One-dimensional semiconductor nanowires with strong quantum confinement effect re of great interest for applications in advanced optoelectronics and photochemical conversions. Beyond the state-of-the-art Cd-containing ones, have shown the utmost potential for next-generation environmental-friendly applications.
But ZnSe nanowires produced so far are largely limited to the strong quantum confinement regime with near-violet-light absorption or to the bulk regime with undiscernible exciton features. Simultaneous and high-precision manipulations on their radial and axial sizes have so far been challenging. It substantially impedes their further applications.
The study was published in National Science Review. Scientists from University of Science and Technology of China (USTC) have reported the on-demand synthesis of high-quality and blue-light-active ZnSe QWs by developing a flexible synthetic approach. It is a two-step catalytic growth strategy that enables independent, high-precision and wide-range controls over the diameter and length of ZnSe QWs. Scientists were able to bridge the gap between prior magic-sized ZnSe QWs and bulk-like ZnSe nanowires.
Scientists found that a new epitaxial orientation between the cubic-phase catalyst tips and wurtzite ZnSe QWs kinetically favors the formation of ultrathin and stacking-fault free QWs. The strong quantum confinement, high-degree size control, and the absence of mixed phases together lead to their well-defined and ultranarrow excitonic absorption in the blue-light region with full width at half maximum (FWHM) of sub-13 nm. Scientists further eliminated the surface electron traps in these ZnSe QWs which resulted in long-lived charge carriers and high-efficiency solar-to-H2 conversion.
The two-step catalyzed growth strategy is believed to be general for a variety of colloidal nanowires. The access to those high-quality nanowires would thus offer a versatile material library for heavy-metal free applications in solar fuels and optoelectronics in the future.