Non-fullerene acceptors based on multiple non-covalent interactions for low cost and air stable organic solar cells

Abstract Significant progresses have been made on organic solar cells (OSCs) in last few years, but the industrialization of OSCs is still hindered by high cost and poor device stability. Recently, the most successful OSCs are usually based on fused-ring small molecule non-fullerene acceptors (SM-NFAs) which often involve multiple complex synthetic steps and result in low overall yields and high cost. Herein, two easily accessible non-fused NFAs based on BT, CPDT and IC with different halogen atoms named BT-F and BT-Cl were designed and synthesized. Non-covalent interactions or conformation locks between BT and adjacent CPDT units provided planar conformations, which is beneficial for molecular packing and charge transport. When blended with low cost polymer donor PTQ-10, optimal devices based on BT-F provided a PCE of 8.26%. A higher PCE of 8.65% was obtained from BT-Cl-based devices. Low voltage loss of 0.57 and 0.59 V were observed for BT-F- and BT-Cl-based devices. It is noteworthy that devices based on PTQ-10:BT-F and PTQ-10:BT-Cl exhibited excellent stabilities when stored in ambient atmosphere for 10 days without encapsulation. This work demonstrates an example of pursuing low cost OSCs with excellent air stability.