High open circuit voltage organic photovoltaic cells based on oligothiophene derivatives

For the purpose of developing organic photovoltaic devices with good performance characteristics, The authors have fabricated two cells using 5-vinyl-2,2('):5('),2('):5('),2(')-quarterthiophene (V4T), 5-vinyl-2('):5('),2('):5('),2('):5('),2('')-quinquethiophene (V5T) and 3,4,9,10-perylenetertracarboxylic dianhydride (PTCDA). The indium tin oxide (ITO)/V4T/PTCDA/Al cell has an open circuit voltage (V-oc) of 2.07 V and a photoelectric conversion efficiency of 2.32%. The ITO/V5T/PTCDA/Al cell has an V-oc of 1.87 V and a photoelectric conversion efficiency of 2.67%. The two cells have higher V-oc (1.87-2.07 V). It is possible that intermolecular hydrogen bonding between -CH = CH2 group of VnT with carboxylic dianhydride of PTCDA contributes to the enhancement by promoting forward interfacial electron transfer and eliminating the subconducting band trap sites. (c) 2006 American Institute of Physics.