While p-channel semiconducting polymers have been widely investigated during recent years; it continues to be a challenge to identify stable, solution processable electron tranport polymer materials, due issues associated with stabilization of the LUMO energy level. This level could be governed via incorporation of electron deficient units which reduce the electron density of polymer semiconductors. Herein, we introduce a new polymer, poly(bithiazole-bithiophene-diketopyrrolopyrrole), PDBTz, synthesized via Stille polycondensation. In comparison to the previously reported hole transport material, poly(tetrathiophene-diketopyrrolopyrrole), PDBTz, in which one bithiophene is replaced by bithiazole, is strictly an electron transporting pi-conjugated polymer. Thus, it is now possibile to realize the conversion of p- to n-channel polymer semiconductors through simply replacing a few electron rich units by ones that are electron deficient. The 5-decylheptadecyl side chain, which has been demonstrated to facilitate both polymer solubility and effectivet p-p intermolecular interactions, has been incorporated into PDBTz, allowing solution-processing onto organic electronic and optoelectronic devices from a wide range of solvents, including the non-halogenated and lower-toxicity o-xylene and toluene. PDBTz exhibits field-effect electron mobilities in a range of 0.2 to 0.9 cm2V-1s-1, depending on choice of gate dielectric, source-drain electrodes, and architecture. Upon encapsulation, PDBTz based field-effect transistors exhibit no change in electron mobility, current on/off ratio and threshold voltage after exposure to ambient conditions for more than 4 days (under continued investigation). PDBTz represents a viable acceptor material for all-polymer solar cells and a possible candidate for organic thermoelectrics.

High performance, solution-processable, electron transport polymer semiconductor based upon bithiazole and diketopyrrolopyrrole

248th National Meeting (2014)

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