Synthesis and characterizations of poly(3,6-thienophenanthrene) and poly(2,7-thienophenanthrene) and their applications in polymer light-emitting devices and solar cells

•Poly(3,6-thienophenanthrene) and poly(2,7-thienophenanthrene) were synthesized.•The obtained polymers were found to be liquid-crystalline.•PSCs based on copolymer from 2,7-thienophenanthrene showed a PCE of 3.5%.

Here we report the synthesis of two novel phenylene-based polymers-poly(3,6-thienophenanthrene) (PTP36) and poly(2,7-thienophenanthrene) (PTP27) via base-free Suzuki–Miyaura reaction. The structure and electroluminescent properties of the meta-linked PTP36 and para-linked PTP27 are fully characterized. The obtained polymers were found to be liquid-crystalline, with broad band gap of 2.72 eV and 2.49 eV, respectively, which are much smaller than those of corresponding polyphenanthrenes. On the basis of PTP36 and PTP27, copolymers of 2,7-thienophenanthrene and 3,6-thienophenanthrene with 5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)benzothiadiazole (DBT), namely PTP36-DBT and PTP27-DBT were prepared and be investigated as a potential donor material for polymer solar cells. The preliminary data show that the maximal power conversion efficiencies (PCEs) of the PTP27-DBT- and PTP36-DBT-based polymer solar cells are 3.5% and 0.9%, respectively.

Graphical abstractSynthesis and opto-electronic properties of poly(3,6-thienophenanthrene) PTP36 and poly(2,7-thienophenanthrene) PTP27 based on a new thienophenanthrene monomer was reported. These two thiophene-fused phenanthrene based polymers exhibit wider absorption range compared with polyphenanthrenes and polypyrenes. 2,7-Thienophenanthrene copolymers with 5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)benzothiadiazole (DBT) exhibit promising potential as electron donor materials for polymer solar cell, which show a PCE of 3.5%.Figure optionsDownload full-size imageDownload as PowerPoint slide