Photophysical studies of poly-isocyanopeptide based photovoltaic blends

We report a photophysical study of photovoltaic blends containing perylene-substituted polyisocyanide (pery-PIC) materials, using time-correlated single photon counting and photo-induced absorption spectroscopy, and compare the key characteristics with analogous perylene-diimide (PDI) monomer blends with polythiophene- and polyfluorene-based conjugated polymers. Pery-PIC consists of semiconducting perylene units, which self-stack in a regular fashion around a rigid helical poly-isocyanopeptide backbone. In particular, the charged state lifetimes in pery-PIC blends are found to be of order tens of microseconds, this being typically less than half those of the perylene anion in the corresponding PDI blends. We consider the influence of photophysical factors on the superior photovoltaic device performance of the pery-PIC blends, relative to the corresponding PDI-based devices, in addition to the morphological effects described in earlier studies.