Search

Your search keyword '"Namdas, E. B."' showing total 18 results
Start Over Author "Namdas, E. B."
18 results on '"Namdas, E. B."'

11. Solution-Processed n-Type Organic Field-Effect Transistors With High ON/OFF Current Ratios Based on Fullerene Derivatives.

Author

Tiwari, S. P., Namdas, E. B., Rao, V. Ramgopal, Fichou, D., and Mhaisalkar, S. G.

Subjects
ORGANIC field-effect transistors, ORGANIC semiconductors, HOPPING conduction, FULLERENE thin films, SEMICONDUCTORS, ELECTRON mobility, THERMAL properties, ELECTRIC currents, NANOTECHNOLOGY
Abstract

Solution-processed n-type organic field-effect transistors (OFETs) based on the fullerene derivative {6}-1-(3-(2- thienylethoxycarbonyl)-propyl)-{5}-1-phenyl-[5,6]-C61 (TEPP) and phenyl-C61-butyric acid methyl ester (PCBM) in a multiring source/drain structure are reported. Devices with TEPP show high electron mobility up to 7.8 × 10-2 cm2/Vs in the saturation regime for bottom-contact OFETs with Au S/D electrodes with a solution-processed fullerene derivative. The ON/OFF ratios reported in this letter, which are in the range of 105 - 106, are among the highest values reported for such devices. This mobility is always higher compared to PCBM devices prepared in identical conditions. The mobility of TEPP and PCBM increased with increasing temperatures in the range of 100-300 K with activation energy of 78 and 113 meV, respectively, which suggests that the thermally activated hopping of electrons is dominant in TEPP. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

12. Intra- and Interchain Luminescence in Amorphous and Semicrystalline Films of Phenyl-Substituted Polythiophene

Author

Ruseckas, A., Namdas, E. B., Ganguly, T., Theander, M., Svensson, M., Andersson, M. R., Inganas, O., and Sundstrom, V.

Abstract

We report time-resolved photoluminescence (PL) measurements of spin-cast amorphous films of a regioregular polythiophene derivative poly[3-(4-octylphenyl)thiophene] and of annealed semicrystalline films of the same polymer with an interchain stacking distance of 5 Å. Red-shifted PL appears at long delay times in both pristine and annealed films, which we assign to interchain aggregates populated by excitation energy migration. Aggregate luminescence in annealed films exhibits a pronounced vibronic structure indicating the coupling to a C&dbd;C bond stretch with a Huang−Rhys factor S = 2. Two types of aggregates are distinguished in annealed films:  in a few picoseconds most excitations are trapped by aggregates with a large energy gap (about 1.83 eV) between the lowest excited singlet state and the ground state. Excitation energy is transferred or the aggregates relax structurally with a time constant of about 200 ps to aggregates with a smaller energy gap (about 1.75 eV). The radiative lifetime of aggregates with smaller energy gap is estimated to be about 35 ns, two times longer than that of aggregates with the larger energy gap. In spin-cast amorphous films, emission from intrachain singlet excitons has a longer lifetime than in annealed films and only high-energy-gap aggregates are populated.

Published
2001

Catalog

Books, media, physical & digital resources
See catalog results