Exploration Of New Photoelectric Materials For Ferroic Semiconductor With Perovskite Structure

With the development of perovskite materials in the field of solar photovoltaic technology,the demand for new solar photovoltaic materials is also increasing.Perovskite materials have been studied extensively because of their excellent optical,electrical and magnetic properties.Compared with organic-inorganic perovskite,oxide perovskite showed its advantage in chemical stability and thermal stability,meanwhile,the narrow band gap oxide perovskite materials can obtain wider range of spectral absorption.The most important thing is that oxide perovskite ferroelectric semiconductors can integrate ferroelectric bulk photovoltaic effect and semiconductor p-n junction photovoltaic effect,which might succeed in Shockley-Queisser theory PCE limit.A series of double perovskite structure ferroelectric semiconductor materials are prepared using the improved solid-state reaction electronic ceramic process and their optical,electrical and magnetic properties are studied experimentally.This work includes the following aspects.Preparation of Mn⁴⁺substituted BiFeO₃-based oxide perovskite materials:0.50BiFeO₃-0.25A₁MnO₃-0.25A₂TiO₃(A₁=Ca,Sr,Ba/A₂=Sr,Ba,Pb)series ceramics were prepared by the improved solid-state reaction electronic ceramics process.Raman scattering spectra at room temperature showed that these solid solution perovskite ceramics exhibited ferroelectricity due to spatial inversion symmetry breaking in these systems.Ultraviolet-visible-near infrared spectra test shows that they exhibit a direct band gap semiconductor of E_gin the range of 0.75-1.0 e V,electrical tests show that the resistivity in?10⁴?·m(40?)magnitude,magnetic property tests show that all the components are ferromagnetic except 0.50BiFeO₃-0.25SrMnO₃-0.25Sr TiO₃.Preparation of Co²⁺,Mg²⁺substituted BiFeO₃-based oxide perovskite materials:0.49BiFeO₃-0.26Ba TiO₃-0.25(Sr_1-xBa_x)(A_1/3Nb_2/3)O₃(A=Co,Mg)single-phase perovskite ceramics were prepared by improved solid-state reaction electronic ceramics process.Raman scattering spectra at room temperature shows that these solid solution perovskite ceramics exhibited ferroelectricity due to spatial inversion symmetry breaking in these systems.Ultraviolet-visible-near infrared spectra test shows that the E_g?0.9e V for Co²⁺substituted BiFeO₃ materials has excellent absorbing ability in Ultraviolet-visible-near infrared band.While Mg²⁺substituted BiFeO₃ materials exhibits E_g?2.0 e V.For 0.49Ba TiO₃-0.26BiFeO₃-0.25(Sr_0.6Ba_0.4)(Co_1/3Nb_2/3)O₃ perovskite,their resistivity being on the magnitude of order of?10⁴?·m.And0.1mol%MnO₂-doped 0.49BiFeO₃-0.26Ba TiO₃-0.25(Sr_0.6Ba_0.4)(Mg_1/3Nb_2/3)O₃ solid solution ceramics performance_r=460,tan?=0.03,8 k V/mm field intensity poling process at high temperature could achieve15min maintaining.Design of oxide perovskite photovoltaic cell:from the performance analysis of the material,Mn,Co substituted BiFeO₃ based solid solution perovskite ferroelectric semiconductor is suitable for the development of solar photovoltaic cells.In order to explore the method of preparing simple P-N junction,the solid solution perovskite containing A-site vacancy such as 0.50BiFeO₃-0.25A₁MnO₃-0.25A₂TiO₃(A₁=Ca,Sr,Ba/A₂=Sr,Ba,Pb)can be used as the P region,and solid solution perovskite containing oxygen vacancy such as(Bi,La)Fe O₃-Ba(B_1/2Nb_1/2)O_2.75(B=Ni²⁺,Mg²⁺,Zn²⁺)can be used as the N region of the semiconductor.In addition,Ba_0.95La_0.05Sn O₃ transparent conductive perovskite,which can be used as window material of solar photovoltaic cells,was prepared by solid-state reaction electronic ceramic process.It has a broad solar spectral transmittance in the 400-1300 nm band.