Optical coherence tomography (OCT) as a 3-dimensional imaging technique for non-destructive testing of roll-to-roll coated polymer solar cells

We have recently demonstrated the first application of optical coherence tomography (OCT) as a 3-dimensional (3D) imaging technique to visualize the internal structure of complete multilayered polymer solar cell modules (Thrane et al., Solar Energy Materials & Solar Cells 97, 181-185 (2012)). The 3D imaging of complete polymer solar cells prepared by roll-to-roll coating was carried out using a high-resolution 1322nm OCT system having a 4.5 microns axial resolution and a 12 microns lateral resolution. It was possible to image the 3-dimensional structure of the entire solar cell that comprise UV-barrier, barrier material, adhesive, substrate and active solar cell multilayer structure. In addition, it was found that the OCT technique could be readily employed to identify coating defects in the functional layers, making it a potential technique to enable process control by real-time adjustment to the production process.