π-Extented conjugated polymers entailing pechmann dye moieties for solution-processed ambipolar organic semiconductors

In this paper, we report the design, synthesis and semiconducting behavior of two conjugated D-A polymers BPDDTE and BPDBDTE which entail BPD, a Pechmann dye framework, as electron accepting moieties and (E)-1,2-di(thiophen-2-yl) ethane with and without alkyl chains as electron donating moieties. They both show very narrow bandgaps below 1.3 eV. Based on the characterization of the field-effect transistors, thin film of BPDDT exhibits ambipolar semiconducting properties with hole and electron mobilities reaching 0.245 and 0.095 cm ²·V¹·s^-1, respectively, after thermal annealing. Similarly, BPDBDTE with more alkylchains shows ambipolar semiconducting behavior with hole mobility and electron mobilities reaching 0.109 and 0.081 cm²·V^-1·s^-1. Furthermore, BPDBDTE shows good solubilities in several common organic solvents and thus is easily solution-processible. Thus, BPDBDTE is potentially processible with inkjet printing and roll-to-roll printing techniques. Two new D-A polymers (BPDBDTE and BPDDTE) with BPD as electron accepting moieties are reported. The results show that BPDBDTE with more alkyl parts shows similar ambipolar semiconducting behaviors with BPDDTE. Furthermore BPDDTE can be dissolved in common solvents at room temperature and solution-processed easily, thus this semiconducting polymer is potentially processible with inkjet printing and roll-to-roll printing techniques.