Charge Carrier Transport in Non-Homogeneous MDMO-PPV Polymer

V. Kažukauskas, M. Pranaitis and V. Janonis Department of Semiconductor Physics and Institute of Applied Research, Vilnius University, Saulėtekio 9, bldg. 3, LT-10222 Vilnius, Lithuania

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By thermally stimulated currents we have investigated carrier transport and trapping in [poly-(2-methoxyl, 5-(3,77dimethyloctyloxy)] paraphenylenevinylene (MDMO-PPV). To assure selective excitation of the defect states the spectral width of the exciting light was varied from 1.77 eV up to 3.1 eV. The thermally stimulated current curves were shown to be a superposition of carrier generation from trapping states and thermally stimulated mobility growth. The extrinsic excitation resulted in 0.16 eV photoconductivity effective activation energy values, which decreased down to 0.05 eV for the intrinsic excitation. The deeper states with activation energies of 0.28-0.3 eV and 0.8-0.85 eV were identified, too. The results are direct indication of distributed in energy trapping and transport states with the standard deviation of the density of states of about 0.015 eV.

DOI: 10.12693/APhysPolA.119.128 PACS numbers: 73.20.Hb, 73.50.Gr, 73.50.Pz, 73.61.Ph