Hydrogen-Bond Mediated Synthesis of Conductive Quantum Dots for All-Ink Optoelectronic Devices.

Abstract

Short-chain molecular ligands (SMLs) are favored for producing colloidal quantum dot (CQD) inks for solution-processed optoelectronics, since they enable more efficient charge transport than conventional long-chain ligands. However, their weak steric or electrostatic stabilization makes CQD inks vulnerable to aggregation or coalescence. To overcome this challenge, here we report a hydrogen-bond-mediated strategy for preparing SML-capped CQD inks with excellent colloidal stability and solution processibility. Through theoretical and experimental evaluation of hydrogen-bond strengths across polar organic solvents and small thiol molecules, we identify 1-thioglycerol (TG) in dimethylsulfoxide (DMSO) as an optimal pair. This combination enables one-step synthesis of CQDs of binary, ternary, and quaternary metal sulfide under ambient conditions, while strong ligand-solvent hydrogen bonding ensures robust colloidal stability. Optoelectronic devices fabricated by stacking these p-type PbS CQDs on n-type PbS CQDs achieve a record power conversion efficiency of 12.2% solar cells in all-ink-processed devices and an enhanced detectivity of 9.4 × 10¹¹ Jones in near-infrared photodetectors. This hydrogen-bond-mediated approach demonstrates a straightforward and cost-effective route to produce p-type PbS CQD conductive inks, holding great promise for advancing all-ink scalable-manufacturing optoelectronic devices.