The advancement of solution-processed optoelectronics critically demands functional inks that combine solution stability, processability, and optoelectronic properties. PbS quantum dots (QDs) capped with lead iodide (PbS-PbI 2 ) are the leading materials for near-infrared photovoltaics and photodetectors, yet their ink development has been hindered by the lack of suitable solvents. Achieving dispersibility of PbS-PbI 2 requires a strong-coordinating solvent, butylamine (BA), which unfortunately inevitably etches the QD surface. Although prior efforts reduced the BA content via co-solvent engineering, ink stability has only been extended to about one week.
The research groups of Prof. Xintong Zhang and Prof. Yinglin Wang at Northeast Normal University, in collaboration with Prof. Heedae Kim at Jeonbuk National University, reported a vapor-assisted pre-solvation strategy to break the stability bottleneck of PbS-PbI 2 inks. Instead of dispersing the dots in liquid BA, they subjected the PbS-PbI 2 quantum dot solids to a short-time treatment with low-boiling-point butylamine (BA) vapor. This transient treatment induces dissociation and solvation of the dense PbI 2 ligand shell on the QD surface, after which the residual BA is completely removed by evaporation. The treated QDs can be dispersed directly in amine-free polar solvents such as N-methylpyrrolidone to form highly stable inks. Critically, because the vapor exposure avoids sustained liquid‑phase contact, this strategy substantially suppresses the chemical etching that otherwise compromises the QD surface integrity.
Compared with conventional BA‑solvent‑based QD inks, the new PbS-PbI 2 QD inks exhibit a markedly reduced trapstate density and a prolonged carrier recombination lifetime, as evidenced by photophysical characterization. More importantly, the resulting PbS-PbI 2 inks exhibit no detectable change in average particle size after ambient storage for over 60 days, demonstrating colloidal stability far beyond any previously reported BA‑based system.
This enhanced stability translates directly into device performance. Solar cells fabricated from inks stored for 60 days still deliver a power conversion efficiency of 10.8%, retaining approximately 90% of the efficiency obtained from freshly prepared inks. In contrast, conventional BA inks degrade rapidly, causing the efficiency of the control device to drop to 0.3% within 4 h.
The vaporprocessed ink also exhibits excellent thermal robustness, withstanding temperatures up to 80 ℃, and is compatible with large‑area deposition techniques. The team successfully demonstrates uniform bladecoated films over an area of 100 cm 2 , confirming its potential for scalable manufacturing.
This work effectively decoupled the long-standing trade-off between solubility and stability in PbSPbI 2 ink development. By eliminating BA from the final ink formulation while retaining its initial role in surface solvation, this strategy achieves PbS-PbI 2 inks with exceptional stability, high device efficiency and large-area solution processability, thereby offering a reliable ink platform for scalable solution‑based manufacturing of high‑performance QD optoelectronic devices.
Other contributors include Xiaofei Li (first author), Zihan Wang, Zhixiang Gui, Chao Wang, Hao Li, Xiaochen Guo, Yanlong Lu, Jiabao Lu, and Lingling Wang from Northeast Normal University, and Seungkwon Jeon, Seungmin Jeong, and Heedae Kim from Jeonbuk National University.
The work was supported by the Jilin Provincial Scientific and Technological Development Program [20250205062GH], the National Natural Science Foundation of China [62074031, 52273236, U22A2078, and 51872044], the 111 Center [B25030], and the Fundamental Research Funds for the Central Universities [2412025ZX002, 2412025YJ004], as well as the National Research Foundation (NRF) of Korea funded by the Korean government [RS-2023-NR076826, RS-2025-25396280], and the Global-Learning & Academic Research Institution for Master’s, PhD students, and Postdocs Program [RS-2024-00443714].
DOI Link:
https://doi.org/10.26599/NR.2026.94908957
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Nano Research
Vapor-assisted pre-solvation breaks stability limitation of PbS QD inks
27-Aug-2026