Red color Sr_(2)NaMg_(2)V_(3)O_(12):Eu^(3+)phosphor with high thermal stability for w-LEDs

Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphors with uniform particle size/morphology and good dispersion can be synthesized via solid state reaction.Under the optimum excitation wavelength of ~340 nm,the Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphor displays the broad emission band at ~500 nm(blue-green emission,^(3)T_(1,2)→^(1)A_(1) transition of[VO_(4)]^(3-))and sharp emission peak at~610 nm(red emission,^(5)D_(0)→^(7)F_(2) transition of Eu^(3+)),respectively.With the Eu^(3+)content increasing,the emission intensity of[VO_(4)]^(3-)decreases gradually while the emission intensity of Eu^(3+)increases,which is ascribed to the energy transfer from[VO_(4)]^(3-)to Eu^(3+)ions.The decay time of[VO_(4)]^(3-)(-500 nm)increases gradually with the Eu^(3+)content increasing.The energy transfer efficiency and mechanism of[VO_(4)]^(3-)→Eu^(3+)ions were analyzed,respectively.The emission color of Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphor was regulated from green to red via altering the Eu^(3+)ions concentration.It is delightful for us that the white color emission can be just achieved when the Eu^(3+)content is 5 at%(x=0.05),and the w-LED can be assembled.By studying the luminescence temperature dependence and activation energy of Sr_(2)NaMg_(2)V_3O_(12):xEu phosphor,it is shown that the phosphor has good thermal stability.The Sr_(2)NaMg_(2)V_3O_(12):xEu powder is expected to be a new type of phosphor widely used in light and display areas.

Phosphor-aluminosilicate CsPbX_(3) perovskite fluorescent glass with low formation temperature for photoluminescence display applications

All-inorganic perovskites are rapidly emerging as novel optoelectronic functional materials owing to their flu-orescence properties.However,the stability of these materials has always been the biggest challenge for their applications in photoelectric devices.Therefore,this study focuses on developing phosphor-aluminosilicate-based CsPbX_(3)(X=Cl,Br,and I)glass with a low reaction temperature by adding CsCO_(3),PbX_(2),and NaX to the raw materials in order to improve the stabilities.The glass network intermediates of SiO_(2) and Al_(2)O_(3) doping in the raw material enhanced the stability of the pure phosphate glass network structure and devitrification while decreas-ing the melting temperature.Full chromatographic CsPbX 3 quantum dots(QDs)encapsulated in phosphate-based glass were found to increase the fluorescence properties and quantum efficiency(>59%).Notably,the high water stability of CsPbX_(3) QDs glasses,with the maintenance of 90% luminous intensity,emerged when soaked in water.In addition,the excellent thermal stability and anti-ion exchange properties of the CsPbX_(3) QDs glasses were re-vealed.Benefiting from the above,multicolor light-emitting diode(LED)devices were assembled with a mixture of phosphors of CsPbX_(3) QDs glasses and commercial red-emission K 2 SiF 6:Mn 4+phosphor spread on an InGaN chip,demonstrating bright light with superior luminous properties.Phosphor-aluminosilicate-based CsPbX_(3) QDs glass with high stability and low formation temperature would provide new methods for applications in lighting and displays.

Effect of active layer deposition temperature on the performance of sputtered amorphous In–Ga–Zn–O thin film transistors

The effect of active layer deposition temperature on the electrical performance of amorphous InGaZnO （a-IGZO） thin film transistors （TFTs） is investigated. With increasing annealing temperature, TFT performance is firstly improved and then degraded generally. Here TFTs with best performance defined as ＂optimized-annealed＂ are selected to study the effect of active layer deposition temperature. The field effect mobility reaches maximum at deposition temperature of 150℃ while the room-temperature fabricated device shows the best subthreshold swing and off-current. From Hall measurement results, the carrier concentration is much higher for intentional heated a-IGZO films, which may account for the high off-current in the corresponding TFT devices. XPS characterization results also reveal that deposition temperature affects the atomic ratio and Ols spectra apparently. Importantly, the variation of field effect mobility of a-IGZO TFTs with deposition temperature does not coincide with the tendencies in Hall mobility of a-IGZO thin films, Based on the further analysis of the experimental results on a-IGZO thin films and the corresponding TFT devices, the trap states at front channel interface rather than IGZO bulk layer properties may be mainly responsible for the variations of field effect mobility and subthreshold swing with IGZO deposition temperature.

The influence of RF power on the electrical properties of sputtered amorphous InGa-Zn-O thin films and devices

The influence of radio frequency（RF） power on the properties of magnetron sputtered amorphous indium gallium zinc oxide（a-IGZO） thin films and the related thin-film transistor（TFT） devices is investigated comprehensively.A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined.The results prove that the deposition rate sensitively depends on RF power.In addition,the carrier concentration increases from 0.91 x 1019 to 2.15 x 1019 cm-3 with the RF power rising from 40 to 80 W,which may account for the corresponding decrease in the resistivity of the a-IGZO thin films.No evident impacts of RF power are observed on the surface roughness,crystalline nature and stoichiometry of the a-IGZO samples.On the other hand,optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W,as is supposed to result from the carrierinduced band-filling effect.The rise in RF power can also affect the performance of a-IGZO TFTs,in particular by increasing the field-effect mobility clearly,which is assumed to be due to the alteration of the extended states in a-IGZO thin films.