Flexible organic photovoltaic devices based on oligothiophene derivatives

For the purpose of developing flexible organic photovoltaic devices,we have fabricated two flexible devices using 5-formyl-2,2':5',2":5",2"'-quaterthiophene (4T-CHO),5-formyl-2,2':5',2":5",2'":5"',2"'-quinquethiophene (5T-CHO)and 3,4,9,10-peryle-netertracarboxylic dianhydride(PTCDA).The PET-ITO/4T-CHO/PTCDA/AI device has an open circuit voltage (V∝)of 1.56 V,photoelectric conversion efficiency of 0.77%.The PET-ITO/ST-CHO/PTCDA/AI device has a V∝ of 1.70 V,photoelectric conversion efficiency of 0.84%.The two flexible devices have high V∝(1.56 and 1.70 V).It is possible that intermolecular hydrogen bonding between-CHO group of nT-CHO and carboxylic dianhydride of PTCDA contributes to enhancing the efficiency by promoting interfacial electron transfer and eliminating the subconducting band trap sites.