Effect of Molecular Orientation, on Photovoltaic Efficiency, and Carrier Transport, in a New Semiconducting Polymer

V. Kažukauskas a, M. Pranaitis a, C. Sentein b, L. Rocha b, P. Raimond b, I. Duyssens c, I. Van Severen c, L. Lutsen c, T. Cleij d and D. Vanderzande c, d a Department of Semiconductor Physics, and Institute of Materials Science and Applied Research, Vilnius University, Saulėtekio al. 9, bldg. 3, LT-10222 Vilnius, Lithuania b DRT-LITEN-DTS-LCS, b^at.451, CEA Saclay, F-91191 Gif-sur-Yvette, France c IMEC-IMOMEC Division, Wetenschapspark 1, B-3590 Diepenbeek, Belgium d Hasselt University, Agoralaan 1, SBG/OS department, B-3590 Diepenbeek, Belgium

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Received: 26 08 2007;

New functionalized soluble poly(p-phenylene vinylene) derivative bearing polar molecules was designed and synthesized in order to investigate effects of molecular orientation in polymer photovoltaic devices. The active polar molecule is the 4-(N-butyl-N-2-hydroxyethyl)-1- nitro-benzene group. The grafting of the push-pull molecule with a donor/transmitter/acceptor structure, possessing a large ground state dipole moment, enables the molecular orientation by a dc electric field. An internal electric field stored in such system facilitates exciton dissociation and improves charge transport in single-layer devices. In our systems an increase in the external quantum efficiency by a factor of about 1.5 to 2 is estimated. The associated effects of orientation on the carrier injection and transport properties were evidenced.

DOI: 10.12693/APhysPolA.113.1009 PACS numbers: 73.50.-h, 81.40.Rs, 81.40.Tv, 73.61.Ph