Zawacka, Natalia Klaudia1; Andersen, Thomas Rieks4; Andreasen, Jens Wenzel1; Rossander, Lea Hildebrandt1; Dam, Henrik Friis5; Jørgensen, Mikkel1; Krebs, Frederik C1
1 Department of Energy Conversion and Storage, Technical University of Denmark2 Functional organic materials, Department of Energy Conversion and Storage, Technical University of Denmark3 Imaging and Structural Analysis, Department of Energy Conversion and Storage, Technical University of Denmark4 Risø National Laboratory for Sustainable Energy, Technical University of Denmark5 Department of Micro- and Nanotechnology, Technical University of Denmark
The effect of twelve different additives on organic solar cells with an active layer based on poly-3- hexylthiophene (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) has been studied in this work and tested for suitability in roll-to-roll slot-die coating. Three of the twelve additives increased the solar cell efficiency while the rest showed no effect or a negative influence on the efficiency and coatability. In cases where the additive caused an increase in performance the relation to surface topography and the structure was investigated using Atomic Force Microscopy (AFM), UV-Vis Spectroscopy and Small Angle X-ray Scattering (SAXS) for cells prepared with 1-chloronaphthalene (CN), N-methyl-2-pyrrolidone (NMP) and 1,3-dimethyl-barbituric acid (BARB) as processing additives. The studies suggested that the use of these additives resulted in films with improved morphology and electrical properties of the active layer. The effect of the CN on structural evolution during different solvent evaporation and annealing times was further investigated with an in situ roll-to-roll X-ray study. Lifetime studies under continuous illumination were used to assess the impact of the additives on the stability of the prepared devices that had an active area of 1 cm2.