Preparation And Optical Properties Of Micro/Nano-structured Zinc Oxide

ZnO shows excellent properties and a various of micro/nano-structured ZnOcan be readily achieved by many methods, which make it a promising material forwidespread application in pigments of coating, solar cells, pressure-sensitive andgas-sensitive elements, light-emitting diodes and lasering, piezoelectric device,ultraviolet detector and sensors and so on. In addition, ZnO holds high resistance toradiation damage making it suitable to space application.In recent year, although constant progresses have been achieved, controlledsynthesis of micro/nano-structured ZnO materials and the design and fabrication ofphoto-electric devices with excellent performance and high device stability are stillchallenging for further development and industrial application of ZnO materials. Inthis regard, this work is mainly focused on the controlled synthesis of the ZnObased micro/nano-partials with core-shell structure, ZnO nano-structured films withdesired optical properties and morphology. In addition, based on the differentproperties of the above-mentioned ZnO materials are explored to serve as thepigments of thermal control coating and the cathode buffer layer of invertedpolymer solar cells, respectively. The contents of this work are listed as following:ZnO based composited pigments with micro/nano and core-shell structure havebeen designed and fabricated. Fabrication and optical properties of the ZnO basedcomposited pigments are investigated, and the optical stability of the compositedpigments under the irradiation of space charge particles is also studied. It has beenfound that the ZnO-based composite pigments hold both high spectral reflectanceand good optical stability under the simulated space irradiation of protons andelectrons. Based on the analysis results of XRD patterns and spectral reflectance, ithas been found that the composite pigment contain67%Zn₂SiO₄shell layer exhibitsthe lowest change in solar absorptance, a37%decrease compared to that of theas-received ZnO pigments, the best optical stability under protons irradiation wasachieved.The mechanisms under the excellent optical stability of the composite pigmentirradiated by space charged particles are investigated. It has been demonstrated thatthe Zn₂SiO₄surface layer could effectively reduces the quantity of the irradiationinduced defects in ZnO substrate by absorbing part of the energy of the incidentparticles, and thus further improving the optical stability of the composite pigment.In addition, it has found that the optical stability of Zn₂SiO₄shell layer is better thanthat of as-received ZnO pigments to some extent, which partly enhanced the optical stability of the composite pigments.ZnO nano-films with controlled morphology, thickness and transmittance arefabricated by using an improved sol-gel method. The fabrication and devicesperformance of the inverted polymer solar cells with ZnO nano-films as a cathodebuffer layer are also investigated. The influence of the morphology, thickness andtransmittance of ZnO nano-films on the performance of inverted polymer solar cellsare systematically investigated. It has been demonstrated that, in a certain thicknessrange, the device performance is strongly dependent on the ZnO morphology ratherthan thickness and transmittance. The morphology of the ZnO nano-films plays adirect and important role in the contact quality between P3HT: PCBM active layerand ZnO, and thus impact on the fill factor and power conversion efficiency of theinverted devices. Inverted devices with a dense and homogenous ZnO buffer layerderived from0.1M sol exhibit an power conversion efficiency of3.3%which is a32%increase compared to devices with a rough ZnO buffer layer made from1Msol, which exhibited a power conversion efficiency of2.5%.A route based on the chemical solution deposition at low temperature isdesigned to fabricate the ZnO nanowall arrays. The films with super dense ZnOrods are prepared by increasing the precursor concentration and decreasing thegrowth temperature and initial temperature of solution. The nanowall formation isascribed to selective dissolution of （001） planes of chemical bath deposited denseZnO rods The ZnO nanowall arrays are firstly explored as an electrons collectinglayer in inverted polymer solar cells. The primary result shows that the aqueousgrowth ZnO NW networks with a potential to serve as a new electrode for thefurther development of inverted polymer solar cells.