Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 45: Joint Poster Session

HL 45.1: Poster

Tuesday, March 15, 2011, 18:00–21:00, P1

Investigation of the built-in voltage in organic pin solar cells using electroabsorption spectroscopy — •Ellen Siebert-Henze, Wolfgang Tress, Vadim G. Lyssenko, Susanne I. Hintschich, Karl Leo, and Moritz Riede — Institut für Angewandte Photophysik, Dresden, Deutschland

The built-in voltage of small molecule organic solar cells based on the pin concept is investigated. We use the method of electroabsorption spectroscopy whose principle is the detection of absorption changes due to electrical excitation (Stark effect). A voltage consisting of a DC and an AC part is applied to the sample and the change in absorption is detected using a lock-in amplifier. The variation of the applied DC voltage modifies the DC field across the sample leading to a linear change of the corresponding Stark signal. This supplies information about the built-in voltage of the device which is determined for different combinations of donor materials and hole transport materials (MeO-TPD, BPAPF, alpha-NPD, and ZnPc). In addition, the doping concentration of the hole transport layer is modified and the influence of the consequential change of the work function on the built-in voltage is examined. It is shown that both the short-circuit current as well as the fill factor increase for larger built-in voltages.