CAREER: Developing n-type low bandgap conjugated macromolecules based on aza-dipyrromethene

Case Western Reserve University, Cleveland OH

Investigators

Abstract

In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Genevieve Sauve of Case Western Reserve University will synthesize n-type, low bandgap conjugated macromolecules. The approach is to use aza-dipyrromethene (aza-DIPY) dyes as a comonomer building block, because aza-DIPYs are red-absorbers and have high electron affinities; their electronic properties also should be tunable via changes in substituents and chelation of metal ions. The aza-DIPY comonomers will be synthesized and used to preprare alternating copolymers with aryl-bis-alkynyl or aryl-bis-alkenyl units. The opto-electronic properties of the polymers will be determined, and then selected conjugated polymers will be integrated into polymer solar cells by blending them with electron-donating polymers such as poly(3-hexylthiophene). To direct nanoscale phase separation of the blend, poly(3-hexylthiophene) end-functionalized with aza-DIPY-based molecules will be synthesized and used as blending agents. Film morphologies will be analyzed and correlated with blend composition and device performance. The education plan and broader impacts of this program include: 1) implementing active-learning strategies in classroom and laboratory teaching assignments as well as incorporating solar energy conversion topics into the undergraduate and graduate curriculum; 2) mentoring and preparing undergraduate and graduate students to undertake cutting edge multidisciplinary research; and 3) serving as a role model and mentor for women students studying science and engineering. Solar cells made from electrically conducting plastics are technologically promising but suffer from low conversion efficiencies and irreproducibility in processing. This research seeks to address some of those issues by enhancing our fundamental understanding of how to synthesize new organic polymers to capture light and efficiently turn it into electrical energy. The polymers might also find application in lightweight, flexible organic electronics and display technologies.