Organic Heterojunction Photovoltaic Cells Made of Discotic, Mesogenic Materials

We made photovoltaic cells containing two organic layers. The hole-conducting layer consists of a hexa-peri-hexabenzocoronene (HBC) derivative. The electron-conducting component is an alkylester of perylene tetracarboxylic acid. Both compounds form columnar mesophases which can provide 1D pathways for transport. The current/voltage-characteristics of the two-layer devices indicate a photovoltaic effect with an open circuit voltage of Voc ≈ 0.8 V, a short circuit current of Isc ≈ 3.9 μA/cm2, and a filling factor of FF ≤ 31%. The spectral distribution of the photocurrent of different samples indicates that excitations of the perylene derivative or of the HBC derivative both can lead to a photovoltaic effect.