Direct Laser Pruning of CdS_<i>x</i>Se_1–<i>x</i> Nanobelts en Route to a Multicolored Pattern with Controlled Functionalities

CdS_<i>x</i>Se_1–<i>x</i> nanobelts are interesting nanostructured materials with a tunable band gap from 1.7 to 2.4 eV depending on the nanobelts' stoichiometry. On the basis of their chemical compositions, these nanobelts give out strong photoluminescence with unique color. In this work, we demonstrate that a direct focused laser beam irradiation was able to achieve localized modification of the chemical composition of the nanobelts. As a result, we could locally change the optical properties of these nanobelts. With a scanning laser beam, micropatterns with a wide range of fluorescence color could be created on a substrate covered with ternary nanobelts without a prepatterned mask. The laser modified nanobelts showed higher resistance to acid corrosion and these nanobelts exhibited more superior photoconductivity. The construction of micropatterns with functionality/color control within the sample would provide greater building blocks for photoelectronic applications

Field Emission from Decorated Carbon Nanotube–QDs Microstructures with a View to the Dominant Electron Paths

We present a study on the field emission properties of a hybrid system comprised of carbon nanotube (CNT) micropillars decorated with quantum dots (QDs). With controlled decoration of QDs on the CNT micropillars through a simple assisted self-assembly process, further enhancement in the field emitting property of the hybrid microstructures was detected. Upon irradiation of the hybrid structure with a broad visible-light laser beam, additional enhanced field emission was observed. Analyses using fluorescence and confocal microscopy, as well as ultraviolet photoelectron spectroscopy, suggested that electron transfer from QDs to the CNT strands and the reduced work function of the hybrid system as the contributing factors behind the enhanced field emissions. In addition, we discovered that the field emission process gave rise to lost of the QDs’ fluorescence luminosity on the microstructures in specific patterns attributable to transfers of charge carrier from QDs to the CNTs. This observation provided a new means to understand and to determine the predominant 3D path of the emission of electrons from the sample down to a micrometer scale level