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 ID pathways for transport. The current/voltage-characteristics of the two-layer devices indicate a photovoltaic effect with an open circuit voltage of V-oc approximate to 0.8 V, a short circuit current of I-sc approximate to 3.9 muA/cm(2), and a filling factor of FF less than or equal to 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.