Mapping photocurrent generation in the nanoscale
Mapping photocurrent generation in the nanoscale: a probe to the 3D morphology of organic solar cells
Currently, only 0.3% of the European electricity is generated by photovoltaic solar energy. A 12% market share would provide savings of 196 million tons of CO2 emission every year. The main reason for low adoption of PVs is the high cost and, therefore, growth has been mainly driven by government subsidies, which are now declining.
Organic solar cells (OPV) could provide a step change in production costs and make clean solar energy use ubiquitous. A major challenge in the development of OPVs is how to correlate the nanoscale morphology of the active layer to the device performance. The active ultrathin layers are formed of two components that phase separate with domains in the order of tens of nanometres.
Different processing and post processing strongly affects the morphology and therefore the device efficiency, making scaling up from laboratory to industrial production very challenging. Currently, there is no technique that can provide morphological and electrical information of the 3D layer with nanometre resolution.
In this lecture, I-ll present NPL's significant step in this direction. We have demonstrated that photoconductive atomic force microscopy (PC-AFM) can provide both surface and subsurface information of operating organic solar cells, providing a way to directly correlate nanostructure with overall device performance.