TiO2微粒对远程荧光粉膜及白光发光二极管器件光色性能的影响

利用热压法将TiO₂微粒掺入至YAG:Ce荧光粉和硅树脂中制备出远程荧光粉膜并封装成白光发光二极管(LED)器件, 通过荧光粉相对亮度仪、双积分球测试系统和可见光光谱分析系统对样品的光色性能及机理进行了研究. 结果表明: TiO₂的散射效应能够显著提高蓝光的利用率和黄光的透射强度, 白光LED器件的光通量在TiO₂浓度为0.966 g/cm³ 时达到最高值415.28 lm(@300 mA, 9.3 V), 提高了8.15%, 相关色温从冷白6900 K逐渐变化至暖白3832 K. TiO₂的掺入不仅提高了远程荧光粉膜的发射强度和白光LED器件的光通量, 同时能调控其相关色温.

Investigation of photo-chromic properties of remote phosphor film and white light emitting diode mixed with TiO2 particles

Based on the hot pressing method, the remote phosphor films are prepared by adding TiO₂ particles into YAG:Ce and silicon binder, and then they are packaged into white light emitting diode (WLED) device with chip on board (COB) blue light source. The photo-chromic properties and mechanism are studied and calculated. Based on Mie theory and Henyey-Greenstein function, forward scattering is the main light scattering form of YAG:Ce phosphor powder, while the forward scattering intensity is close to the back scattering intensity of TiO₂ particles. The emission spectral intensity and relative luminance of remote phosphor film change with increasing the concentration of TiO₂ particles, and the optimum concentration is 0.966 g/cm³. Forward transmission intensity and back reflection intensity are calculated and analyzed, when the concentration of TiO₂ is low, the forward transmission intensity of blue light is stronger than that of yellow light and the main transmission form is forward transmission, while the forward and backward intensity of yellow light are similar because of isotropy. With increasing the concentration of TiO₂, the forward intensity of blue light gradually decreases, and the transmission intensity is lower than that of yellow light. The forward and backward intensity of yellow light reach their maxima when the TiO₂ concentration is 0.966 g/cm³. The main reason for this phenomenon is that the increasing of the utilization ratio between blue light and transmission of yellow light is affected by the strong scattering ability of TiO₂. Finally the WLEDs are packaged by remote phosphor films and COB blue light source, the luminous flux of WLED reaches 415.28 lm (at 300 mA and 9.3 V) at a concentration of 0.966 g/cm³, which is increased by 8.15% compared with the concentration in the case of no TiO₂ mixing. Besides, the correlated color temperature changes from cool white 6900 K to warm white 3832 K gradually. Consequently, the adding of TiO₂ particles can not only improve the emission intensity of remote phosphor film and the luminous flux of WLED, but also regulate the correlated color temperature.