Structure and morphology of stability-enhanced halide perovskite nanocrystals for efficient visible light emission

• Applicants: Professor Dr. Knut Müller-Caspary; Professor Dr. Alexander Urban
• Subject Area: Experimental Condensed Matter Physics ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564332417

Renewable energy and improved energy efficiency are crucial to address the growing concerns of climate change, energy security, and sustainable development. Nanomaterials, characterized by their unique properties, can improve the performance and cost-effectiveness of solar cells, batteries, and supercapacitors, offering groundbreaking solutions to enhance renewable energy technologies and efficiency measures. Halide perovskites are fascinating due to their exceptional properties, including high light absorption, tunable bandgap, and excellent charge-carrier mobility. Additionally, their low-cost production and ease of fabrication make them attractive for scalable manufacturing. Despite these positive attributes, several aspects of halide perovskites, including stability and full-spectral efficiency, are still impeding widespread application. Here, we investigate two halide perovskite systems: i) highly-confined anisotropic CsPbBr3 NCs for efficient light emission in the blue spectral range and ii) block copolymer-encapsulated MAPbX3 NCs with enhanced stability to environmentally-induced degradation and ion diffusion. Optimization of these nanosystems requires an in-depth understanding of their morphology and composition, how these are affected by synthesis and post-processing steps, and how they can be specifically modified. We closely interlink synthesis, optical, and electron microscopic characterization with efficient feedback loops to understand the interplay between these intriguing nanomaterials' composition, morphology, and optoelectronic properties. The research is structured into two Research Lines (RL), each focusing on one of the halide perovskite nanosystems. In RL I, we concentrate on synthesizing the highly-confined NCs and how dimensionality and thickness can be controlled. In RL II, we strive to discover and enhance the inner structure of the hybrid NCs, which has proven elusive due to the significant organic shielding. Through the close cooperative interaction, we plan to achieve the following: 1) In the complex parameter space of synthesis procedures, optical properties, and structure, a phase diagram is developed to serve as a basis for further halide perovskite research. 2) Post-synthetic stabilization strategies, such as chemical and thermal processing, are systematically developed to realize spectrally and structurally stable nanoemitters at the laboratory level. 3) Specifically tailored, iterative, low-dose TEM measurements will help to systematically connect the properties of this promising material system with the structure (e.g., halide perovskite/lipid layer interfaces) with up to atomic resolution.

• DFG Programme: Research Grants