Photodegradation Study of Organic Photovoltaics using time-resolved Electrostatic Force Microscopy (trEFM)

Organic photovoltaics (OPVs) offer the potential for solar cell technology that can be manufactured at a low cost and on a large scale. However, a limiting factor for OPV devices is their lifetime. Photooxidation leads to degradation of the active layer of OPVs by formation of charge traps and contributes to shorter lifetimes. The mechanisms of active layer degradation were investigated by photooxidizing bulk heterojunction thin films with different polymer blends, PFB:F8BT and P3HT:PCBM, at specific wavelengths and performing attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Additionally, we used time-resolved electrostatic force microscopy (trEFM) and fast-free trEFM (FF-trEFM), optoelectronic scanning probe techniques with nanoscale resolution, to measure the relative efficiencies of specifically photooxidized areas of the films. Our results suggest that these techniques can be used to study the kinetics of trap formation under different conditions.