Preparation Of Transition Metal Compounds And Their Application In Novel Solar Cells

With the development of human society,people's awareness of environmental protection is gradually developed.But the environmental pollution caused by fossil fuels is becoming more and more serious.And as a kind of non-renewable energy,fossil fuels also face the situation of exhaustion.Therefore,developing sustainable clean energy is the only way for future development.Solar energy is a clean energy and has advantages of resourceful,clean and safe.Moreover,the exploitation of solar energy is versatile and isn't subject to geographical conditions.So solar energy is a ideal green energy.Dye-sensitized solar cell?DSSC?is a typical representative of the third-generation solar cells and it has attracted world-wide attention due to its low cost,easy fabrication process and high efficiency.Later on,with the development of DSSC,people used metal organic halide to instead traditional dye to prepare a new kind of solar cell,perovskite solar cell?PSC?.Compared with DSSC,its efficiency has been greatly improved and its highest efficiency has come to 22.7%.The PSC is thought to be a new milestone in the filed of solar cells,providing new opportunities for the development of third-generation solar cells,but it also faces new challenges.Although the manufacturing costs of DSSC and PSC are less than traditional silicon-based solar cells,but there are still many aspects restricts their commercial.For one,the most commonly used counter electrode material of DSSC is Pt.Pt is precious metal.For another,the long-term stability of DSSC and PSC device is opaque.Based on the above aspects,on the basis of level,structure and interface matches,this paper focuses on the improvement of electrode materials of DSSC and PSC.The main research contents of this paper are summarized as follows:?1?a well redispersed Ni_0.85Se was prepared by solvent thermal method and Ni_0.85Se/FTO counter electrode was prepared by spin-coating Ni_0.85Se dispersion.By optimizing the thickness of Ni_0.85Se thin film with different spin-coating speed,a Ni_0.85Se/FTO counter electrode for DSSC with high catalytic performance was successfully prepared.The power conversion efficiency?PCE?comes to 10.19%,which outperforms Pt.?2?CoTe nanowires were synthesized by hydrothermal method and CoTe/FTO counter electrode was prepared by spin-coating CoTe nanowires dispersion.In addition,RGO was introduced to the system to further increase the photoelectric performance of DSSC.RGO has excellent electrical conductivity and owns large specific surface which is in favour of electron transport performance and catalytic property.Finally,the DSSC based on CoTe/FTO obtains a PCE of 9.18%,which is better than that of Pt.?3?a uniform CoSe₂ nanosheet film was in situ grown on FTO by electrochemical deposition method.The nanosheet structure helps to increase catalytic activity point,resulting CoSe₂/FTO counter electrode get a PCE of 10.17%.?4?in order to improve the stability of the PSC,the TiO₂ electron transport layer was treated by an In?NO3?3 solution in isopropanol.And by optimizing the concentration of In?NO₃?₃ solution,the PCE of PSC increases from 16.71%to18.93%.And the stability of the PSC was also improved.?5?the down-conversion NaYF₄:Eu³⁺was prepared by hydrothermal method.Spin-coating NaYF₄:Eu³⁺on the back of FTO substrate can transform part of ultraviolet light to red light,increasing the light absorption of perovskite materials.Furthermore,it can reduce the influence of ultraviolet light on Ti O₂,thus the PCE of PSC increases from 16.99%to 19.99%.