Highly conductive PEDOT/silicate hybrid anode for ITO-free polymer solar cells

In this work, we prepared ITO-free photovoltaic devices (PVDs) using a transparent poly(3,4-ethylenedioxythiophene):silicate (PEDOT:SiOx) composite anode equipped with low surface resistance and high transparency. A mixture of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C60 butyric acid methyl ester (PCBM) was used as a photoactive layer. PEDOT:SiOx film was fabricated with an inorganic silicate network via the oxidative polymerization of EDOT and in-situ sol–gel process of TEOS, which should allow enhanced adhesion and bonding strength between the conducting polymers and the glass substrates to be obtained without any significant deterioration of the desired electronic properties of the conducting polymers. The transmittance and surface resistance of the PEDOT:SiOx film were varied in the ranges of 55–94% at 510 nm and 80–380 Ω/sq, respectively. The power conversion efficiency of the ITO-free PVD with PEDOT:SiOx anode was ca 1.2% under an illumination of AM 1.5 G (100 mW/cm2).