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DS: Fachverband Dünne Schichten
DS 22: Focussed Session: Inorganic/Organic Semiconductor Hybrid Structures I (jointly with HL and O)
DS 22.6: Talk
Tuesday, March 15, 2011, 12:45–13:00, POT 151
Electrical investigations of different polymer and substrate materials for dye-sensitized ZnO-NW/polymer hybrid solar cells — •Kay-Michael Günther1, Julia Waltermann1, Stefan Kontermann2, and Wolfgang Schade1,2 — 1Clausthal University of Technology, EFZN, EnergieCampus, 38640 Goslar — 2Fraunhofer Heinrich-Hertz-Institute, EnergieCampus, 38640 Goslar
Dye-sensitized solar cells composed of a n-doped ZnO nanowire (NW) array and a p-doped polymer layer appear to be a promising candidate for low-cost production of environment-friendly solar cells. In this study, we compare the commonly used polymer layers PEDOT:PSS and P3HT. While the former one provides a better conductivity, the latter one shows itself a photoabsorbance below λ = 400 nm. In addition, we investigate three different TCO substrates (ITO, FTO and ZnO:Al) using Impedance Spectroscopy (IS), current-voltage-measurements (IV), as well as IV-transients. The results show that in our setup an additional polycrystalline ZnO layer beneath the ZnO NWs is needed to prevent short circuits caused by polymer seeping between the NWs towards the counter electrode. Furthermore, the confinement to a simple ZnO layer enables us to optimize the polymer layer independently from the NWs. Hence, we compare devices with and without NWs and with different processing parameters. We achieve the best results with P3HT and FTO substrates. With ZnO:Al, we observe additional RC-combinations which partly result from a Schottky barrier formed at the ZnO:Al interface leading to a significant higher series resistance. An equivalent circuit is derived and discussed.