Novel materials for solar cells have been developing very rapidly, for example perovskite based solar cells have recently experienced an unprecedented increase in efficiency to values exceeding 20% within just two years. An important part of the performance of these cells are issues such as stability, cost and manufacturability. In this presentation we demonstrate that the hole transporting layer in such cells can be replaced with polymer-functionalized single-walled carbon nanotubes (SWNTs) embedded in an insulating polymer matrix. With such a composite structure a power conversion efficiency of up to 15.3% is achieved. This layer shows a much improved moisture resistance and at the same time has a thermal stability significantly superior to other hole-transporting materials employed in high-performance perovskite solar cells. This is likely to be a critical development for enhancing the long-term stability of high-efficiency perovskite solar cells.

In addition the same type of SWNT/polymer hole transporting layer can be employed in both conventional organic PhotoVoltaic devices and devices made using colloidal quantum dots, both of which show efficiencies close to 10%.  This type of novel hole transporting layer made from carbon nanotube may well have a very extensive range of applications based on its combination of selective conduction and robust performances