Efficient non-fullerene organic solar cells employing aqueous solution-processed MoO₃as a hole-transporting layer

Organic solar cell (OSC) has drawn considerable interest in recent decades owing to their advantages of light weight, flexible, large area and potentially low-cost. Employing an appropriate hole-transporting layer (HTL) into an OSC device has been proved as an efficient method to obtain high efficiency OSC due to the enhancement of the hole transporting and extraction of the device. In this work, aqueous solution-processed MoO₃(s-MoO₃) thin films were employed as HTLs to construct non-fullerene PM6:Y6 OSCs. The s-MoO₃thin film was prepared by using an aqueous solution process from an isopolymolybdate [NH₄]₆Mo₇O₂₄.4H₂O precursor followed by thermal annealing treatment to convert the precursor to MoO₃. The s-MoO₃HTL based PM6:Y6 device demonstrates a power conversion efficiency of 15.75%, which is 38% improved than that of the device with thermally evaporated-MoO₃as HTL and 8% improved than that of the device with PEDOT:PSS as HTL. The enhancement of the device performance could be attributed to the enhanced hole mobility and better band matching of the s-MoO₃HTL. Moreover, the s-MoO₃HTL based PM6:Y6 device exhibited higher device stability than those of the reference devices. Our finding indicates that this s-MoO₃film has great potential as efficient HTL for high performance non fullerene OSCs.