Mechanical Behavior of Polymer-Fullerene Blends for Photovoltaic Applications

This grant provides funding to study relationships between the mechanical behavior and optoelectronic performance of polymer-fullerene blend films for photovoltaic device applications, i.e. solar cells. The principle investigators will consider how morphological features of the blend film affect both the mechanical and electrical properties of the active layers, and how these properties are coupled and modified through material selection and processing conditions. A focus will be on characterizing the mechanical properties and the physical mechanisms of performance variation in devices for different deformation modes. To analyze this system, a combination of experimental and computational investigations will be conducted. The experimental research will combine thin-film mechanics and optoelectronic device measurements along with detailed morphological characterization. A micromechanical model will be developed based on a multi-phase model consisting of pure polymer and fullerene phases, and a miscible phase. A non-linear finite element method will then be applied to integrate the component models.

Organic solar cells based on polymer-fullerene heterojunctions are a promising technology to provide renewable energy that is cost competitive with fossil fuel sources. Critical to the commercial success of this technology is the ability to flex the solar cell during both fabrication and operation. If successful, this research will help guide the development of highly flexible and durable organic solar cells with improved performance over current state of the art devices. Determining the fundamental relationships between the mechanical and electrical properties of the polymer-fullerene film will also provide new insights into the role of film morphology in the energy conversion process and suggest processing strategies that maximize device performance. In addition to the research findings, graduate students involved in the grant will be trained in a highly interdisciplinary research environment. The principle investigators will also contribute to an engineering summer camp for high school students that focuses on solar power technologies.