Molecular design and ordering effects of alkoxy aromatic donor in a DPP copolymer on OTFTs and OPVs

Two p-type polymers, PONDPP and PTADPP were synthesized by Suzuki coupling reaction to investigate the effect of alkoxy aromatic donor units in diketopyrrolopyrrole (DPP)-based copolymers on OTFTs and OPVs. PONDPP containing dialkoxynaphthalene exhibits excellent field-effect performances, with a hole mobility of 0.324 cm²/V while PTADPP containing dialkoxyanthracene exhibits mobility of 4.5 × 10⁻³ cm²/V at 200 °C annealing. Bulk heterojunction type polymer solar cells based on these polymers as the electron donor materials, with PC₇₁BM as the acceptor, showed maximum power conversion efficiency (PCE) of 0.9% for PONDPP and 1.1% for PTADPP under AM 1.5 illumination. From photophysical and structural studies, we found that naphthalene unit was introduced to the DPP unit to enhance more the molecular ordering compared to anthracene unit. - Highlights: • Two diketopyrrolopyrrole (DPP)-based copolymers, PONDPP and PTADPP were synthesized. • We investigated the effect of alkoxy aromatic donor units on OTFTs and OPVs. • PONDPP and PTADTT exhibit mobilities of 0.324 and 4.5 × 10⁻³ cm²/V. • OPVs showed power conversion efficiency of 0.9% for PONDPP and 1.1% for PTADPP