Regensburg 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 62: Poster II: Photovoltaics and Organic Semiconductors
HL 62.7: Poster
Donnerstag, 25. März 2010, 18:00–20:00, Poster D2
Dissociation of singlet excitons in PPV derivatives with varying dielectric constant — •Julia Kern1, Michael Binder1, Markus Mingebach1, Andreas Baumann1, Carsten Deibel1, and Vladimir Dyakonov1,2 — 1Experimental Physics VI, Physical Institute, Julius-Maximilians-University of Würzburg, Am Hubland, D-97074 Würzburg — 2Center for Applied Energy Research (ZAE Bayern e. V.), Am Hubland, D-97074 Würzburg
In bulk heterojunction solar cells, the low relative permittivity of conjugated polymers such as poly (p-phenylene vinylene) (PPV) is considered to be a limiting factor of the charge separation process. The lower the dielectric constant, the stronger the bond of the primary photoexcitations, i.e., singlet excitons. Here, we investigate the influence of the relative permittivity on the exciton binding energy. For this purpose, three PPV derivatives exhibiting similar charge carrier mobilities but different relative permittivities of 3.0, 4.0 and 5.5, respectively, are characterized by means of external quantum efficiency and field dependent photoluminescence measurements. We discuss our experimental results in terms of the two-step dissociation process from exciton via polaron pair to polarons as well as the impact on solar cell performance.