Conductivity Enhancement of PEDOT:PSS Films via Phosphoric Acid Treatment for Flexible All-Plastic Solar Cells

Highly conductive polymer films on plastic substrates are desirable for the application of flexible electronics. Here, we report the conductivity of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) can be enhanced to 1460 S/cm via phosphoric acid (H3PO4) treatment. The conductivity enhancement is associated with the partial removal of PSS from the film. The H3PO4 treatment is compatible with plastic substrates, while sulfuric acid (H2SO4) can easily damage the plastic substrate. With the flexible electrode of poly(ether sulfone) (PES)/H3PO4-treated PEDOT:PSS, we have demonstrated flexible all-plastic solar cells (PES/H3PO4-treated PEDOT:PSS/PEI/P3HT:ICBA/EG-PEDOT:PSS). The cells exhibit an open-circuit voltage of 0.84 V, a fill factor of 0.60, and a power conversion efficiency of 3.3% under 100 mW/cm2 white light illumination.