text: Sample preparation of the OPV is of the utmost importance when performing pc-AFM studies. The sampling substrate is recommended to be conductive, as well as transparent, to the light source which is irradiated upon it. Numerous studies have used ITO-coated glass as their conductive substrate. Because of high cost of ITO, however, there have been attempts to utilize other semiconducting layers, such as zinc oxide (ZnO) and carbon nanotubes as an alternative to ITO. Although these semiconductors are relatively inexpensive, high quality ITO layers are still being used extensively for PV applications. Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), more commonly known as PEDOT:PSS, is a transparent, polymeric conductive layer which is usually placed between the ITO and the active OPV layer. The PEDOT:PSS is a conductive polymer is stable over various applied charges. In most studies, PEDOT:PSS is spin-coated onto the ITO-coated glass substrates directly after plasma cleaning of the ITO. Plasma cleaning, as well as halo-acid etching, have been shown to improve the surface uniformity and conductivity of the substrate. This PEDOT:PSS layer is then annealed to the ITO prior to spin-coating the OPV layer onto the substrate. Studies by Pingree et al. have shown the direct correlation between annealing time and both peak and average photocurrent generation. Once this OPV film is spin-coated onto the substrate, it is then annealed at temperatures between 70 and 170 °C, for periods up to an hour depending on the procedure as well as OPV being used.