Self-Sensitized Photooxidation in Extended Tetrathiafulvalenes

Photostability of organic dyes is a critical challenge in the field of organic photovoltaics, as prevalent exposure to light and air can lead to degradation of the active ingredient. In our study, a series of novel 2,1,3-benzothiadiazole-based extended tetrathiafulvalenes was synthesized and assessed for their photophysical properties. Extended tetrathiafulvalenes are promising candidates for dyes in organic photovoltaics, yet the role that dithiafulvene plays in singlet molecular oxygen sensitization remains unclear. Photophysical analyses show a clear link between dithiafulvene units and a decreased generation of molecular singlet oxygen, which further results in a [2 + 2] cycloaddition reaction and cleavage of the said unit.