Application Of YAG:Ce Phosphors In Crystalline Silicon Solar Cells

Solar energy has attracted more and more attention because it is inexhaustible,clean,safe and renewable.Improving the performance of the solar cells is always an active research field.Among the factors that limit the performance of crystalline silicon solar cells,the poor response in UV/blue range play an important role.When the crystalline silicon solar cells absorb one short wavelength photon whose energy is higher than the band gap?1.12eV?,only 1.12eV is needed to generate one pair of electron-hole,other energy will be transferred into carriers thermalization which will decrease the efficiency of the solar cells.Besides that,the crystalline silicon solar cells has the high surface reflection and short penetration depth in short wavelength range.That makes it difficult to generate more electron-hole pairs inside the cells.One of the methods to solve the problem is to introduce down-shifting materials which can convert short wavelength photons into longer wavelength photons.YAG:Ce phosphors are a kind of rare earth luminescent materials and have widely been used in the LED industry.In the experiment,high temperature solid reaction method was selected to make YAG:Ce phosphors.Luminescence characteristics of YAG:Ce phosphors showed that the YAG:Ce phosphors can convert the shorter photons below 480 nm to longer photos above 500 nm.By coating YAG:Ce phosphors on the surface of the monocrystalline silicon solar cells through screen printing method,packaging the solar cells with EVA and quartz glass,it was found that the conversion efficiency increases from 17.24%to 18.13%,the relative growth of 5.16%.This can be attributed to the down-shifting effect of YAG:Ce and the reduction of the reflection in the short wavelength range.Besides YAG:Ce phosphors,Eu-doped red phosphors(Sr₂Si₅N₈:Eu²⁺)which have high excitation efficiency in short wavelength range were also investigated.They were applied on GaInP solar cells of GaInP/GaAs/Ge triple junction solar cells.The results showed that the external quantum efficiency of GaInP solar cells had been improved in the whole visible band.