Simultaneously enhancing the performance and mobility of organic solar classical systems by a novel additive

In the classical system of inverted organic solar cells (PTB7-Th:PC71BM), modulating the phase separation in the vertical direction has a large effect on the mobility of the carriers. Hence, we report a novel additive 4-Chloroanisole (4CAS) doped in the active layer to modulate this phase separation. Since the additive solubilizes the fullerene acceptor, the molecules of the acceptor and donor are rearranged and self-assembled in an ordering way. As a result, bimolecular recombination, trap-assisted recombination is inhibited and the carrier lifetime has been extended by nearly two times. In combination with the enhanced carrier mobility, the device based on the classical system realizes power conversion efficiency (PCE) of 9.39% and an FF is more than 70%. Our work provides a possible method for modulating the phase separation in the vertical direction to simultaneously improve PCE and mobility of the device.