Improving Performance of Organic Solar Cells Using Ytterbium as Buffer Layer on Cathodes

초록

The interfacial buffer layer improves power conversion efficiency (PCE) in organic photovoltaic cells (OPVs) as it helps to form ohmic contact between the active layer and the cathode metal. Here, we introduce ytterbium (Yb) as a cathode buffer layer in conventional poly(3-hexylthiophene):[ 6,6]-phenyl C-61 butyric acid methyl ester (P3HT:PCBM-60) bulk hetero junction (BHJ) cells. This buffer layer acts as an electron-extraction layer, which increases the open circuit voltage (V-oc), leading to higher efficiency and more stable organic electronic devices. The power conversion efficiency (PCE) of the organic photovoltaic cells (OPVs), composed of ITO/PEDOT:PSS/P3HT:PCBM/Yb/Al, reaches up to 3.12%, recording 63% of the fill factor (FF) in one-Sun irradiation, and over 50% of its original PCE is retained after 72 hours. It was found that Yb-based cells have a significant shunt resistance, which contributes to a high FF and V-oc. It has been demonstrated that the properties of the cathode buffer layer can have a substantial impact on the efficiency and stability of OPVs.

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