Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 35: Joint Session: Organic Semiconductors II: Solar Cells B

HL 35.3: Talk

Tuesday, March 15, 2011, 11:15–11:30, ZEU 222

Sub-Bandgap Absorption in Polymer-Fullerene Solar Cells — •Martin Presselt¹, Felix Herrmann¹, Marco Seeland¹, Maik Bärenklau¹, Roland Rösch¹, Wichard J. D. Beenken², Erich Runge², Sviatoslav Shokhovets¹, Harald Hopp¹, and Gerhard Gobsch¹ — ¹Experimental Physics I, Institute of Physics & Institute of Micro- und Nanotechnologies, Ilmenau University of Technology, Weimarer Str. 32, 98693 Ilmenau, Germany — ²Theoretical Physics I, Institute of Physics, Ilmenau University of Technology, Weimarer Str. 25, 98693 Ilmenau, Germany

We present external quantum efficiency (EQE) studies of P3HT:PCBM based bulk heterojunction polymer solar cells with improved intensity resolution in the sub-bandgap (SBG) region, i.e. the energy range below the optical bandgaps of the pristine materials. Varying the P3HT:PCBM blending ratio, we find that in addition to a Gaussian profile an exponential tail is needed for a quantitative description of the SBG EQE spectra. To gain insights into the origin of the single contributions, absorption and emission spectra covering several decades of intensity and SBG EQE signals are discussed in detail.