Poly(2,3-dihexylthieno[3,4-b]pyrazine) via GRIM polymerization: Simple preparation of a solution processable, low-band-gap conjugated polymer

Synthesis of Poly(2,3-dihexylthieno[3,4-b]pyrazine) via GRIM Polymerization is demonstrated. The use of thieno[3,4-b]pyrazine) in conjugated polymers has been very successful in the production of low-Eg systems and are prepared via electropolymerization, resulting in insoluble materials. The reported variants of the GRIM method has successfully resulted in soluble polymeric material and the best results were found via reflux conditions that produced 50-55% of soluble pTP 2d. Analysis of the soluble fractions show identical results for both GRIM polymerized materials, and GPC data suggest that the optical properties of the GRIM protocol are identical. Initial photonic devices were fabricated from 1:1 blends of 2d and PCBM and the binary blends produced smooth films of ~90 nm thickness, and the resulting external quantum efficiency. High-purity pTPs can be produced via GRIM methods to give soluble materials with low dispersity, enhanced processability, and reduced band gaps.