Twisted GeS Nanowire with Engineered Stacking Order and Tunable Composition

One-dimensional (1D) nanoarchitectures crafted from van der Waals (vdWs) layered crystals with unconventionally stacking orders have demonstrated novel and inspiring properties. Recently, helical germanium sulfide (GeS) crystals with discretely twisted structures are grown, inducing interlayer twist. Here, 1D twisted nanowires with engineered stacking order and bandgap are further prepared. Due to the axial screw dislocation, the crystallized GeS layers rotate to form twisted nanowires during the vapor−liquid−solid (VLS) process. Moreover, substitutional alloying of germanium selenide (GeSe) not only allows for a tunable bandgap, but also preserves the intrinsic twist in the alloy nanowires. Unlike normal nanowires, the pronounced second harmonic generation (SHG) signal definitely confirms broken inversion symmetry caused by the atypical stacking order. Enhanced photoelectronic properties are observed in these twisted GeS nanowires. The findings present significant opportunities for future electronics and optoelectronics applications by harnessing 1D vdWs nanoarchitectures with engineered stacking order and composition-controlled bandgaps.