We study the fundamental chemistry and physics of polymeric functional nanomaterials, and engineer them to apply in various fields such as sensors, catalysts, and emulsion-based technology. In addition, we have interest in solution processable electronics such as organic solarcells and LEDs. The main themes we have aimed are listed below.
■ Polymeric Functional Nanomaterials
The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous optical, magnetic or mechanical properties. In addition to the conventional role of hybrid materials, nanoparticles with specifically designed functional groups can be integrated for advanced nanotechnology applications to precisely control their architecture and function. The addition of inorganic nanoparticles to block copolymers provides a route for the fabrication of novel functional materials such as photonic band gap materials, highly efficient catalysts, chemical and biological sensors, and high density magnetic storage media.
The properties of such functional materials can be dramatically enhanced by precise control of inorganic nanoparticles with nanolength scales. For example, particles at the interfaces between two different polymers can be used as nano-surfactants to produce new materials that cannot be easily achieved by conventional approaches. In long term research goal, we will develop a general scaffold for the design of novel functional nanomaterials from building blocks of organic and inorganic particles and/or nanorods. The key step is judicious selection of organic shells to enhance the functionality of inorganic core, thus leading to their integrations to 3D novel functional devices.
■ Solution Processable Electronics (Organic Solar Cells and LEDs)
Organic solar cells have attracted a great deal of attention based on the potential for realizing low-cost, solution processable, and flexible solar cells. Among approaches to organic solar cells, solution processable polymers most closely embody this vision based on the variety of processing methods that can be employed (e.g., spin-coating, screen printing, ink-jet printing). In addition, the properties of conjugated polymers having very light absorption coefficients can be easily tuned simply by modifying structures. In the current state-of-the-art polymer photovoltaics (~10% in power efficiency), blends of electron donating conjugated polymers and small molecule fullerene derivatives are used as the active layer of bulk-heterojunction (BHJ) devices where the two components are cast together to form a blended morphology. Being able to control the initial and long-term phase segregation on the nanoscale between the two materials is dependent on the miscibility of the two components.
The goal of our project is to develop a fundamental understanding between the chemical and physical modification of conjugated organic/polymer nanomaterials on the molecular level and their performance in energy-related applications such as polymer photovoltaics, and organic light emitting diodes. Particularly, we will focus to understand the molecular orientations and interactions at the interfaces between electron donors and acceptors and develop new materials having lower band gap with higher light absorptions as well as enhanced air, mechanical and thermal stabilities and thus overcome the critical hurdles for commercialization of polymer solar cells. In particular, considering all of the potential applications of the PSCs as printable and portable devices on the flexible substrate, the importance of enhancing the mechanical properties of the PSCs will be greatly amplified. As solution, we are working on developing all polymer solar cells that have dramatically enhanced mechanical properties.
Bumjoon Kim (김범준)