Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid (PEDOT:PSS) has been widely used as hole collector in
organic solar cells. We report a study of the PEDOT:PSS quality grade on the current voltage characteristics of a planar
heterojunction type photovoltaic cells made of discotic molecules. Electroabsorption (EA) studies were performed on
these components in order to understand the correlation between electrode materials and Voc. From the experimental
results it can be shown a high open circuit voltage of 1.5 V<sub>oc</sub>.
High exciton diffusion lengths and charge carrier mobilities along the columns and the capability to align make columnar LCs promising materials for solar cells. Given the lack of columnar LCs based on acceptor-type aromatic systems needed for donor-acceptor heterojunction devices, we have developed novel carboxylic-functionalized arene chromophores. We found large columnar temperature ranges and widely tunable electronic properties. First device results are very encouraging, including very high open circuit voltages. This illustrates that the combination of both donor-type and acceptor-type columnar LCs can lead to solar cells with pronounced donor-acceptor junctions. The perspective of using the good transport properties of such columnar materials throughout the active layers offers thus a novel approach to highly structured plastic photovoltaic devices.