GIWAXS measurements confirm end-on alignment for TPD-copolymers obtained from Stille polycondensation using fluorinated and non-fluorinated comonomers.

The design, synthesis, characterization, and application of a novel series of copolymers based on the electron deficient thieno [3,4-c]pyrrole-4,6-dione building block, copolymerized with either thieno[3,2-b]thiophene (PTPDTT) or thiophene (PTPDT), are reported. High molecular weights were obtained for PTPDTT via Stille polycondensation. For the PTPDTs, different molecular weights were achieved by varying the polymerization conditions. The increase in molecular weight (PTPDT-2) favors face-on alignment and increases the charge carrier mobility. Grazing-incidence wideangle X-ray scattering measurements reveal higher crystallinity for PTPDTT with up to 5 orders of lamellar stacking compared to PTPDTs. All polymers show ambipolar charge transport with highly balanced hole and electron mobilities in organic field effect transistors (OFETs), which improve considerably upon thermal annealing. A shift of comonomer from simple thiophene in PTPDT-2 to planar and electron-dense thienothiophene in PTPDTT drastically changes the alignment from face-on to edge-on fashion. Consequently, the charge carrier mobility increases considerably by 1 order of magnitude in PTPDTT, reaching excellent charge carrier mobilities for both holes (0.11 cm 2 V −1 s −1 ) and electrons (0.17 cm 2 V −1 s −1 ). PTPDTT was tested as a donor material in combination with PC 71 BM as well as an acceptor material along with a donor polymer. As a donor material, a power conversion efficiency of 4.3% was reached in combination with PC 71 BM.

A thin film of polystyrene has been doped with small amounts of dithienylcyclopentene (DCP) based molecular switches and perylene bisimide (PBI) chromophores to obtain a photoswitchable smart matrix. The photochromic DCP can be converted by light between two bistable conformations and thereby changes the energetic position of its lowest excited singlet state. We exploit this feature to regulate the transfer of excitation energy between PBI and DCP as a function of the externally controllable illumination conditions in such a blend.