Regulation On Photovoltaic Properties Of Hybrid Perovskite Nanowire Arrays With Core-shell Structures

As an indispensable and important energy,oil is closely related to human survival and development.Its distribution is mostly located in shallow sea,Gobi and desert,which brings great difficulties to the power supply in oil exploration and exploitation.At present,portable small equipment powered by battery is mostly used for operation,but the service life of battery is low and it pollutes the environment.Perovskite solar cells（PSCs）have attracted much attention because of their excellent photoelectric performances and great development potential.They have low cost and low pollution,and can effectively replace batteries in petroleum operations.The conversion of the film structure of the battery to the nanowire structure can improve the utilization of light using its antireflection,light trapping and other functions,and provide direct transport channels for carriers,which is one of the effective means to improve the performance of the battery.In solar cells,a transport layer is usually needed to enhance the transport capacity of carriers.Based on this,in this paper it is supposed that the electron transport layer is prepared as nanowires,and then coated with the light absorption layer to form the core-shell nanowire structure,so as to improve the performance of PSCs by using its high light absorption performance and the interface synergy between core and shell.However,there are often many interface defects and illogicalities of energy level matching between the electron transport layer and the light absorption layer,which inhibit the carrier transport process and is not conducive to the improvement of the performance of PSCs.Therefore,this paper focuses on the interfaces between electron transport layer and perovskite of core-shell nanowire array perovskite solar cells.The main research contents and conclusions are as follows:（1）Combined with simulation and experimental verification,the effect of electron transport materials（TiO₂,Zn O,WO₃）on the performances of core-shell nanowire array perovskite solar cells was studied.Firstly,the battery device model is established in lumerical device software,and the influence of electron transport materials on the optical performance of the battery is studied by FDTD simulation system.The results show that the battery with TiO₂as electron transport layer has better light absorption performance.Then,the core-shell nanowire array solar cells with TiO₂,Zn O and WO₃ as the core layer and MAPb I₃ as the shell layer were prepared by hydrothermal method and spin coating method respectively.The results show that the photoelectric conversion efficiency of the device with TiO₂ as the transmission layer is the highest（5.93%）,which is due to its strong light absorption energy,more matching between the energy level structures of the transmission layer and perovskite,high electron transport capacity,low defect state density and low carrier recombination rate.（2）The green antisolvent（toluene）with low cost and less pollution was introduced to modify the perovskite MAPb I₃ layer.Adjusting the preheating temperature（25°C,50°C,75°C）and the addition amount of toluene（30μL,60μL,90μL）,its effect on the performanceof TiO₂@MAPb I₃ core-shell nanowire arrays is explored.The results show that increasing the preheating temperature and the addition of toluene can further increase the crystallinity of perovskite,optimize the perovskite interface,reduce defect recombination,enhance the electron transmission capacity,and gradually improve the photoelectric conversion efficiency.When the preheating temperature of toluene is 75°C,the photoelectric conversion efficiency is 7.42%.When the addition of toluene is 90μL,the photoelectric conversion efficiency is 7.97%.（3）Introducing modifiers（TiCl₄）to modify the interface between the electron transport layer TiO₂ and the perovskite layer MAPb I₃ to reduce surface defects caused by interfacial contact.By changing the TiCl₄ concentration（0.05 mol/L,0.1 mol/L,0.2 mol/L）and the modification time（1 h,2 h,3 h）,the effects of different process parameters on the performances of TiO₂@MAPb I₃ nanowire arrays were explored.The results show that with the increase of TiCl₄ concentration,the crystallinity of TiO₂,the size of perovskite encapsulation,the light absorption capacity and photoelectric conversion efficiency increase,and the carrier recombination and defect state density decrease.When the TiCl₄ concentration is 0.2 mol/L,the photoelectric conversion efficiency is the highest（7.2%）.With the increase of TiCl₄modification time,the crystallinity of the device further increased,and the light absorption capacity and the photoelectric conversion efficiency were improved.When the TiCl₄modification time is 3 h,the photoelectric conversion efficiency is the highest（7.73%）.The work of this paper shows that the core-shell nanowire array has better photovoltaic performance,and higher photoelectric conversion efficiency can be obtained by improving the interface,which provides some references for the research and development of perovskite solar cells and other photovoltaic devices.