CAREER: Engineering and Integration of Polymer Electronic Materials for Alternative Energies

Drexel University, Philadelphia PA

Investigators

Abstract

0846245 Lau Intellectual merit: With the increasing need for clean, alternative energies, the sun represents a vast sustainable source. Polymer-based solar cells are seen as an answer that would permit more widespread solar harvesting. However, the performance of polymer-based solar cells has been less than optimal. In bulk heterojunction devices, inefficiencies result from the mismatch of high band gaps of conjugated polymers with the solar spectrum, and generally poor charge generation and charge transport due to structural and morphological defects. Efforts at lowering band gap and improving material properties have been met with challenges in liquid-based processing, such as polymer intractability, solution-induced changes, restrictive synthesis routes, and solvent incompatibilities. In dye-sensitized devices that utilize nanocrystalline titania, inefficiencies result from poor infiltration of polymer electrolytes into the mesoporous titania due to poor wettability and liquid viscosity with polymer solution processing. New processing methods which overcome these problems while preserving the ability to carry out materials design and synthesis could lead to significantly enhanced solar cell performance. This CAREER project aims to bring a new paradigm to polymer thin film processing, and build on the scientific, educational and human resources needed to bring greater solar energy awareness and adoption. The research program aims to make use of initiated chemical vapor deposition (iCVD) technologies to design, synthesize and integrate polymer electronic materials as viable photovoltaic devices. In a single step, iCVD will enable the chemical synthesis and physical deposition of a solid polymer thin film on a substrate by thermally initiating the polymerization of a monomer vapor. By circumventing the liquid phase, solvent-related issues will be avoided. More importantly, iCVD will provide significant freedom in performing advanced materials design through copolymerization, click chemistry and tailored monomers. The specific research aims are to (1) engineer polymer electronic materials as viable photovoltaic materials, (2) integrate polymer electronic materials to create efficient and robust photovoltaic devices, and (3) establish critical processing relationships and reaction mechanisms to enable optimization of solar cell performance. Broader impact: Integrated with the research is an educational program which aims to train future scientists at the graduate and undergraduate levels in photovoltaics technology, and engage Philadelphia high school students and teachers through energy education and solar test stations that will provide students with opportunities to evaluate the long term performance and stability of fabricated solar cells. Additionally, the program will immerse promising high school students from area high school partnerships and Drexel's summer mentorship program in a research experience on materials processing that intends to strengthen interest in science and technology. Minority, underprivileged and underrepresented students will be actively recruited. Further, a new thin films processing course with a focus on photovoltaics and electronics fabrication will be established to further the undergraduate and graduate energy curriculum. Ultimately, this project is motivated by the long term goal of discovering novel environmentally responsive and responsible solutions. Efforts from this work will deliver solutions, knowledge and resources for energy independence, and help build a sustaining scientific program in materials design and processing that will extend beyond alternative energies into emerging areas of biomedicine, fuel cells, energy storage and flexible electronics.