Morphology Control Realizes Fast Charge Dissociation and Transport in High-Performance All-Polymer Solar Cells
Yushou Zhao, Junying Wu, Wenming Li, F. Xiao‐Feng Qin, Menglan Lv, Yong Hua, Weiguo Zhu, Zhicai He, Bin Zhang
Abstract
The difficulty in controlling the morphology of the active layer is a major factor for hindering the improvement of photovoltaic performance in all-polymer solar cells (all-PSCs). Here, we introduced two kinds of high-boiling-point solvent additives, 1,8-diiodooctane (DIO) and 1-chloronaphthalene (CN), to control the donor/acceptor blends, thereby improving the film formation and crystallization kinetics and molecular orientation of the active layer in all-PSCs. In this study, the effectiveness of high-boiling-point solvent additives in controlling the morphology of the active layer is examined. Moreover, it was found that the selectivity of additives affected the photovoltaic performance in all-PSCs, and improper additives could significantly reduce the power conversion efficiencies (PCEs). Through using an all-polymer system with D18-Cl as the polymer donor and PY-IT as the polymer acceptor, the CN-treated device exhibited poor PCE, while those employing DIO significantly improved the phase separation morphology of the active layer, resulting in an impressive PCE of 16.0%. Importantly, the DIO-treated device in the D18-Cl:PY-IT system could realize the faster charge dissociation and transport as well as lower bimolecular recombination. Furthermore, the corresponding devices exhibited excellent storage stability, retaining over 80% of their initial efficiency after 3000 h in a nitrogen-atmosphere glovebox, which was potentially beneficial for the future commercial application.