Mechanochemical Synthesis of Amorphous MoO_3-x Quantum Dots for All-In-One Electrochromic Devices

Electrochromic metal oxides enable dynamic regulation of color and light transmission, offering significant potential for smart windows and energy-efficient displays. However, the widespread of electrochromic devices suffers from poor cost-effectiveness due to the intricate material synthesis processes and complex device structure. Herein, the study presents a mechanochemical method for mass-producing amorphous MoO_3-x quantum dots (QDs) with abundant oxygen vacancies. Through combined shear exfoliation and chemical oxidation of MoS₂ precursors, ligand-free QDs (4.4 nm average size) are achieved under ambient conditions. Moreover, the innovative all-in-one electrochromic device is designed based on the amorphous MoO_3-x QDs film, which greatly simplifies the device construction and fabrication process. Due to the facilitated ion transport inside the amorphous MoO_3-x QDs, the resulting device exhibits excellent performance, including a large transmittance modulation (ΔT = 84.2% at 600 nm), high coloration efficiency (97.5 cm² C⁻¹) and long-term stability (90.2% after 400 cycles). Furthermore, the study demonstrates an energy-efficient electrochromic display with low driven voltage (1 V), high contrast, as well as the prolonged optical memory effect up to 7 days. These results not only provide a scalable mechanochemical synthesis route for defect-engineered metal oxide QDs but also open new opportunities for the development of energy-saving electrochromic displays.