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We show that it is possible to perform ellipsometry on large area roll-to-roll (R2R) coated solar cells on flexible substrates and further demonstrate that the slot-die coating technique employed yields the same bulk heterojunction (BHJ) film morphology and vertical phase separation as laboratory samples prepared by the spin coating technique. The solar cell device geometry was Kapton/Al/Cr/P3HT:PCBM/PEDOT:PSS/Ag. Variable angle ellipsometry was used to determine the optical dispersions of the pure phases of P3HT and PCBM allowing an effective medium approximation model to be employed. It was found that a top layer phase separation of P3HT and a vertical linear gradient of P3HT and PCBM best described the BHJ layer. The model was tested for samples of varying thickness and blend composition, model parameters including thickness (AFM), vertical composition (XPS depth profiling), and optical transmission (optical simulation and UV–visible spectroscopy comparisons) was confirmed to comply with the model. A means of quality testing and optimization of the coating procedure line scans across a R2R slot-die-coated sample over large distances (8 cm) was made giving insight into thickness and composition uniformity.
|Journal||Journal of Physical Chemistry Part C: Nanomaterials and Interfaces|
|Publication status||Published - 2011|
Bibliographical noteThis work was supported by the Photovoltaic European
Research Area Network (PV-ERA-NET), under the project
acronym POLYSTAR and by the European Commission
through the Seventh Framework Programme for Research and
Technological Development under the Information and Communication
Technologies (ICT) project acronym HIFLEX
(Grant Number 248678).
- Polymer solar cells