Interfacial Engineering of PEDOT:PSS with Weyl Semimetals NbAs and NbP for High-Performance Organic Solar Cells

Interface engineering is one of the key factors driving the efficiency of organic solar cells (OSCs) beyond 20%, with regulation of the hole transport layers (HTLs) being particularly critical. However, as the current mainstream HTL material, PEDOT:PSS suffers from intrinsic limitations, including strong acidity, restricted conductivity, and weak electron-blocking capability, which have become bottlenecks hindering further performance breakthroughs in OSCs. Therefore, this study proposes a PEDOT:PSS doping strategy based on Weyl semimetals NbAs and NbP. NbAs and NbP nanoflakes were obtained through liquid-phase exfoliation and incorporated into PEDOT:PSS, wherein their introduction weakens the Coulomb interaction between PEDOT and PSS chains, promoting phase separation and PEDOT network reconstruction. Concurrently, the topologically protected surface states of the Weyl semimetals facilitate the formation of additional fast charge transport pathways, enhancing both the conductivity and carrier mobility of the composite HTL. Consequently, devices employing the composite HTL deliver a champion efficiency of 17.32% for PM6:Y6 and further reach 19.32% and 20.18% in PM6:L8-BO and D18:L8-BO systems, demonstrating excellent universality across different active layers. Moreover, NbAs/NbP incorporation reduces the PEDOT:PSS acidity and significantly improves device stability. This study represents the first incorporation of Weyl semimetals into a PEDOT:PSS HTL, providing valuable insights for constructing high-efficiency and stable OSCs.