Enhanced storage/operation stability of small molecule organic photovoltaics using graphene oxide interfacial layer |
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Authors: | Qing-Dan Yang Tsz-Wai Ng Ming-Fai Lo Ning-Bew Wong Chun-Sing Lee |
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Affiliation: | 1. Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong Special Administrative Region;2. Department of Physics & Materials Science, City University of Hong Kong, Hong Kong Special Administrative Region;3. Department of Biology & Chemistry, City University of Hong Kong, Hong Kong Special Administrative Region |
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Abstract: | Graphene and graphene oxide (GO) have been applied in flexible organic electronic devices with enhanced efficiency of polymeric photovoltaic (OPV) devices. In this work, we demonstrate that storage/operation stability of OPV can be substantially enhanced by spin-coating a GO buffer layer on ITO without any further treatment. With a 2 nm GO buffer layer, the power conversion efficiency (PCE) of a standard copper phthalocyanine (CuPc)/fullerene (C60) based OPV device shows about 30% enhancement from 1.5% to 1.9%. More importantly, while the PCE of the standard device drop to 1/1000 of its original value after 60-days of operation-storage cycles; those of GO-buffered device maintained 84% of initial PCE even after 132-days. Atomic force microscopy studies show that CuPc forms larger crystallites on the GO-buffered ITO substrate leading to better optical absorption and thus photon utilization. Stability enhancement is attributed to the diffusion barrier of the GO layer which slow down diffusion of oxygen species from ITO to the active layers. |
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Keywords: | Graphene oxide Small molecules Organic photovoltaics Stability Buffer layer |
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