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

Abstract

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, J_sc, of 0.44 mA cm^-2, open circuit voltage, V_oc, 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.

Indexing terms:

• Organic solar cells
• PCBM
• P3HT
• Bulk hetero junction
• MEHPPV
• CNPPV

Additional information

Notes on contributors

S Sundar Kumar Iyer

S. Sundar Kumar Iyer is an assistant professor at Indian Institute of Technology (IIT) Kanpur. He received his BTech and MS degrees from IIT Madras and PhD from the University of California at Berkeley. His PhD thesis was based on fabrication of silicon on insulator wafers using high throughput plasma immersion ion implantation. He then worked with the embedded DRAM group at IBM, Hopewell Junction, New York and was involved in developing and qualifying the polysilicon based electrically programmable fuse. At IIT Kanpur, he has been a part of the Samtel Centre for Display Technologies and has been focusing on the research of organic solar cells with an aim to understand the devices and improve their efficiencies.

Dipesh Bajaj

Dipesh Bajaj obtained his B.E. degree in Electronics and Instrumentation Engineering from SGSITS, Indore (under RGPV, Bhopal, Madhya Pradesh). Dipesh Bajaj completed his MTech degree at IIT Kanpur in May 2006. His MTech thesis work was on “A study of P3HT/PCBM bulk hetero junction organic solar cells”. Currently he is working as a Design Engineer in the implementation team at AMD India Engineering Centre Pvt Ltd.

Amruta Bhat

Amruta Bhat obtained her BE degree in Electronics and Instrumentation Engineering from SGSITS, Indore (under RGPV, Bhopal, Madhya Pradesh). She got her MTech degree at IIT Kanpur in May 2006. Her MTech thesis work was on “Comparative study of organic solar cells based on MEHPPV/CNPPV and MEHPPV/PCBM”. Currently she is working with the flows and methodology group at Freesale Semiconductors at Noida, UP.