Sb₂S₃/Sb₂Se₃ Nanostructures and Applications

Abstract

This dissertation reports the progress made in the fabrication of nanostructured Sb2S3/Sb2S3-xSex nanostructures and their associated photovoltaic applications. The features of my study are the synthesis of Sb2S3/Sb2S3-xSex nanoparticles by hot-injection method, direct/indirect nanopatterning of the Sb2S3/Sb2S3-xSex film by direct laser interference method and the fabrication of 2D/3D Sb2S3/Sb2S3-xSex nanostructure by electron beam lithography technology. Chapter 1 gives an overview of the materials synthesis, nanopatterning technology as well as photovoltaic characterization methods that were adopted in my study. Chapter 2 mainly emphasized on the Sb2S3/Sb2S3-xSex nanoparticles obtained by hot-injection method and the associated photovoltaic applications. Amorphous Sb2S3 nanospheres dispersed in chlorobenzene can be used as "inks" for the fabrication of Sb2S3 thin film by simple spin-annealing procedure. Such Sb2S3 "ink" has the advantages of facile to use and ready to use at any time. Sb2S3 nanospheres can also be synthesized in situ on the surface of mesporous TiO2 seed layer. The Sb2S3 thin film obtained by the in situ growth method is featured as compact and rendered higher power conversion efficiency than the Sb2S3 film fabricated by spin-annealing method. Chapter 3 is mainly about introducing periodic 2D structures to the Sb2S3/Sb2S3-xSex solar cells. Micrometer sized patterns were transferred to amorphous Sb2S3/Sb2S3-xSex layers, crystalline Sb2S3 layers and P3HT covered crystalline Sb2S3 layers by direct laser interference patterning. Although photovoltaic performances improvement was observed from laser patterned Sb2S3/P3HT devices, absorption enhancement induced by periodic structure was not observed, which was in coordinate with the finite difference time domain simulation result. Chapter 4 is featured as using electron beam lithography method to fabricate Sb2S3/Sb2S3-xSex nanostructures. The Sb2S3/Sb2S3-xSex precursor films obtained from fast chemical approach method can act as negative electron resist. High resolution 2D/3D Sb2S3/Sb2S3-xSex nanostructues can be fabricated by electron beam illumination with designed pattern on the precursor film. Light sensing property of the as synthesised Sb2S3-xSex nanoribbon is presented. Periodic 2D structure composed of Sb2S3 nanolines with 700 nm periodicity were successfully fabricated on the surface of FTO/TiO2/compact Sb2S3 heterostructure. The periodic structure induced absorption enhancement and transmittance spectrum modification were observed. Furthermore, the finite difference time domain simulation results also underline the experimental findings.