利用複合式結構與布拉格反射鏡製作高效率高品質白光發光二極體

Abstract

摘 要 近年來，白光發光二極體已成為人類社會中相當重要的光源，並且有足夠的潛力取代傳統光源，為使此光源更加廣泛運用，高效率與高均勻性的白光光源成為相當重要的指標。於本論文中，將分為兩個主題進行探討，首先我們將利用複合式結構製作高效率與高色品質的暖白光發光二極體，接者，利用布拉格反射鏡以解決高效率冷白光發光二極體色均勻度的問題。 首先，利用複合式結構製作暖白光發光二極體，以達到高效率與高色品質的目標，相較於點膠方式能達到更高效率的原因為複合式結構設計有漸變折射率與減少再吸收現象之功能，此外，透過藍光、黃光與紅光之均勻混光，使色均勻度有明顯的表現。因此，此複合式結構設計具有高效率且高色品質之優點，適合做為未來室內照明元件。 接者，我們在分離式封裝結構中法利用布拉格反射鏡改善冷白光發光二極體的色均勻度，利用此結構可有效提高10%之發光效率，並且藉由布拉格反射鏡結構之變角度反射率之特點，成功改善變角度色溫的問題，相較於傳統結構可從原始1758K降至280K。利用布拉格反射鏡結合分離式發光二極體封裝結構具有潛力運用於下世代發光元件。

Abstract White light-emitting diodes (LEDs) have been regarded as the most important next-generation light source and have the great potential to replace the traditional lighting. To meet the practical need in the solid state lighting, the characteristic of high luminous efficiency and uniform angular-dependent correlated color temperature (CCT) become two major challenges for white LEDs. In thesis, we divided into two parts. First of all, we propose the hybrid structure with high lumen efficiency and color uniformity in warm white LED. After that, the angular CCT deviation is reduced to 280K by capping the DBR structure is demonstrated in cool white light emitting diode. In first section, we propose the hybrid structure with high lumen efficiency and uniform angular-dependent correlated color temperature (CCT) for warm white LED.The experimental results indicate that the hybrid structure yielded higher lumen efficiency than conventional phosphor structure because of the suitable refractive index difference from the coating layer to the dispense layer. Moreover, the CCT deviations value of the hybrid phosphor structure could be reduced to and 25K in range of -70 to 70 degrees. This is attributed to the uniform color mixing of the blue, yellow and red band in the hybrid phosphor structure. As the result, the technology of the hybrid structure with high lumen efficiency and uniform angular-dependent CCT is suitable to use in the general lighting market.

In second section, we demonstrate the application of DBR structure into the remote phosphor structure improves the angular correlated color temperature (CCT) deviation in white light-emitting diodes (WLEDs). In the experiment, the LED device with DBR structureyieldedahigher luminous efficiency than a conventional structure. This result indicated that the CCT deviation can be improved from 1758K to 280K in a range of -70 to 70 degree and the brightness is also upgrading, the luminous flux increases more than 10% due to the enhancement of the light extraction of the blue light. Moreover, the reflectance of the different DBR structure between the wavelength and the view anglewereverified in this research. As the result, this LED device with DBR structure shows the great potential to use as the next generation lighting source.