Research On Emerging Solar Cells Based On TiO₂ Nanowire Arrays

In recent years,photovoltaic power generation has received great attention from academic and industrial circles as a means of directly converting solar energy into electrical energy.The further development of traditional silicon and compound semiconductor solar cells have limited due to high cost and complicated manufacturing processes.New generation photovoltaic devices,such as dye-sensitized solar cells?DSSC?and organic-inorganic perovskite solar cells?PSC?,with low-cost,easy-to-process,bendable,and compatible with roll and print preparation processes have become the research hotspots.TiO₂ is a N-type wide bandgap semiconductor which has been widely used in many new generation photovoltaic devices such as the skeleton structure of DSSC and the electron transport layer of PSC due to its environmental friendliness,energy level matching and surface modification flexibility.The design and regulation of the structure,composition and interface of TiO₂layer are important for enhancing photon capture,reducing interface recombination,and ultimately improving the performance of solar cells.However,there is still no systematic and in-depth research in this area.Based on this,this paper mainly carries out the following research contents:?1?.TiO₂ nanorods?nanowires?arrays were prepared on a transparent conductive substrate by low temperature hydrothermal method.The effects of growth time,additives and precursors on the morphology,structure,composition and optical properties of TiO₂nanostructures were systematically studied.The results show that the length of TiO₂nanorods can be controlled by changing the growth time and the morphology of TiO₂nanorods can be controlled by changing the composition of growth solution with ethanol as additive.When the content of ethanol additive exceeds 10 mL,a dense rutile TiO₂ film is formed.DSSC based on a TiO₂ nanorod with a length of 1.2?m achieved 1.88%power conversion efficiency.?2?.Rutile nanowire arrays with length of 8.4?m were synthesized using TiCl₄ as precursor.The power conversion efficiency of DSSC based on the TiO₂ nanowires was1.67%.The specific surface area of nanowires was increased by acid etching for 3 h,and the efficiency of DSSC device was increased to 4.43%.The nanoparticles were further deposited on the etched nanowire arrays,and the power conversion efficiency of DSSC based on the composite photoanode was 4.98%.The results show that the Nb doping does not affect the crystal structure of the nanowires,but the morphology of the nanowires changes regularly with the change of Nb doping.The power conversion efficiency of 5.25%was achieved by DSSC assembled with 1 at%Nb doped nanowires etched for 4 h.?3?.The process of preparing?FAPbI₃?_0.97?MAPbBr₃?_0.03 perovskite film by two-step solution method was optimized.The perovskite solar cell based on SnO₂ planar structure obtained 18.7%power conversion efficiency under the condition of PbI₂ annealing for 1 min,which was significantly higher than that of the unannealed PbI₂ device.Mesoporous perovskite solar cells were prepared on TiO₂ nanorods arrays with different growth times?0.1 at%Nb doping?.The results show that the Nb doped perovskite photovoltaic device with a growth time of 1 h achieves the highest efficiency of 15.7%,while the efficiency of undoped devices is lower than that of Nb doped devices,which proves that Nb doped TiO₂nanorod can improve the performance of mesoporous structure perovskite solar cells.?4?.The Cu₂O thin films of cuprite phase were prepared by electrodeposition under alkaline conditions.The change of deposition time changed the grain size of Cu₂O film,but do not affect the crystal structure of Cu₂O.The change of deposition substrate affected the grain shape of Cu₂O film.A Cu₂O-TiO₂ heterojunction solar cell based on a 620 nm long Nb doped TiO₂ nanorod array obtained 0.445%power conversion efficiency.