Study On The Solar Spectrum Manipulation Based On The Quad-band Splitting And Absorbing

Now and in the future,energy problems shouldn’t be ignored.The solar radiation releases vast amounts of energy to the earth,but a small part of it can be utilized,which provides us various feasible strategies to expanding our energy sources.Thus,the topics we mainly discussed as follows.Firstly,We have briefly introduced the theories,key technologies,advantages and disadvantages of three kinds of solar energy conversion methods including photovoltaic（PV）conversion,photothermal conversion and photocatalytic hydrogen generation.What’s more,in order to address the issues in these solar conversion technologies,the hybrid photovoltaic-thermal solar system for full solar spectrum was introduced.Meanwhile,the principle of the ideal quad-band solar spectrum splitting system was discussed,which inspired us to optimize the solar spectrum optical filter for a more efficient solar energy utilization.We discussed the method and principle to realize the ideal quad-band solar spectral splitting based on one-dimensional photonic crystal theory,and analysized the key parameters for the spectrum splitting.Based on the background and methods discussed above,two kinds of solar spectrum optical filters were studied.On the one hand,we designed an efficient solar spectrum optical filter based on a cermet layer,Si/Si O₂1D photonic crystal,and top heterostructure layer.Compared with 1D photonic crystal structure,the 1D photonic crystal heterostructure with a top layer of Yttria-stabilized zirconia（YSZ）can realize a reflectance of greater than 92%in PV band and an absorptivity of greater than 50%in full solar spectrum because of the tuning of the effective impedance in multilayer films.The enhanced reflectance in PV band is due to the huge mismatching of the impedance between free space and the heterostructure filter.The top dielectric layer can also be extended to other oxides.In addition,we designed an aperiodic multilayer solar spectrum optical filter which demonstrates the characterizations of spectrum splitting with the reflectance of greater than 88%in PV band and a high absorptivity（>60%）in full solar spectrum.Compared with periodic photonic crystal,the aperiodic multilayer film has similar performance but lower costs.