Controlled Formation Of Organic Microrods/Tubes By Manipulating The Kinetics Of Chemical Reactions And Optoelectronic Applications Of Squaraine Microwire/Silicon P-N Heterojunction Based Photodetector

Nanostructures of small-molecule organic materials have aroused intense interestin the field of novel optoelectronic devices due to their tunable electronic and opticalproperties. However, it still remain a great challenge to well controll the morphologiesof the resulting nanostructures, as it is very hard to precisely control the complicatednucleation process at the initial stages and the subsequent fast growth process.（1） Wehave demonstrated controlled preparation of Ni（DMG）₂microrods/tubes via chemicalreaction method. By manipulating the reaction kinetics via the concentration ofreactants, shapes of the resulting microstructures can be easily tuned from microrods tomicrotubes. It was proposed that under high reactants’ concentrations, molecules willprefer to grow at corners or edges of nuclei with high free energies, to reduce the totalenergy in the system, which would lead to partial or complete hollow interiors andeventually resulted in mircotubes. The fact that DMG show high selectivity with Ni2+and accompanied with obvious color change enable us to fabricate test strip fornaked-eye detection of Ni2+. Benefit from the large surface areas of DMG nanoparticleson the test strip, the detection limit is improved by two orders over that of conventionalsolution method. This strategy is sensitive, simple and easy to handle, thus expected topossess potentials for the practical Ni²⁺detection applications.（2） SQ microwire/Silicon P-N heterojunction was constructed via a convenient route. A substrate withprefabricated electrode arrays was immersed vertically into a SQ/CH₂Cl₂solution （10mL,9mg/L） in a serum bottle at10℃. After the dichloromethane have evaporatedcompletely, SQ microwire can be properly deposited across the electrodes, andheterojunction was successfully constructed. SQ microwire can firmly adhere toelectrodes, thus small contact resistance exist. As a result, the heterojunction exhibited pronounced rectification characteristics with rectification ratio larger than10³at±5V inthe dark. The response of SQ microwire/Silicon P-N heterojunction to the visible lightwas fast and exhibited long-term stability and repeatability. It is expected that the SQmicrowire/Silicon P-N heterojunction will have good application prospects in futurephotoelectronic detections.