| The conversion of solar energy into electricity is one of the renewable energy technologies vigorously developed by human beings.With the emerging development of the third-generation solar cells,dye-sensitized solar cells(DSSC)have been extensively studied these days.Currently,DSSC has achieved certification efficiency of up to 11.9%.The rapid development of these solar cells is of great significance for further application of photovoltaic technology.Although these devices with high efficiency have been studied rapidly,many problems still need to be solved for the practical application.For example,the liquid electrolyte of DSSC is easy to leak,and the long-term stability of devices cannot be guaranteed.Large interfacial resistance between solid electrolyte and electrodes on both sides limits device performance.As for the above concerned issues,we have designed and synthesized a series of novel ionic liquids for high-performance DSSCs.The detailed research contents are mainly divided into the following parts:1.Alkyl nitrile pyrrolidine optimized solid electrolyte for high-performance solid-state DSSC.A series of pyrrolidinium cations bearing alkyl nitrile moieties have been designed to synthesize functional solid electrolyte with high purity and yield.We have systematically studied the influence of the anion structure and methylene chain length of the alkyl nitrile moieties on the thermal properties of functional ionic liquids.With respect to the anion structure,the thermal stability is in the order of I-<PF6-<TFSI-.Meanwhile,increasing the methylene chain length from 1C to 3C of pyrrolidinium cations bearing alkyl nitrile moieties can increase the melting points of the solid ionic crystals.Investigation shows some of the ionic liquids have obvious plastic crystal phase behavior with rotational disorder and activated vacancies/defects,which can offer a solid bulk matrix for doping 1-propyl-3-methylimidazolium iodine(PMII),LiI and I2 to prepare plastic crystal electrolytes with high melting points and conductivities.In addition,the resulting solid-state dyesensitized solar cell(ssDSSC)exhibits a power conversion efficiency(PCE)of 5.22%under the simulated air mass 1.5 solar spectrum illumination at 100 mW cm-2.These results offer us a feasible method to explore new organic plastic crystals and electrolytes for high temperature ssDSSCs.2.Novel three-armed imidazolium phenoxy ionic liquid(TIPIL)inhibiting the crystallization of electrolyte for efficienct ssDSSC.TIPIL has been successfully designed,synthesized to inhibit the crystallization of electrode in ssDSSC.We have systematiclly studied the thermal property,amorphous feature,and ionic conductivity of TIPIL.It was found that 1-Ethyl-3-methylimidazoliumiodide(EMII),a typical ionic conductor,could be effectively inhibited from crystallization by TIPIL.Compared with the reference device,the DSSC containing TIPIL showed improved photovoltaic conversion efficiency up to 5.37%as well as excellent long-term stability.This study provides a feasible method to explore new crystal growth inhibitors for ssDSSCs.3.A kind of high viscous light-scattering crystal growth inhibitors(LCGIs)enhancing the light-harvesting efficiency of photoanode in ssDSSC.The thermal,electrical and light-scattering properties of LCGIs-based solid-state electrolytes are investigated.Addition of the high viscous LCGI to ionic crystal EMII could effectively prevent EMII from recrystallization and enhance the light-harvesting efficiency of the TiO2 photoanode,resulting in larger photocurrent for ssDSSC.The resulting ssDSSCs show high efficiency and they remain almost over 95%of its initial conversion efficiency after the 50 days' aging test.It is noting that LCGIs-based electrolytes can act as conventional TiO2 light-scattering layers without sacrificing device performances,providing a new method to explore new solid-state electrolytes and much thinner ssDSSCs.4.Room temperature nickel oxide nanoarray for efficient flexible solar cells.We for the first time grow NiOx nanopillar arrays on flexible substrates at room temperature employing glancing angle deposition.Experiments demonstrate that the nanopillar array structure not only improves carrier transport efficiency,but also acts as a light trapping architecture,increasing the absorption of light by perovskite,thus improving device performance.Compared with the control device fabricating on a traditional planar structure,it is shown that the power conversion efficiency could be improved by 21%,and reaches up to 20.05%with NiOx nanopillar arrays on rigid substrates.More interestingly,it is demonstrated that nanopillar arrays can be a great help in relaxing stress and strain upon device bending,which suppresses crack nucleation in different layers of PSCs.As a result,the performance of NiOx nanopillar arrays based flexible device is as high as 17.23%and remains more than 80%of the initial value even after 500 mechanical bending cycles,which is outstandingly better than that of control devices in the same condition. |
PDF Full Text Request