The Controllable Synthesis Of Zinc Oxide Micro/Nano Structure And The Application In Sensitized Solar Cells

As a typical wide bandgap semiconductor,ZnO has various application prospects in photovoltaic cells,pressure sensors,gas sensors,light-emitting diodes(leds)and laser materials due to its advantages of simple preparation methods,controlable crystal morphology,ligh electron mobility,large specific surface area,physical and chemical stability.In this thesis,we devoted to controlable synthesize ZnO micro/nano composite structure and study the performances of photoanode used in sensitized solar cells.The g-C3N4/ZnO nanoparticles,oriented-linked ZnO nanorods and single crystal-like ZnO hierarchical microspheres were respectively synthesized by low temperature solution method.Meanwhile,the growth mechanism and photovoltaic performances of these materials were systematically investigated.The main contents of our research are listed as-follows:(1)ZnO-C3N4 composites were prepared by an ultrasonic irradiation assisted monolayer dispersion.The study found that the g-C3N4 coverage increased the scope of visible light absorption and the composite structure constructed an energy gardeince between the band of ZnO photoanode and dye molecules to improve the electron injection efficiency.g-C3N4 protecting layer receded the acidic dye molecules corrosion on the surface of ZnO,which improved the Voc and Jsc of the device.Compare with the power conversion efficiency(PCE)of ZnO photoanode,a higher PCE of 4.5%was demonstrated,representing a ~40% improvement.(2)ZnO nanorods composed of orientation aligned nanopartilces were prepared through a solvent-thermal method.The influence of the reactant concentration on the size and crystallinity of OA-RODs were discussed.In addition,the growth mechanism and photovoltaic performances of QDSSC were also discussed in detail.It was found that OA-RODs could improves the quantum dots loading amount and light scattering ability to increase the capture of incident light.Moreover,it provided high electrone diffusion passway which suppress the recombination of the charge carriers.Therefore,the cells derived from OA-RODs exhibits a high short current ptotocurrent density(Jsc)of 13 mA·cm-2 which finally leads to a high PCE of 4.7%.(3)Metal Organic Framework(MOF-5)was adopted as precursor to prepare single-like crystal ZnO hierarchical microspheres via a solvethermal route.The as-prepared ZnO nanospheres composed of ZnO primary unit closely and orientationally linked together.When used as scattering layer in CdS/CdSe QDSSCs,the unique structure reduced the number of grain boundary in the membrane structure and accelerated the transport of the photoelectrons.In addition,the scattering layer increased the reflection of incident light and improved the collection efficiency of the photoelectrons,whcih leads to a high Jsc of 15.9 mA·cm-2,open circuit voltage(Voc)of 640 eV.Therefore,the PCE was promoted to 5.66%,indicating a ~40% improvement compared with Zn O nanoparticle photoanode.