High-performance polymers for flexible OPV raise cell efficiencies
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High-performance polymers for flexible OPV raise cell efficiencies The pitch Thin-film photovoltaics (PVs) offer an affordable alternative to silicon photovoltaics. However, thin-film technologies face many challenges including concerns about toxicity as is the case with cadmium telluride (CdTe)-based PV and difficulties in scale-up as evidenced by copper indium gallium diselinide based PV. Organic photovoltaic (OPV) cells printed on flexible substrates are free of toxic materials and cost competitive since they can be manufactured by rollto-roll processes. In addition, OPVs have improved performance in low light, can be transparent and colorful, and are more flexible and lower in weight than current PV. OPV technology has grown during the past decade with cell efficiencies quadrupling. To date, the highest NREL-certified number for OPV cells is 8.6% as reported by the University of California–Los Angeles. Solarmer Energy, a developer of OPV, has been at the forefront of this technology and has demonstrated four world record efficiencies in the last two years. With the recent growth of mobile devices, tablets, and e-readers, the prospect of having conveniently accessible portable power has rapidly progressed into a much sought-after commodity. Because of its light weight and flexibility, OPV can be integrated into portable electronic devices with minimal increase in weight. OPV opens new markets for products that were not possible for traditional PV. For example, in the outdoor products market, gear for hiking and camping can be redesigned to incorporate electrical power generation.
The technology In an OPV cell, various functional layers are deposited in a stacked structure, which upon light absorption produces electrical power. The heart of this stack is the active layer comprised of donor
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and acceptor materials with energy levels that must be properly matched in order to maximize the power conversion efficiency (PCE). Low-bandgap polymers with absorption extending into the infrared region are optimal for increasing PCE. In addition, the energy levels are tuned to increase the open-circuit voltage (VOC) without sacrificing the current density and fill factor Solarmer’s roll-to-roll pilot production line for the manufacture of organic photovoltaic modules. (ratio of actual maximum obtainable power to theoretical power). Solarmer currently has a portfolio of more than 50 line to develop roll-to-roll processes for polymers with efficiencies ranging from producing OPV has been built (shown 6% to more than 8.5% in a wide range of in the figure). The process shares many voltages, colors, and transparencies. similarities with traditional printing Many research groups are targeting and coating. However, low viscosity of the design and synthesis of ideal doinks, low film thicknesses, precise edge nors with optimal characteristics. This alignment of all the functional layers, involv
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