Surface Energy Modification of Semi-Random P3HTT-DPP.

Abstract

Alkyl solubilizing side chains on conjugated polymers can serve as a handle for modifying polymer properties. Recently, oligo-ether and semifluoro alkyl side chains were utilized to tune the surface energy of random P3HT-based polymers without changing the optical and electronic properties. Here, this method is applied to semi-random poly(3-hexylthiophene-thiophene-diketopyrrolopyrrole) (P3HTT-DPP) and the subsequent polymer device, optical, electronic, structural, and thermal properties are characterized. P3HTMETT-DPP, bearing oligo-ether side chains, exhibited higher crystallinity, closer lamellar packing, and lower temperature thermal transitions. P3HTFHTT-DPP, featuring semifluoro alkyl side chains, presented reduced crystallinity, greater lamellar packing distances, and higher temperature thermal transitions. P3HTMETT-DPP performed similarly to P3HTT-DPP under identical processing conditions, whereas P3HTFHTT-DPP had greatly reduced JSC due to lower polymer concentration necessitated by solubility.