Large-scale full-solution, vacuum-free gravure printed ITO-free flexible organic solar cells

Bachelor Thesis from the year 2014 in the subject Technology, grade: 1,0, Friedrich-Alexander University Erlangen-Nuremberg, course: Nanotechnologie, language: English, abstract: This bachelor thesis presents the fabrication and evaluation of large-scale full-solution roll-to-roll processed, ITO-free flexible organic solar cells in a modified inverted device geometry by gravure printing on a discrete laboratory-scale printing system. The layer stack is based on flexible PET substrate whereupon the back silver cathode was printed on top. The electron transport layer of ZnO and a double light absorbing photoactive layer of P3HT:PCBM, the hole transport layer of PEDOT:PSS and front silver anode were printed consecutively. All layers were roll-to-roll gravure printed from solution under full ambient vacuum-free conditions at a web speed of 2 m min?1. The completed solar cells were characterized by J-V and comprising layers by light beam induced current measurements. For fast testing and reproducibility experiments the remaining layers of the stack after each gravure printed film were deposited by slot-die coating and flexographic printing on a single roll coating system. Unfortunately functional organic solar cells of a fully gravure printed layer stack could not be found. A power conversion efficiency of 0.15 % of partly roll-to-roll gravure printed and residuary roll-based slot-die coated and flexographic printed organic solar cells under AM1.5G illumination was obtained. The thesis contains a brief introduction in the topic of renewable energies and organic photovoltaic followed by the state of art in two-dimensional gravure printing organic solar cells and the motivation to particularly foreground this fabrication method. In the fundamentals part the working principle, device geometries, affiliated by the concept of ITO-free organic solar cells and materials in an organic photovoltaic device including characterization methods are presented. Afterwards large-scale manufacturing techniques of organic photovoltaic comprising coating and printing technologies are reviewed and the roll-to-roll manufacturing strategies are introduced. In the experimental part the design, machinery and equipment used and fabrication of gravure printed flexible organic solar cell are chronologically described in detail in connection with presenting and discussing the results after characterizing the completed solar cells. Challenges that were faced during the studies are described subsequently and solutions of appeared problems are presented. A conclusion and outlook finalizes the thesis.