Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 24: Poster: Organic Semiconductors
CPP 24.7: Poster
Mittwoch, 28. März 2012, 11:00–13:00, Poster A
Contact and injection properties of organic planar heterojunction solar cells studied by transient current methods — •Lena Reichardt, Ulrich Hörmann, and Wolfgang Brütting — Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
Contact properties and charge carrier injection behavior of organic planar heterojunction solar cells have been investigated by means of complementary transient current methods. Charge extraction by linearly increasing voltage (CELIV) at different initial DC bias and impedance spectroscopy (IS) reveal that, depending on the contact properties, injection either of both charge carrier types at the same time or of one type prior to the other one may occur. This corresponds to the injection behavior of poly(3-hexylthiophene)/fullerene (P3HT/C60) and P3HT/diindenoperylene (P3HT/DIP), respectively with PEDOT:PSS and BCP/Al as contacts. Both CELIV and steady state measurements on P3HT/C60 directly indicate injection currents in forward direction. By contrast, measurements on P3HT/DIP result in transient current signals of CELIV measurements at bias voltages where no injection current is seen in steady state measurements. The presence of injected charges in both cases is confirmed by IS which exhibits a change in device capacitance with bias voltage. The ability to deliberately influence the presence of injected charges by contact modification might be helpful to determine the mobility of a specific charge carrier type by (dark) CELIV or to prevent unfavorable injection under forward bias in photo-CELIV measurements.