Luminescence Properties of Green-Emitting Phosphor (Ba_(1-x),Sr_x_2SiO_4∶Eu^(2+) for White LEDS

The （Ba1- x, Srx ） 2 SiO4 ： EU^2＋ green-emitting phosphors were synthesized by conventional solid-state reaction in a CO-reductive atmosphere, and their luminescent properties were investigated. The XRD data show that the Ba/Sr ratio not only affects the lattice parameters, but also influences the emission peak. The excitation spectra indicate that this phosphor can be effectively excited by UV light from 370 to 470 nm. The emission band is due to the 4f^65d^1→4f^7 transition of the Eu^2＋ ion. With an increase in x, the emission band shifts to longer wavelength and the reason was discussed. The emission spectra exhibit a satisfactory green performance under different excitation wavelength（380,398,412,420,460 nm）. （Ba1- x, Srx ） 2 SiO4 ： EU^2＋ is a promising phosphor for green white-lighting-emission diode by ultraviolet chip.

Synthesis and Luminescence Properties of Ba2 MgSi2 O7 : Eu2+ under UV Excitation

Eu2+ activated pyrosilicate phosphor were prepared under a reducing atmosphere by solid-state reaction.The crystal structure of Ba2 MgSi2 O7: Eu2+ was analyzed by XRD method.The excitation spectrum of Ba2MgSi2 O7; Eu2+ is composed of two broad bands centered at about 310 nm and 395 nm respectively.In the emission spectra, the peak wavelength is at about 507 nm under 380 nm UV excitation.It was found that the introduction of Zn2+ into Ba2MgSi2O7: Eu2+ Can effectively increase its emission intensity without changing the position of emission peak.And the Eu2 + and Ce3 + codoped pyrosilicate phosphor is the efficient bluish green phosphor under the excitation of long UV light and its emission intensity is stronger than Eu2+ doped pyrosilicate phosphor.

Research of Luminescence Properties on MO-RE2 O3 -B2 O3: Eu, Mn(M=Mg, Ca, Sr; RE=Y, La, Gd)

A series of phosphor of MO-RE2 O3-B2 O3: Eu, Mn ( M = Mg, Ca, Sr; RE = Y, La, Gd) were prepared and studied.Excitation spectra exhibited high absorption in UV region (370 ～ 400 nm).There existed two valence states for europium ions Eu2+ and Eu 3+, the broad emission band peaking at 515 nm correspond to the 5d-4f emission transition of Eu2+ , the sharp emission peaking at 590 and 610 nm correspond to the 5D0→7FJ(J = 1,2,3,4) emission transition of Eu 3 + By the introduction of Mg and Y into MO-RE2O3-B2O3: Eu, blue-green emission was restrained ultimately and red emission peaking at 610 nm was enhanced strongly, intensity and colorimetric purity of red light were both enhanced.Furthermore, Mg1-xSrxO-Y2O3-B2O3: Eu was also researched, the introduction of Sr into MgO-Y2O3-B2O3:Eu gives rise to a shift to longer wavelengths of the position of the excitation peak, and the emission spectra varies with the increasing of x simultaneously.

Improvement in efficiency of solar cell by removing Cu2-xSe from CIGS film surface

CIGS thin films are deposited by sputtering and selenization, The synthesis of semiconducting polycrystalline thin films and characteristics of devices based on the CIGS absorbing layers are investigated. Their microstructures are characterized by x-ray diffraction and Raman spectroscopy, The results reveal that there exist metallic Cu2-xSe compounds in CIGS film surfaces and the compounds are thought to be responsible for the degradation of the open circuit voltage of solar cells. The optimization of selenization temperature profile and copper content in the precursor surfaces is studied, concluding that the conversion efficiency may be improved by removing metallic Cu2-xSe compounds from the surfaces of CIGS thin films.