Dresden 2009 – scientific programme

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SYOP: Symposium Organic Photovoltaics: From Single Molecules to Devices

SYOP 4: Organic Photovoltaics: from Single Molecules to Devices

SYOP 4.19: Poster

Thursday, March 26, 2009, 16:30–19:00, P1A

Efficiency increase of two-step-sensitized inorganic / organic hybrid absorber materials — •Eric Mankel, Thomas Mayer, and Wolfram Jaegermann — Technische Universität Darmstadt, Materials Science Institute, Surface Science Division, Petersenstraße 23, 64287 Darmstadt

Photovoltaic third generation concepts promise a significant increase of energy conversion efficiency. Two-step sensitization of inorganic wide band gap matrices by incorporated organic donor-acceptor molecules (e.g. dyads) has been suggested as possible means of creating third generation absorbers. Based on the model of Shockley and Queisser we calculate the rise of the ultimate efficiency and the detailed balance limit of a sensitized p-n-junction by adding a sensitization current provided by the organic molecules to the photocurrent provided by the matrix material. The model includes the dependence of a number of parameters namely the band gap of the matrix material, the energetic position of the organic frontier orbitals relative to the matrix band edges, the lifetime of the first excited molecular state and the Gaussian width of the absorption curve of the dye. For a width of 0.25eV an overall maximum efficiency of 45% has been calculated. To reach this limit under AM1.5 conditions the lifetime of the excited state must be longer than 10ms. Finally the calculations have been applied on ZnSe / CuPc / PTCDA composites using the band alignment as experimentally determined by XPS/UPS measurements.