EAGER: Electropolymerized Layers with Tuned Light Absorption and Charge Transport Properties

This EArly-concept Grants for Exploratory Research (EAGER) grant provides funding for the development of electropolymerized light absorbing layers and charge transfer complexes between semi-conducting polymers and functionalized carbon nanotubes. These materials and structures are targeted towards use in thin-film organic photovoltaics, a technology that may enable deployment of inexpensive, flexible photovoltaic modules for a wide range of applications. In this project, monomers with low solubility but advantageous light absorption properties will be electropolymerized to form 50-300 nm films. Electrodeposition of soluble monomers can induce high pi-pi stacking order normal to the electrode surface which creates favorable molecular alignment for thin, light-absorbing films. The films will be interrogated for their optical and charge transport properties and processing-structure-property relationships will be developed to guide the fabrication of high performance films that have broad-spectrum light absorption and high charge mobility. Porous carbon nanotube mats will be impregnated with electrodeposited polymer to create donor-acceptor assemblies. The nanotubes may be surface-functionalized to tune the energy level differences between the polymer electron donor and nanotube electron acceptor for efficient charge transfer between phases, a critical step in the operation of organic photovoltaics.

If successful, the results of this research will lead to improvements in organic photovoltaic active layer processing and a deeper understanding of the optical and electrical properties of electropolymerized polymers. The primary goal of this work is to determine the potential of a new processing method for photovoltaic active layers and to measure the key light absorption and charge transport attributes of these materials. Determining the process parameters and critical materials properties to achieve the objectives of this work will help to reduce the cost and widen the possible materials set for organic photovoltaic devices. The work will also contribute to fabrication of optoelectronic thin films for other applications such as polymer electronics.