Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 67: Organic Semiconductors: Solar Cells II (Joint Session with DS/CPP/O)

HL 67.3: Talk

Friday, March 26, 2010, 10:45–11:00, H16

Analysis of space charge limited currents in P3HT-PCBM based bulk heterojunction solar cells — •Sidhant Bom and Veit Wagner — School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany

The bulk heterojunction organic photovoltaic (OPV) devices have gained attention due to its applicability in large area printing offering a prospect of significant cost reduction. Our work here focuses on modeling of charge carrier transport in P3HT-PCBM based bulk heterojunction OPV devices sandwiched between ITO/PEDOT:PSS and aluminium electrode using glass substrates. For this purpose different blend ratios of P3HT and PCBM were analyzed.

The mobility determined from the space charge limited current is directly correlated to diffusion constant of the charge carriers, which is a crucial parameter in determining the rate of extraction of dissociated charge carriers. Taking into consideration the variation of mobility with charge carrier density at different operating modes of the OPV cell, a charge carrier density dependent mobility was introduced as opposed to constant mobility. This modification not only leads to a more accurate determination of charge carrier mobility but also gives an insight into the morphology of the blend via an energetic disorder parameter. Surprisingly, in comparison to a pure P3HT device, a bulk heterojunction OPV cell showed a significant reduction in this disorder parameter indicating a PCBM induced improvement of the existing P3HT network.