Solution‐Processable Two‐Dimensional MoSe2 Quantum Dots as a Hole Transport Layer for Highly Efficient and Stable Nonfullerene Organic Solar Cells

Abstract

Hole transport materials are critical to carrier separation, hole extraction, and stability of organic solar cells (OSCs). Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been popularly used as hole transport layers (HTLs) in high‐efficiency OSCs, while the device stability is relatively low due to interfacial chemical reactions between active layer and PEDOT:PSS. Herein, two‐dimensional MoSe2 quantum dots (QDs) are employed as a subphoto sensitizer and pinhole‐free HTL to replace PEDOT:PSS in OSCs. The power conversion efficiencies of PBDB‐T: 3,9‐bis(2‐methylene(3‐(1,1‐dicyanomethylene) ‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)dithieno‐[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene (ITIC), PM6:Y6, and PM6:L8‐BO‐based OSCs with MoSe2 QDs HTLs are 9.34%, 15.36%, and 18.29%, respectively, which are comparable to those (9.31%, 15.51%, and 18.22%) of the control devices with PEDOT:PSS HTLs. More importantly, superior device stability is achieved in the OSCs with MoSe2 QDs HTLs due to suppressed interfacial chemical reactions. These results indicate that ultrathin MoSe2 QDs are a promising candidate material for HTL, providing a novel approach to further improving the performance of OSCs.