Charge transfer mechanisms of P3HT: PCBM photovoltaic cells containing a tungsten oxide hole transport layer

Organic photovoltaic (OPV) cells containing a tungsten oxide (WO
₃
) layer inserted between the indium-tin-oxide and the poly(3-hexylthiophene) and the derivative [6,6]-phenyl-C
₆₁
-butyric acid methyl ester active layer were fabricated. The short circuit current density, the open circuit voltage, the fill factor, and power conversion efficiency of the OPV cells under an AM 1.5G were 7.45 mA/cm
²
, 0.63 V, 0.59, and 2.8%, respectively. The charge transfer mechanisms of the OPV cells containing a WO
₃
layer are described on the basis of the experimental results and energy band diagrams.