“Polymer Solar Modules: Laser Structuring and Quality Control by Lock-In Thermography”

Abstract

Abstract:Polymer solar modules, based on glass or flexible PET-substrates, structured either by laser ablation, mechanical scribing, or by a combination of the two, were prepared and analyzed. The photo-active layer of the solar modules is based on poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester or Poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:phenyl-C71-butyric acid methyl ester donor-acceptor bulk heterojunctions. Since such polymer-fullerene solar cells and modules are designed in a multilayer architecture, local defects such as shunts or blocking junctions in the device can cause critical losses to the solar module performance. Of special importance for solar module preparation is the structuring process, as it allows the serial interconnection of the cells. The high precision required for removing neither too few nor too much of the thin layers to be structured presents challenges in the processing of polymer solar modules. Herein we demonstrate that laser structuring is a suitable technology to face these challenges. We report about completely or partially laser structured polymer photovoltaic modules. By using highly sensitive dark lock-in thermography we analyze the influence of defects and failures on the performance and operation of solar module devices. Finally, promising results for fully laser structured solar modules on glass and partly laser structured solar modules on PET are presented.