Improving Photovoltaic Performance of All-Polymer Solar Cells by Adding An Amorphous B←N Embedded Polymer as the Third Component.

Currently, most of the disclosed ternary strategies to improve photovoltaic performance of all-polymer solar cells commonly focus on the guest polymers having similar structures with the host polymer donors or acceptors. Herein, we develop a distinctive ternary method that adding an amorphous B←N embedded polymer named BN-Cl-2fT to a crystallized host polymer blend of PM6 and PY-TT (a copolymer of Y6 and thieno[3,2-b]thiophene). Although the structures between BN-Cl-2fT and PM6 and PY-TT are completely different, excellent miscibility is found between BN-Cl-2fT and both of the host PM6 and PY-TT, which can be interpreted by the crowded phenyl groups anchoring along the backbone of BN-Cl-2fT, leading to weak self-aggregation. GIWAXS measurements explicitly confirm the crystallization of PM6 and PY-TT and amorphous feature of BN-Cl-2fT. Furthermore, adding 10 wt% BN-Cl-2fT to PM6:PY-TT could significantly enhance the crystallization of the host polymers. Thus the ternary devices based on PM6:PY-TT:BN-Cl-2fT afford promoted J SC (23.29 versus 21.80 mA/cm 2 ), FF (62.4% versus 60.0%), and PCE (13.70% versus 12.23%) in contrast to these parameters of binary devices based on PM6:PY-TT. We provide a unique and enlightening avenue to design high performance all-PSCs by adding amorphous B←N embedded polymers as guest component to enhance host-crystallization. This article is protected by copyright. All rights reserved.