Diketopyrrolopyrrole latent pigment-based bilayer solar cells

Two Diketopyrrolopyrrole based latent pigment donor materials were fabricated into thin film bilayer photovoltaic devices featuring PCBM as the acceptor. Thermal deprotection of the thin film, carried out at 200? C, returns the dye-like small molecule to the corresponding pristine pigment quantitatively. The connected evolution of electrical and morphological features of pure thin films and blends are examined. A significant decrease in extinction coefficient was noted and correlated both to intrinsic changes of the electronic structure upon cleavage and to an increase in internal scattering due to extensive crystallization. Power conversion efficiencies of 0.33% were achieved for bilayer devices, nearly doubling previous results with latent pigment DPP devices, under comparable experimental conditions.