Executive Summary : | Objective: To develop novel direct white light luminescent material and fabricate WLEDs, where these materials can evade color reabsorption and overcome the pressing issues among phosphors properties and improve the color rendering index and luminous efficiency Summary: White light generation approached to the next level of challenge in solid-state technology. The major technological efforts have been dedicated for achieving full potential of white LEDs (W-LEDs) with good luminous efficacy, high chromatic stability, high color-rending properties, and lowcost competitiveness with fluorescent lamps, which rely critically on the phosphor properties. Currently, few methods are used to produce W-LEDs in which GaN blue diode coated with YAG:Ce3+ yellow phosphor layer is of more interest. Generation of white light by combining tri-color (red, green and blue (RGB)) phosphors with a near UV diode also exists. However, both the methods are having many drawbacks such as: low color rendering index (CRI), poor reproducibility of color, less thermal stability at high operating temperatures (Y. Wang et.al. 2015). Alternatively, white light emission can also be produced by co-doping ions based on the energy transfer mechanism. Moreover, single-molecule luminescent materials can emit white light without doping ions by controlling the concentration of defects. The design of single material that can emit white light will enable to surpass shortcoming that includescritical issues of color balance, thermal stability and inherent loss mechanisms of photon Stokes-shifting between optical excitation and sharp emission wavelengths. The underlying idea of this proposal is to develop novel direct white light luminescent material and fabricate WLEDs, where these materials can evade color reabsorption and overcome the pressing issues among phosphors properties and improve the color rendering index and luminous efficiency. In this proposed project we would also like to extend the study on one of unusual single material, discovered in our lab IMMT, that exhibit highly intense broad emission over the entire visible spectral range (400-800 nm) and thus can be utilized for designing white light emission devices. The patent in India and US has already been filed for this new material developed in our lab at IMMT that exhibit unusual white light emission. |
