Polymer-embedded AC-driven Light-emitting Diode (LED) Assembly

Abstract

The traditional framework of LED assembly can only work with direct current(DC) source, and requires soldering/wire bonding, limiting the flexibility and further improvement of display resolution. In this thesis, an innovative small-size AC-driven LED assembly has been successfully developed, in which LEDs get their power through insulating dielectric layers without wire bonding when using high-frequency AC source. This novel package method of an AC powered flexible dual-LED unit is built up with two reverse-parallel-connected LED chip, namely dual-LEDs. The dual-LEDs preparation process is involved with the surface and interface modification, dielectric composites and combined transparent electrode layer processing. The key parameters of preparing the polymer-embedded LED platelet are obtained and the properties of combined transparent electrodes of Indium Tin Oxide(ITO)/silver nanowires(AgNWs) have been investigated. The luminous properties of the AC-driven assembly are explicitly evaluated based on the Sawyer-Tower method and the luminous intensity and luminous efficiency in variation of input AC voltage are presented. The package shows a good flexibility and is much smaller in size compared with traditional LED package, as well as eliminates the need of wire-bonding to be powered on. The method of assembly is very promising in the future low cost printed assembly of large numbers of dual LED platelets in a sheet or strip.