Enhanced Charge-Carrier Transport through Shorter Carbon Nanotubes in Organic Photovoltaics

Abstract

We demonstrate for the first time the efficiency improvement of organic photovoltaics by the addition of shorter multiwalled carbon nanotubes (MWNTs) generated by size sorting. The different size MWNTs were generated by size sorting a batch of carboxylated MWNTs and were introduced as charge carriers in poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction photovoltaic cells. As compared to a control with only PCBM, the addition of the long and short MWNT resulted in 12 and 34% improvement in short circuit current density (J sc) respectively. The results indicate that length of carbon nanotubes is an important consideration in photovoltaic and possibly other nanoelectronic devices.

Fractionation of carboxylated carbon nanotubes and the corresponding variation in their colloidal behavior

“…More recently there has been much interest in the effect of size on the physical and chemical properties of CNTs. 3,4 For example some applications in electronic, biological, and optical devices benet from shorter nanotubes (less than 500 nm), while others like eld emission displays require relatively longer tubes (500-2000 nm) due to their more uniform emission. 5 As CNTs nd many real world applications, they will be released more and more into the environment.…”