energy production and storage is one of the most impactful challenges for materials chemistry in the 21st century. Recently, there has been considerable focus on a class of materials known as lead halide perovskites for applications in solar cells, but they may be limited by concerns about the toxicity of lead. Therefore, there is an ongoing need for the development of emerging classes of semiconductor materials which could show similarly promising properties, but without the corresponding drawbacks; they should be non-toxic, highly stable, solution-processible, and ideally composed of earth-abundant elements. Many materials with potentially promising properties have been proposed computationally, but only a small subset have been realized experimentally. This research project, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, involves the development of new synthetic methods to access emerging and proposed inorganic semiconductors using solution synthesis. The project focuses on two classes of lead-free perovskite materials containing sulfur or selenium whose synthesis is currently either unknown or very limited. The development of facile synthetic routes to these materials in solution allows for experimental validation of their properties and lays the groundwork for their potential application in solar cells or other devices. Through their involvement in this project, graduate and undergraduate students are trained in materials chemistry and in renewable energy science, preparing them for future careers in energy research and green technology. Concepts related to this work, and materials chemistry in general, are also being developed into coursework to reach a broader audience of students at Mississippi State University. PART 2: TECHNICAL SUMMARYThis research project focuses on the development of two classes of chalcogenide-containing inorganic materials based on a perovskite lattice, which have been proposed as promising non-toxic and earth-abundant replacements for the hybrid lead halide perovskites, but whose synthesis is either unknown or underdeveloped. First, the research team is targeting the synthesis of chalcogenide perovskites including BaZrS3 and SrHfS3 as colloidal nanocrystals using solution synthesis approaches. Synthetic methods include the use of reactive sulfide and metal precursors (e.g., trimethysilyl sulfide and metal alkoxides and amides), the use of single-source precursors such as metal dithiocarbamates and heterobimetallic metal thiolate clusters, and the sulfurization of oxide nanocrystals. Synthesis as nanocrystals allows for the potential use of these materials as colloidal inks for solution-processing. Additionally, the research team is investigating the preparation of mixed-anion halide-chalcogenide perovskites such as CsBiSI2, CsSbSI2, and CsSnS2Cl, through approaches such as anion exchange on colloidal nanocrystals of chalcogenide or halide precursors. Through this approach, it is possible to access compositions, structures, and morphologies that may be metastable and difficult or impossible to access through direct synthesis under thermal equilibrium conditions. The materials prepared are characterized in terms of their compositional, structural, and optical properties and compared to computational predictions. This project is supported by the Solid State and Materials Chemistry program within the Division of Materials Research.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.