New concepts for the development of active functional polymers for p and n-type OFET- applications

Here we present a concept to improve the field effect transistor performance of P3HT in terms of threshold voltage stability as well as the stability in ambient atmosphere by introducing a strong acceptor dopant in the main polymer chain. In our concept the direct introduction of the acceptor dopant in the polymer main chain ensures the strucural stability against diffusion processes. P3HTs with different contents of acceptor molecules which are fixed linked in the main chain of the polymer, have been synthesized using the McCullough Grignard metathesis method. As acceptor unit has been integrated tetrafluorbenzene (TFB). The introduced dopant amount has been varied in order to obtain an optimum between the processability of the polymers and the resultant transistor performance. Compared to the p-type semionducting polymers the n-type organic materials are markedly less developed. Recently an interesting solution to this task has been proposed in the form of a conjugate d ladder-type poly (benzo-bisimidazobenzo-phenanthroline) (BBL) showing either ambipolar or n-type field effect properties dependent upon the sample preparation and processing. However this rigid-chain ladder polymer is not soluble in the common organic solvents resulting in a rather complicated technological transfer. We report the significant improvement of the BBL-processing utilizing aqueous colloidal dispersions and their OFET-application. The resultant devices demonstrate ambipolar electronic transport with charge carrier mobilities in the range of 10-5 cm2/Vs without specific optimization procedures

n-Type Copolymers with Fluorene and 1,3,4-Heterodiazole Moieties

The successful realization of n-channel field-effect transistors requires the application of semiconducting polymers with high electron mobility (n-type). However, reports on n-type polymers are rather scarce in the literature. Therefore, the development of polymers with suitable electron transport properties is particularly challenging for the synthetic chemistry. Main chain polymers with strong acceptor units, such as 1,3,4-heterodiazoles, are potential candidates for electron transport materials in electronic devices. The fluorene unit is another ring system with interesting physical and chemical properties, which is often used in rigid-rod, main chain polymers. The present work introduces the synthesis of organo-soluble copolymers consisting of alternating fluorene-, 1,3,4-heterodiazole, and, in some cases, additional 2,5-dialkoxyphenylene units in the main chain. The reported synthesis involves modified classical polycondensation as well as the tetrazole route. We demonstrate the possibility of exchanging oxygen in the heteroaromatic ring with sulfur using Lawesson's reagent during the ring closure reaction. An alternative structure of the heterocyclic ring with N-phenyl in the oxygen position is feasible using the tetrazole synthetic route. The chemical and electrochemical properties of the copolyfluorenes are investigated in detail. Some of the synthesized copolyfluorenes have also been used for the preparation of electron-only devices enabling the calculation of the electron mobilities. Further, an organic field-effect transistor (OFET) characteristic was shown

Dispersionen steifkettiger, konjugierter Polymere, Verfahren zu deren Herstellung und deren Verwendung zur Herstellung elektronischer Bauelemente

DE 10325102 B UPAB: 20040611 NOVELTY - Dispersions of rigid-chain, conjugated, organic solvent-insoluble polymers (I) in an aqueous, organic or aqueous organic dispersion medium (II), in which the size of the dispersed (I) particles is in the 100-800 nm range, are claimed. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a process for producing a dispersion of (I) in (II) by (a) producing a solution of (I) in a strong acid or in a liquid mixture containing a Lewis acid and (b) adding this solution to an aqueous surfactant solution to give a (I) dispersion. USE - The dispersion is used for producing a thin film of a rigid-chain, conjugated polymer or an electronic device, preferably FET, organic LED or photovoltaic cell (all claimed). ADVANTAGE - The semiconducting and other properties of rigid-chain, conjugated polymers make them of interest as active materials for electronic devices. However, an existing method of making thin films from the ladder polymer poly(benzobisimidazobenzo-phenanthroline) (BBL) is very costly and not practical for technical use. The present process converts the polymers into a form suitable for processing and especially for producing thin films

Thermoluminescence and electroluminescence of annealed polyfluorene layers

As-prepared and annealed layers of polyfluorene were studied by thermoluminescence (TL), photoluminescence (PL) and electroluminescence (EL). Upon annealing at the transition to the liquid-crystalline phase, the green emission in PL and EL becomes more pronounced. At the same time the TL spectrum broadens towards higher temperatures, indicating the introduction of additional trapping sites. In contrast, photooxidation does not broaden the TL spectrum, even so it significantly affects the emission spectra. We conclude that annealing causes the formation of non-/weakly emitting aggregates which compete with the undisturbed chains with respect to charge carrier capture and exciton recombination

The influence of the mixture of vermicompost and sulphur-perlite-containing waste on the yield and the quality of crops

Any type of material that increases soil yield, both qualitatively and quantitatively, to strengthen the soil and increase its fertility is called fertilizer. The current study examines the production of a new effective fertilizer. Results presented involve effects of new bioorganic-mineral compositions obtained from the combination of vermicompost and sulphur-containing waste from sulphuric acid production on the yield and quality of tubers (beets, carrots). An increase in the yield of tubers has been found to be 1.13–1.25 times when the bioorganic-mineral composition (~20 Mg∙ha–1) is introduced into the sierozem (serozem) soil. The best results are obtained with mass ratios in the range 30–45 and 55–70 for vermicompost and sulphur-perlite-containing waste, respectively. The effectiveness of the mixture of vermicompost and sulphur-containing waste is explained by the increased synergistic interaction of these components. The proposed composition has high structure-forming, water-retaining, nutritional and biologically active properties