One-Step Directly Synthesized Dual-Ligand PbS Quantum Dot Inks via Heterocyclic Ligand Coordination for Efficient Hole Transport Layer

Abstract Hole transport layers (HTLs) in colloidal quantum dot (QD) solar cells are conventionally prepared through multi-step ligand exchange processes, which often induce surface damage and trap-state defects. To address these limitations, this work presents an inorganic–organic in situ synergistic passivation strategy for the one-step synthesis of a stable dual-ligand p-type PbS QD conductive ink. Employing lead thiocyanate (Pb(SCN)2) as the precursor together with 2-furanmethanethiol (FMT) as the synergistic ligand enables the formation of a dual-ligand co-adsorption network. The resulting PbS QD conductive ink forms a p-type conducting interfacial layer with favorable cascade energy-level alignment and reduces the trap-state density (tDOS) by approximately 38%. Utilizing this directly synthesized p-type PbS QD conductive ink as the HTL, the resulting solar cells achieve a champion power conversion efficiency (PCE) of 13.60%, enabled by prolonged carrier lifetimes and accelerated charge extraction kinetics. This work establishes a practical chemical design strategy for engineering PbS QD interfaces and simplifying HTL fabrication.