Project TitleElectron-Blocking Layer for Improved Organic Photovoltaics
Track Code2006-151
Short Description

An electron-blocking / hole transport layer for organic photovoltaics.


Northwestern researchers have developed a new technology to improve the power conversion efficiency of current bulk heterojunction (BHJ) solar cells. Organic photovoltaics (OPV) offer several advantages over traditional inorganic photovoltaic cells, including fabrication with flexible substrates, lightweight, and production by inexpensive techniques such as spin-coating and printing. However, BHJ solar cells exhibit low conversion efficiencies, insufficient for commercial use. This new technology focuses on improving one key parameter in solar cell performance namely, the open-circuit voltage (Voc), which is believed to originate from the difference in energy between the highest occupied molecular orbital of the donor and the lowest unoccupied molecular orbital of the acceptor. This invention provides an electron-blocking layer (EBL) between the active layer blend MDMO-PPV:PCBM and P3HT:PCBM (donor polymer: acceptor material) and the ITO anode. The EBL serves to prevent electrons in the PCBM from traveling to the ITO, thus forcing the electrons to flow in the correct direction for collection at the cathode. With the EBL, the overall power conversion efficiency of solar cells exhibits greater Voc.

TagsENERGY: solar, MATERIALS: photovoltaic
Posted DateMay 3, 2011 4:11 PM


Alexander Hains
Michael Irwin
Tobin Marks*
He Yan


Solar Cell


Increased organic photovoltaics efficiency

IP Status

Issued US Patent Nos. 7,799,990 and 8,399,761 

Contact Information

Zach Brown, PhD
Invention Associate
(p) 847-491-4629