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We have investigated the influence of the poly(3,4-ethylenedioxythiophene)-blend-poly(styrene-sulfonate) (PEDOT:PSS) layer on the short-circuit current density ([J.sub.sc]) of single planar heterojunction organic solar cells based on a copper phthalocyanine (CuPc)-buckminsterfullerene ([C.sub.60]) active layer. Complete optical and electrical modeling of the cell has been performed taking into account optical interferences and exciton diffusion. Comparison of experimental and simulated external quantum efficiency has allowed us to estimate the exciton diffusion length to be 37 nm for the CuPc and 19 nm for the [C.sub.60]. The dependence of short-circuit current densities versus the thickness of the PEDOT:PSS layer is analyzed and compared with experimental data. It is found that the variation in short-circuit current densities could be explained by optical interferences. OCIS codes: 040.5350, 160.4890.

Molecular blends of pentacene: N, N′-ditridecylperylene-3, 4, 9, 10-tetracarboxylic diimide (PTCDI-C13H27) permit to cover the visible part of the solar spectrum with an absorption onset at 730 nm. Although charge mobilities of pentacene and PTCDI are rather large, the efficiency of pentacene:PTCDI-C13H27 blended devices is still lower than that of poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester devices. Comparisons between experimental results and optical modeling indicate that more than 30% of the photocurrent is lost in the blend while the short circuit current should reach 13 mA cm-2 in the absence of recombination processes. [ABSTRACT FROM AUTHOR]

The optimization of pentacene: N, N'-ditridecylperylene-3, 4, 9, 10-tetracarboxylic diimide (PTCDI-[C.sub.13][H.sub.27]) blends is examined through optical modeling. Results conclude that the cells made with pentacene:PTCDI blends have the ability to reach as high as 13 mA [cm.sub.-2] short circuit currents.

Results obtained by using a software for automatic optimization of the electromagnetic field in organic solar cells are presented. This numerical tool may be useful for any organic device having a multilayer thin-film structure. Interference effects are taken into account inside the whole structure. The software allows calculation of the distribution of the electromagnetic field with respect to the depth. It gives routines for one-run determination of the optimal thicknesses of each layer with the view to maximize and balance the square modulus of the normalized electromagnetic field in photoactive areas. The method principles are presented and some examples are given. A global optimization, under incident solar illumination in the wavelength range 300-800 nm is demonstrated for organic solar cells composed of the DiO-PFDTBT/C60 bilayer junction. It is also shown that this numerical method can also be applied to find the optimal design of photovoltaic devices such as multi-junction cell or tandem cell. [ABSTRACT FROM AUTHOR]