Comparison of Fast Roll-to-Roll Flexographic, Inkjet, Flatbed, and Rotary Screen Printing of Metal Back Electrodes for Polymer Solar Cells

The majority of polymer solar cells reported today employs processing under high vacuum for one or more of the layers in the solar cell stack. Most notably the highly conducting metal back electrode is almost exclusively applied by evaporation of the pure metal. While it is not impossible to envisage mass production of polymer solar cells using vacuum processing it does present some drawbacks in terms of both processing speed, capital investment in processing equipment technical yield and direct process energy. One crucial step is the economical fabrication of the silver back electrode responsible for current collecting and the serial connection of the solar cells to modules. Most of all small-scale record cells are fabricated with evaporated back electrodes, which are costly and challenging to transfer to a fast R2R process.