Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 65: Poster: Organic electronics and photovoltaics (CPP; jointly with HL, O)
HL 65.8: Poster
Mittwoch, 13. März 2013, 16:30–18:30, Poster C
Probing charge carrier dynamics in organic solar cells based on merocyanines — •Steven Graf1, Martin Lenze1, Julian Krumrain1, Dirk Hertel1, Klaus Meerholz1, and Frank Würthner2 — 1Department für Chemie, Universität zu Köln, Luxemburger Straße 116, 50939 Köln — 2Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg
Organic photovoltaics offer a very promising green energy alternative. Highly efficient organic solar cells can be produced by cost-effective methods such as coating from solution (SOL) or depositing under high vacuum conditions (VAC). In our approach we investigate merocyanines (MC), a class of low-molecular-weight colorants, as donor material in organic BHJ solar cells. These molecules are processable via both deposition techniques showing remarkable power conversion efficiencies (PCE) beyond 4% for SOL- and 6% for VAC-processed devices. Towards even higher PCEs it is mandatory to obtain a better insight into fundamental charge carrier processes such as generation, transport and recombination. We use steady state and time resolved photoluminescence spectroscopy to examine charge-transfer (CT) states in pure and blended merocyanine thin films. The role of these CT states in solar cells is further studied by field and temperature dependent measurements of the external quantum efficiency (EQE). By varying processing conditions as well as blend compositions the influence of morphology on the solar cells is illustrated. The investigations are supported by temperature and electric field dependent studies of charge recombination and transport via photo-CELIV technique.