Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 14: Poster I
HL 14.48: Poster
Montag, 24. März 2003, 17:00–19:30, HSZ/P2
Pyronin B as a donor for n-type doping of organic thin films — •Fenghong Li1, Ansgar Werner1, Kentaro Harada1, Martin Pfeiffer1, Susanne Machill2, Torsten Fritz1, and Karl Leo1 — 1Institut für Angewandte Photophysik; TU Dresden; 01067 Dresden — 2Institut für Analytische Chemie; TU Dresden; 01067 Dresden
We present a stable n-type doping of organic matrices using cationic dyes such as rhodamine B or pyronine B. Conductivities up to 10−4 S/cm and 10−5 S/cm, respectively, can be obtained for naphtalene tetracarboxylic dianhydride NTCDA and perfluorinated zinc phthalocyanine F16–ZnPc doped with about 2% of pyronine B. For F16–ZnPc, the conductivity is increased by up to 6 orders of magnitude upon doping compared to the undoped state accompanied by a drop in activation energy from 0.91 eV to 0.33 eV. Field effect measurements prove the n-type conduction. UV-Vis and FTIR spectroscopy confirms the donor properties of Pyronin B: We find pyronine B mostly in its reduced colorless state when doped into weak acceptor-type matrices like NTCDA. This finding is in agreement with the electrical charactization that suggests that reduced pyronine B forms a deep donor state. However, the colored cationic state appears for pyronine B in tetracyanoquinodimethane TCNQ or whenever doped layers are exposed to oxygen. Mass spectroscopy gives insight in the evaporation mechanism of the organic salt pyronin B chloride.