PbS Quantum Dots Ink with Months-long Shelf-lifetime Enabling Scalable and Efficient Short-wavelength Infrared Photodetectors.

The phase-transfer ligand exchange of PbS quantum dots (QDs) has substantially simplified device fabrication giving hope for future industrial exploitation. However, this technique when applied to QDs of large size (> 4 nm) gives rise to inks with poor colloidal stability, thus hindering the development of QDs photodetectors in short-wavelength infrared range (∼1000-3000 nm). Here, we demonstrate that methylammonium lead iodide ligands can provide sufficient passivation of PbS QDs of size up to 6.7 nm, enabling inks with a minimum of ten-week shelf-life time, as proven by optical absorption and solution-small angle X-ray scattering. Furthermore, the maximum linear electron mobility of 4.5 × 10 -2 cm 2 V -1 s -1 was measured in field-effect transistors fabricated with fresh inks, while transistors fabricated with the same solution after ten-week storage retained 74% of the average starting electron mobility, demonstrating the outstanding quality both of the fresh and aged inks. Finally, photodetectors fabricated via blade-coating exhibited 76% external quantum efficiency at 1300 nm and 1.8 × 10 12 Jones specific detectivity, values comparable with devices fabricated using ink with lower stability and wasteful methods such as spin-coating. This article is protected by copyright. All rights reserved.