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 × 10 ¹¹ 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.