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Photovoltaic Behaviour of Organic Polymer—PCBM Bulk Hetero Junctions Solar Cells

Organic polymer based solar cells hold lot of promise for low-cost large volume solar cell production. This paper explains the operation of organic solar cells and its evolution to the bulk hetero-junction structures. Solar cells fabricated with a blend of poly (2-methoxy), 5-(2-ethylhexoxy)-1, 4- phenylenevinylene (MEHPPV) and cyano-substituted poly (2,5-dialkoxy-p-phenylene vinylene (CNPPV) are compared with those fabricated with a blend of MEHPPV and higher electron mobility (6,6)-phenyl C 61 butyric acid methyl ester (PCBM). The improvement in device performance by replacing MEHPPV in the blend with poly 3-hexyltbiophene (P3HT), is then demonstrated. The P3HT:PCBM blend bulk hetero- junction device has a short circuit current density, Jsc, of 0.44 mA cm-2, open circuit voltage, Voc, of 0.41 V and a fill factor, FF, of 0.28. This device is then characterised under different intensities of light irradiation which indicates that the recombination of electrons and holes are high in these devices which needs to be reduced by improved processing to achieve higher efficiency solar cells.