Charge-transfer nanocomposites (CTNs) are blends or composites of quantum-functional nanophase materials; such as carbon nanotubes, quantum dots, and fullerenes with electro active conjugated polymers. These materials exhibit distinctive properties over polymer-polymer blends, in particular enhanced electro activity, photoemission, and photo absorption.
CTNs in their various guises have been extensively used for highly efficient organic light-emitting diodes, highly conductive thin films, and, more recently, efficient organic photovoltaics, but advances have been limited because technology suffers from extreme sensitivity to the environment, including oxidation, delamination of contacts due to water and limited by carrier mobility and optical coupling.

But today's polymer photovoltaic devices are closing the gap between potential performance and actual efficiency and have achieved record photovoltaic conversion efficiencies of nearly double the previously reported values. This is due the ordered placement of nanostuctures into architectures that extend over many microns called mesoscale ordering. This placement of nanomaterials into three-dimensional arrays referred to as ‘scaled structures’ or ‘hierarchical structures’ have provided a powerful new tool for developing high-performance photovoltaics.

These more efficient devices are possible with a disordered array of solubilized fullerenes dispersed in a P3HT thin film device. Such materials when annealed to a temperature approaching the glass transition of the polymer the polymer crystallizes, and hole mobilities within the polymer phase increase dramatically forming high-aspect- ratio nanocrystalline grains of PCBM (nanowhiskers) in the matrix giving conversion efficiency nearly 45% of the theoretical maximum for this host material.