Preparing The Light Absorbing Layer Of Perovskite Solar Cell And Synthesis Of Gallium Nitride Nanowire Arrays

The energy crisis has always been one of the biggest problem which the human must confront. Traditional energy sources such as coal and petroleum have generated huge carbon emissions, endangering global climate and our living environment. Thus, exploiting and utilizing of clean energy is particularly important in the current. Most of the energy on the Earth arrives from the Sun. Solar cells are the excellent clean energy technology that have achieved solar energy direct converting to electricity. In recent years, power conversion efficiencies(PCEs) of perovskite solar cell energy have improved rapidly, attracting researchers’ tremendous attention worldwide. Under this background, we prepared the light absorbing layer film of planar type of perovskite solar cell by solution-based spin-coating method in this thesis. Furthermore, we conducted a systematic inquiry into the impact on perovskite film’s coverage rate and absorption coefficient made by many factors such as the spin-coating process, annealed condition, different substrates, and component of precursor, which lead us to fabricate CH3NH3PbI3, CH3NH3PbI3-xClx film with high coverage rate. A clear fluorescence quenching effect on TiO2 layer was observed by steady-state photoluminescence. It laid the groundwork for production of perovskite solar cells. In detail, single step spincoating method processed with chlorobenzen will product flat CH3NH3PbI3 film with uniform grain size. Two step spin-coating method for preparing PbI2 film in advance also lead to CH3NH3 Pb I3 film with uniform grain size, N,N-dimethylformamide(DMF) joining in anneal process will bring in grains growing further. CH3NH3PbI3-xClx film prepared with different substrates and different annealing conditions shows different morphologies. Substrates with rough surface contributes to the high coverage, while lower annealing temperature results smoother film.Profiting from its superior properties, one-dimensional semiconductor materials have important applications in production of solar cells and high-performance electronic devices. GaN materials with its unique wide band, high breakdown voltage, high thermal conductivity, and high electron saturation rate, becomes the representative materials of the third-generation semiconductor. In chapter four, we adopted a simple chemical vapor deposition(CVD) method to synthesize GaN nanowires. By X-ray diffraction(XRD) and transmission electron microscope(TEM) characterization, it demonstrates that the Ga N nanowires we synthesized are single crystal with hexagonal c structure, and nanowires grow along the preferred orientation [0001]. Through scanning electron microscope(SEM) characterization, we discovered GaN nanowire catalyzed by different metal have different morphology. Moreover, we investigate the growth mechanism of GaN nanowires with special morphology. By controlling the reaction gas flow to transform Ga and N sources in an atmosphere, decreasing the thickness of the metal catalyst and other measures to increase the number of nucleation, we successfully grow the GaN nanowire arrays.