PART 1: NON-TECHNICAL SUMMARY The 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 SUMMARY This 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.