Development of Fully-Printed and Eco-Friendly Light-Emitting Diodes Using Organometal Hybrid Perovskite Emitters

Florida State University, Tallahassee FL

Investigators

Abstract

Abstract: Non-Technical: Light-emitting diodes have evolved as important commercial products. They are believed to replace traditional incandescent and fluorescent light bulbs for displays and lighting luminaires. While the brightness and stability of light-emitting diodes have greatly improved over the past decade, cost per diode still remains relatively high. This has become a bottleneck limiting their wide market penetration. This project aims to develop a revolutionary technology that can employ scalable printing processes to fabricate large area light-emitting diodes with high throughput. No existing light-emitting diodes can be printed due to the demand for a multilayer device architecture. In contrast, the proposed devices utilize an extremely simplified single-layer device structure. Such a distinctive approach opens up a novel path towards obtaining fully printed light-emitting diodes, in which every single fabrication step may be performed by printing. The project will focus on the material chemistry and process development that will eventually lead to the manufacturing of light-emitting diode displays and light panels on both rigid and flexible substrates. Such advancements will greatly reduce the cost of light-emitting diode products, while allowing for greater energy savings in multiple application fields especially where large area and diffused light are both desired such as: solid state lighting, information displays and illuminated wallpapers. Technical: The new generation light-emitting diodes are based on organometal hybrid perovskites, an emerging class of semiconducting materials that can be readily dissolved in an organic solvent and crystalized into luminescent thin films after solvent evaporation. The perovskites are mixed with a polymer to control the crystallization dynamics and morphology of the resulting light-emitting thin films. The first research task is to optimize the nucleation and growth of light-emitting perovskite crystals in polymer matrices, and obtain the optimal perovskite morphology for light-emitting applications. The optimal morphological structure will be determined by measuring the opto-electronic properties of the composite and determining the efficiency and brightness. This will allow the characterization of relationships between different structures and properties of the materials and design scientific models to describe the compositing process. Once the structure property relations between the perovskite materials and polymers have been fully determined the results will be used as a scientific basis to make LEDs of various colors; as well as improving the environmental stability of those devices. The final step of the project will be investigating the rheological behaviors of the perovskite polymer solutions and optimize the processing techniques to produce uniform, large area light-emitting thin films. The process resolution will simultaneously be investigated to allow pixel size features to be created. This work would allow for establishing a novel type of light-emitting technology on the market. In addition the work will enhance the fundamental understanding of the structure-process-property relationship of perovskite emitters. Such knowledge is crucial for the rational design and optimization of perovskite light-emitting diodes for achieving large area and low cost displays and light panels.