Increasing Exfoliation Yield in the Synthesis of MoS₂ Quantum Dots for Optoelectronic and Other Applications through a Continuous Multicycle Acoustomicrofluidic Approach

We show that the synthesis yields of transition-metal dichalcogenide (TMD) quantum dots (QDs)—in particular, that of molybdenum disulfide (MoS2)—can be improved through a miniaturized continuous multicycle microfluidic process. The process exploits the unique piezoelectricity of two-dimensional (2D) TMDs by employing the strong electromechanical coupling inherent in a novel acoustomicrofluidic nebulization process to delaminate and laterally cleave the bulk TMD material into QDs. In particular, we show that by carrying out the process in a closed system the nebulized aerosols containing the exfoliated QDs recondense and are repeatedly renebulized. With each successive nebulization–condensation–renebulization cycle, the QDs are progressively thinned and become increasingly uniform in their lateral dimension. Over just four 10 min cycles, the yield of predominantly single-layer QDs with a mean lateral dimension of 8.25 ± 4 nm is 10.7 ± 2% with a single chipscale device, which is considerably higher than the typical 2–3% yields obtained with conventional synthesis methods. Given the simplicity, low cost, and miniaturizability of the technology, the process can be easily parallelized for high production throughput commensurate with industrial-scale synthesis for a wide range of applications across optoelectronics, photocatalysis, energy storage, photonics, and biosensing, among others.