Preparation And Performance Of PMMA/SrAl₂O₄ Composite Films For Luminescent Solar Concentrator

The solar photovoltaic power generation has drawn great attention.However,high costs have limited their application in market.Photovoltaic concentrator system is one of effective ways to reduce the cost of solar power,in which use relatively cheaper solar concentrators to substitute for the expensive solar cells plate.However,conventional solar concentrators need a set of special system with a cooling system to track the sun,which increase the cost.Luminescent solar concentrator can collect the sunlight without solar tracking system and cooling system.However, it is difficult to work when there isn’t sufficient sunlight due to the change of weather and climate. Therefore,for continuing work of solar photovoltaic power generation,doping nanosized strontium aluminate long afterglow phosphors into PMMA（optical waveguide） to prepare composite material,in which the phosphors absorbed and stored the solar energy during the day, then re-released the energy at night.Based on this idea,in the dissertation,the nanosized strontium aluminate long afterglow phosphors/PMMA composites were prepared and the main contents are as following.1.SrAl₂O₄:Eu²⁺,Dy³⁺nanometer phosphors were prepared by sol-gel（phosphor A） and high temperature solid state annealing methods（phosphor B）.The results show that the size of phosphors A is about 60nm-120nm,which is smaller than that of phosphors B.The excitation state absorption spectrum of phosphor A is a continuous broadband spectrum between 300nm and 500nm.The excitation peak of phosphor A moves slightly towards long wave length compared to phosphor B.The wavelength range of Emission spectrum is a broadband spectrum in the range of 400-650 nm,and the peak is at around 520nm due to the smaller size of phosphor A to result in more Eu²⁺ ions on particle surface compared with phosphor B.2.PMMA/SrAl₂O₄ composites were prepared by in-situ polymerization and solution blending method.SEM photographs showed that PMMA/SrAl₂O₄ composites obtained by in-situ polymerization exhibits more uniformly dispersion compared that from solution blending method. The uniformly dispersion mechanism was investigated and it is found that dipole-dipole interaction between MMA monomer and inorganic SrAl₂O₄ yields strong absorbance of MMA on SrAl₂O₄ nanoparticle’s surface,then was in-situ polymerized.The generated polymer worked as a barrier and can effectively prevent the aggregation of nanoparticles which result in uniformly dispersion.Simultaneously,it is found that the resulted composites possess enhanced thermal stability.The more the added amount of SrAl₂O₄ phosphor,the higher the thermal stability of the composites,which may be assigned to two reasons:high thermal stable nanoparticles to prevent the conduction of heat and nanoparticles to reduce the mobility of free radicals or to annihilate part radicals to restrain the radicals initiating more molecular chain to break.