Alternating Copolymers Containing Bithiophene and Dialkoxynaphthalene for the Applications to Field Effect Transistor and Photovoltaic Cell: Performance and Stability

Poly(5',5 ''-bithiophene-alt-2,6-[(1,5-didecyloxy)naphthalene]) (PBDN) was synthesized from 2,6-dibromo-1,5-didecyloxynaphthalene and 1,1'-[2,2'-bithiophene]-5,5'-diylbis[1,1,1-trimethylstannane] and was used as the active layer in organic thin-film transistors (OTFTs) and organic photovoltaic cells (OPVs). The obtained PBDN was soluble in organic solvents such as chloroform, chlorobenzene, and toluene and had a weight-averaged molecular weight of 9100, with a poly-dispersity index of 1.31. The photoluminescence (PL) maximum of the polymer was found at 500 and 530 nm in solution and at 567 nm in the film state, respectively. The highest occupied molecular orbital (HOMO) level of PBDN was low (-5.38 eV, ultraviolet photoemission spectroscopy and cyclic voltammetry), and the solution-processed thin-film transistors (TFTs) prepared using this polymer only showed a minimal change in their performance (