Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 14: Poster I

HL 14.46: Poster

Montag, 24. März 2003, 17:00–19:30, HSZ/P2

Numerical simulation of organic solar cells — •Fryderyk Kozlowski, Martin Pfeiffer, Jens Drechsel, Bert Maennig, Desta Gebeyehu, and Karl Leo — Institut fuer Angewandte Photophysik,01069 Dresden,George-Baehr-Strasse 1

We have recently reported organic PIN-type solars with rather high efficiency where P and N are doped wide gap materials and I is a photoactive mixed layer, e.g. zinc phthalocyanine:C60 . Here we present a numerical simulation to solve the differential equation system for multilayer organic solar cells. In the numerical model we take into account effects like bipolar charge carrier drift and diffusion, bulk recombination, generation of free carriers in the mixed layer and charge carriers crossing the energetic barrier at organic-organic interfaces. Parameters such as mobilities, energetic levels of HOMO and LUMO of organic layers and concentration of dopants are derived from independent measurements and literature. Electric field distribution, concentration of free carriers inside the cells and J-V characteristics are described. With the simulation, we can reproduce all major features observed in experimentally obtained J-V curves: The calculated open circuit voltage is close to experimental data and scales with the built-in potential. The shape of the reverse characteristics of illuminated cells is explained by a recombination effect that depends on voltage, light intensity and charge mobility in the mixed layer. Comparison of dark J-V characteristics for PN and PIN structures shows that the current in PIN-cells is limited by space charges in the intrinsic generation layer.