Organic solar cells using few-walled carbon nanotubes electrode controlled by the balance between sheet resistance and the transparency

Organic photovoltaic devices (OPD) using high conductive transparent few-walled carbon nanotubes (FWNT) film prepared by spraying was fabricated as a selective hole collection. Photovoltaic response with different sheet resistance (Rs) and the transparency (T) of FWNT film was investigated. Maximum efficiency of OPD up to 0.61% with the structure of FWNT (T=70%, Rs =86 /)/poly(3-hexylthiophene): [6-6]phenyl- C61 -butyric acid methyl ester/Al demonstrates a promising alternative of ITO (0.68%) with almost identical operation. The performance improvement results from the optimal balance between sheet resistance and transparency with three-dimensional network interface between nanotubes and polymers.