Electroabsorption studies of organic bulk-heterojunction solar cells

Journal article

The working principle of organic bulk-heterojunction solar cells is a widely discussed topic. For thin film solar cells it is commonly supposed that the built-in potential V_bi is the driving force for charge separation and determines the open-circuit voltage V_oc. In former works, V_bi was estimated by measuring V_oc in the saturation regime. To check the validity of this model, the direct measurement of the built-in potential is desirable. We have investigated the origin of the open-circuit voltage of organic bulk-heterojunction solar cells by means of electroabsorption spectroscopy. This technique allows measurement of the built-in potential directly and therefore permits an independent measurement of V_bi and V_oc. In our experiments on indium tin oxide/poly(3,4-ethylendioxythiophene) : poly(styrene-sulfonate)/poly(2 -methoxy-5-(3′,7′-dimethyloktyloxy)-p-phenylene-vinylene) : 1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6)C₆₁/metal bulk-heterojunction solar cells no significant correlation between the open-circuit voltage and the built-in potential was observed. For certain electrode materials, i.e. gold and copper, V_oc exceeded V_bi which is revealing of semipermeable membranes. © 2005 Elsevier B.V. All rights reserved.

Authors: Zimmermann, B; Glatthaar, M; Niggemann, M; Riede, M; Hinsch, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Thin Solid Films
• Volume: 493
• Issue: 1-2
• Pages: 170-174
• Publication date: 2005-12-22
• DOI: 10.1016/j.tsf.2005.04.089
• ISSN: 0040-6090
• Language: English
• Keywords: Electroabsorption; Open-circuit voltage; Built-in potential; Organic solar cell; Semipermeable membranes