Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 19: Organic photovoltaics and electronics - mostly properties of the absorber (with DS)
HL 19.2: Talk
Monday, March 16, 2015, 17:15–17:30, EW 202
Unified model approach for hybrid charge transfer states in organic-organic heterostructures — Tino Meisel, •Paul Beyer, Georg Heimel, Norbert Koch, and Andreas Opitz — Humboldt-Universität zu Berlin, Germany
There are different electronic coupling mechanisms for organic-organic heterostructures, which ultimately determine the charge separation in solar cells or the doping efficiency in blended systems. Here, these charge transfer mechanisms are investigated in blends of diindenoperylene (DIP) with different acceptor materials, namely core functionalized perylene alkyldiimide with cyano groups (PDIR-CN2) and perfluoronaphthalene-diylidene dimalononitrile (F6TCNNQ), which show compatible optical gaps. To scrutinize the interplay between these molecules a combination of atomic force microscopy (AFM), UV/Vis/NIR absorption spectroscopy and electrical conductivity measurements is used.
From absorption spectroscopy the formation of new absorption features is clearly seen in blends with both acceptors. An increase in electrical conductivity is observed for DIP:F6TCNNQ blends, which is absent in the DIP:PDIR-CN2 case. The formation of distinct islands in AFM shows a difference in morphology between pristine and blended films. From these investigations we conclude the appearance of new charge transfer states and a unified hybridization model is applied to explain the different regimes of charge transfer behavior.