An essential component in the construction of organic solar cells is the Transparent Conducting Electrode (TCE), which serves to conduct electricity within the solar cell. Graphene has emerged as a promising material for TCEs, because of its high transparency and current-carrying capacity, which surpass that of Indium Tin Oxide (ITO), the most widely used TCE today.
The present technology can be applied towards enhancing the performance of graphene as a TCE, which can thus improve the performance of organic solar cells. As a replacement for the increasingly expensive ITO, it also has the potential to lower the cost of organic solar cells.
A critical factor in optimizing graphene as a TCE is reducing the energy lost between it and the solar cell's electron donor material. With ITO, this issue can be resolved by applying a conducting polymer known as PEDOT:PSS between the TCE and electron donor material. However, fabrication methods thus far have been unable to apply PEDOT:PSS to graphene without impeding its performance.
The current technology proposes a method of applying PEDOT to graphene using oxidative chemical vapor deposition, where an unmodified graphene surface is exposed to a vaporized monomer and an oxidizing agent. This method involves a low temperature, moderate pressure and no use of solvents, meaning that the graphene material and its properties are not compromised in the process. The methodology can be applied to graphene films that have been fabricated either by low pressure chemical vapor deposition (LPCVD) or atmospheric chemical vapor deposition (APVCD).
Does not require any pre-treatment of the graphene surface
- Results in performance comparable to ITO treated with PEDOT:PSS
- Minimizes the performance differences between LPVCD and APVCD graphene
- Lays PEDOT onto graphene in a single step
- Allows PEDOT to be applied in a pattern