Effective mobility and photocurrent in carbon nanotube–polymer composite photovoltaic cells

Abstract

We examine the dark and the illuminated current–voltage (J–V) characteristics of poly(3-octylthiophene) (P3OT)/single-wall carbon nanotube (SWNT) composite photovoltaic cells as a function of SWNT concentration. Using an exponential band tail model, the influence of SWNT concentration on the J–V characteristics of the cells is analysed in terms of corresponding parameters such as effective hole mobility, short-circuit current, and open-circuit voltage. For the device with optimum 1% SWNT concentration, the increased photoresponse (∼500 times) as compared to the pristine P3OT cell can be attributed partly to the increase (∼50 times) in effective hole mobility, due to the reduction of localized states of the pristine P3OT matrix, and partly to the enhanced exciton extraction at the polymer/nanotube junctions.

Nano‐Engineering of SWNT Networks for Enhanced Charge Transport at Ultralow Nanotube Loading

“…[ 16 ] Ineffi cient mixing and formation of SWNT aggregates moreover increases the amount of nanotubes needed to form continuous pathways between two interfaces, which unnecessarily increases materials cost and lowers performance. [17][18][19] Network formation and percolation at reduced loading has been long studied and would be advantageous for many applications, yet methods to controllably form percolated networks at low tube concentrations are still lacking. [ 20 ] In order to increase a composite's electrical performance and reduce materials costs, such methods must be developed.…”

Carbon nanomaterials in organic photovoltaic cells

“…Because a metallic material acts as a recombination center [17], the incorporation of a metallic material in the active layer of an OPV device is inappropriate. In contrast to the semiconducting behavior of fullerene, the electrical properties of CNTs and graphenes are metallic.…”

“…In contrast, MWCNTs have a metallic property. Metallic CNTs decrease the performance of an OPV cell because they act as recombination and trap centers [17]; hence, separation of the metallic SWCNTs and semiconducting SWCNTs is necessary beforehand. Ultracentrifugation with DNA wrapping [73] and a thermal treatment [74] have been suggested for this separation.…”

Enhanced polymer light-emitting diode property using fluorescent conducting polymer-reduced graphene oxide nanocomposite as active emissive layer

“…Very little attention has, however, been paid toward LED application of these materials, although the presence of conducting character of graphene/graphene-based materials significantly suppresses the effective hole mobility and favors the formation of recombination pathways (Kymakis et al 2007). Few recent reports indicate tremendous possibility of using soluble graphene oxides as transparent electrodes Han et al 2012) and the hole transport layer (HTL) Zhong et al 2011) in LED applications.…”