In‐situ study of degradation in <scp>PTB7</scp>:<scp>PCBM</scp> films prepared with the binary solvent additive <scp>DPE</scp>:<scp>DIO</scp>

Abstract Blend films of poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b']dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl]] (PTB7) in combination with 6,6‐phenyl‐C61‐butyric‐acid‐methyl‐ester (PCBM) are a model system for low bandgap organic photovoltaics. Typically, solvent additives used to improve the power conversion efficiencies resulting devices but possibly also decrease device stability. In this study, we use binary additive 1,8‐diiodooctane:diphenylether (DIO:DPE) PTB7:PCBM blend and study how different film drying procedures influence physical chemical stability polymer blend. The strong procedure on against photoinduced degradation films, produced additives, is shown data from UV–visible (UV–vis), Fourier transform infrared (FTIR) Raman spectroscopy. addition molecules DIO:DPE accelerates compared pristine At higher annealing temperature removal bringing back level which promising photovoltaic applications.