H. Lee, K.T. Ampofo, D.S. Kim
Keywords: OPV, solution shearing, meniscus coating, printed electronics
Summary:Organic photovoltaic cells (OPV) are gaining high prominence and renown because of their low manufacturing cost, flexibility, Roll to roll (R2R) compatibility and their ability to produce clean energy. In recent years, considerable effort has been made towards realizing a fully commercialized organic photovoltaic cell. The main goal of research is to realize low cost, large area solar cells with high throughput Roll to roll (R2R) printing and coating techniques. However, Device flexibility and cost is limited by the use of Indium Tin oxide. Indium Tin Oxide (ITO), which is mainly used as the transparent electrode for organic photovoltaic cells is expensive and the price is expected to increase further due to the dwindling resources of indium in the world. ITO is also brittle and therefore cannot be used as material for flexible devices and roll to roll (R2R) manufacturing systems. A lot of research is therefore being conducted to solve this problem. An all solution shearing approach was adopted in this research In this research we demonstrated a meniscus guided solution process coating technique (solution shearing) for the fabrication of organic photovoltaic cells. ITO free transparent electrode consisting of a silver (Ag) grid (mesh) in conjunction with a PEDOT: PSS layer on polyethylene terephthalate (PET) substrate was fabricated. The Ag grid was fabricated by thermal imprinting of PET and doctor blading of patterns with Ag paste. The PEDOT: PSS layer was fabricated using solution shearing technique. The electron transport layer (ZnO) and the photoactive layer (P3HT:PCBM) were also deposited by solution shearing, which has been demonstrated to improve the mobility of thin film materials by the application lattice strain. The Hole transport layer (PEDOT :PSS) and top electrode (Ag) were deposited by screen printing . Solution shearing technique produced highly crystalline thin films and an overall device fill factor of about 60%.