The influence of substrate heating on morphology and layer growth in C60 : ZnPc bulk heterojunction solar cells

Journal article

The change of morphology in mixed layers due to different substrate temperature T of organic solar cells containing C₆₀ and zinc phthalocyanine (ZnPc) is studied. Heating the substrate during deposition of the bulk heterojunction C₆₀:ZnPc leads to a significant improvement of solar cell performance, mainly due to an increase in photocurrent and fill factor (FF). This is attributed to improved charge carrier percolation pathways within the C₆₀:ZnPc blend. Using atomic force microscopy, scanning electron microscopy, transmission electron microscopy, organic field effect transistor, X-ray diffraction, and absorption measurements, we observe aggregation, cluster-like, and polycrystalline growth of the heated bulk layer. This provides better transport percolation paths by inducing a phase separation of the molecules. Heated blend layer with thickness of 60 nm shows high performance without loss in FF. When heating the substrate to the optimum temperature of 110 °C, a power conversion efficiency of 3.0% is achieved, compared to 1.4% for an identical device prepared on a substrate held at room temperature. © 2010 Elsevier B.V. All rights reserved.

Authors: Pfuetzner, S; Jankowski, J; Hein, M; Meiss, J; Schuenemann, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Organic Electronics: physics, materials, applications
• Volume: 12
• Issue: 3
• Pages: 435-441
• Publication date: 2011-03-01
• DOI: 10.1016/j.orgel.2010.12.007
• ISSN: 1566-1199
• Language: English
• Keywords: Organic; Small molecules; Morphology; Solar cell; C60; ZnPc