Abstract
The mismatch of refractive index (RI) between light emitting diode (LED) chips and packaging resins severely lowers the lighting emitting efficacy of LED. The RI can be enhanced by the introduction of high RI nanoparticles but meanwhile it is a great challenge to maintain the high transparency for resins due to the agglomeration of nanoparticles. In this work, a facile strategy is proposed to fabricate silicone nanocomposites with a high transparency (>88%, less than 2% decrease relative to pure silicone resin), largely enhanced RI (an increase from 1.42 to 1.60) and improved thermal stability (73 °C increase in weight loss of 50%). Specifically, the ultra-fine monodispersed TiO2/silicone composites are prepared by direct solvent mixing of 1 wt% surface modified TiO2 nanoparticles (S-TiO2) into the silicone resin, in which S-TiO2 are prepared by direct introduction of titanate coupling agent in the process of TiO2 growth to induce the formation of protective layer on the surfaces of TiO2 nanoparticles. This methodology demonstrated is simple, cost-effective and versatile for the massive fabrication of highly transparent LED packaging materials with greatly enhanced refractive index and meanwhile enhanced thermal stability.
Highlights
Light emitting diodes (LEDs) have drawn considerable interests in the last several decades due to their high lighting efficiency and lighting wavelength tunability[1,2,3,4]
The TiO2 nanoparticles synthesized via sol-gel approach were introduced into silicone resin/acetic ether solution under ultrasonic treatment, forming a uniform suspension
The only difference of the preparation procedure between surface modified ultra-fine TiO2 (S-TiO2)/silicone nanocomposite and un-treated TiO2/silicone nanocomposite is the introduction of titanate coupling agent, which endows TiO2 nanoparticles with protective layers on their surface
Summary
Light emitting diodes (LEDs) have drawn considerable interests in the last several decades due to their high lighting efficiency and lighting wavelength tunability[1,2,3,4]. Various methods have been developed to improve the dispersion of TiO2 nanoparticles in silicone resin, likewise, surface modification of TiO2 nanoparticle in the process of sol-gel[19,20,21], modification of silicone resin and etc.[22, 23] These approaches usually involve toxic agents and complicated processing procedures of synthesis, purification, mixing of TiO2 nanoparticles[24], and so on. A highly transparent TiO2/silicone nanocomposite with a high RI and high thermal stability can be obtained by directly mixing the ultra-fine S-TiO2 nanoparticles with the silicone resin. To evaluate their potential as LED packaging material, the transmittance, RI and thermal stability of the as-prepared silicone nanocomposite are examined. Several types of TiO2 nanoparticles without the introduction of coupling agent and the corresponding composites are prepared and compared with the surface modified S-TiO2 case
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
