Electron mobility of non-fullerene acceptors using a time of flight method

Abstract

Organic solar cells are a promising renewable energy technology, offering the advantages of mechanical flexibility and solution processability. The charge carrier mobility is an important parameter as it influences the competition between charge extraction and recombination and therefore the cell efficiency. We report the electron mobility of two high performance non-fullerene acceptors ITIC and IDTBR in neat films and blended with their common donors. In a pure film ITIC has a zero-field electron mobility of 7.4 × 10−4 cm2/Vs, which dropped to 1.0 × 10−4 cm2/Vs when put into a blend with PTB7-Th or P3HT. The IDTBR:P3HT blend was found to have a slightly lower electron mobility of 5.6 × 10−5 cm2/Vs. The measured electron mobility is the same order of magnitude as the hole mobility in these blends, leading to balanced transport and efficient photovoltaic cells.