Time-dependent efficiency measurements of polymer solar cells with dye additives: unexpected initial increase of efficiency
Department of Chemistry and Biochemistry, Santa Clara University,
CA 95053, USA
2 Department of Physics, Santa Clara University, Santa Clara, CA 95053, USA
3 Center for Nanostructures, Santa Clara University, Santa Clara, CA 95053, USA
* e-mail: email@example.com
Received in final form: 20 January 2018
Accepted: 24 January 2018
Published online: 9 April 2018
We report the effects of the addition of two azo-dye additives on the time-dependent efficiency of polymer solar cells. Although the maximum efficiencies of devices containing different amounts of dye do not vary greatly over the selected concentration range, the time dependence results reveal a surprising initial increase in efficiency in some samples. We observe this effect to be correlated with a leakage current, although a specific mechanism is not yet identified. We also present the measured lifetimes of these solar cells, and find that variations in dye concentrations produce a small effect at most. Characterization of the bulk heterojunction layer (active layer) morphology using atomic-force microscope (AFM) imaging reveals reordering patterns which suggest that the primary effects of the dyes arise via structural, not absorptive, characteristics.
Key words: polymer photovoltaic / dye additives / morphology / leakage current
© K.J. Bandaccari et al., published by EDP Sciences, 2018
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