The interface adhesion of CaAlSiN&lt;sub&gt;3&lt;/sub&gt;: Eu&lt;sup&gt;2+&lt;/sup&gt; phosphor/silicone used in light-emitting diode packaging: A first principles study

Cui, Z.; Fan, J.; van Ginkel, H.J.; Fan, Xuejun; Zhang, Kouchi

doi:10.1016/j.apsusc.2020.145251

The interface adhesion of CaAlSiN₃

Title

The interface adhesion of CaAlSiN₃: Eu²⁺ phosphor/silicone used in light-emitting diode packaging: A first principles study

Author

Cui, Z. (TU Delft Electronic Components, Technology and Materials)
Fan, J. (TU Delft Electronic Components, Technology and Materials; Hohai University)
van Ginkel, H.J. (TU Delft Electronic Components, Technology and Materials)
Fan, Xuejun (Lamar University)
Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)

Date

2020-04-30

Abstract

The CaAlSiN₃:Eu²⁺ red phosphor and its silicone/phosphor composite are very promising materials used in the high color rendering white light-emitting diode (LED) packaging. However, the reliabilities of CaAlSiN₃:Eu²⁺ and its composite are still being challenged by phosphor hydrolysis at high humidity application condition. A fundamental understanding of the interface adhesion between silicone and CaAlSiN₃:Eu²⁺ is significant for the developments and applications of this material. In this work, the mechanical properties of silicone/pristine CaAlSiN₃:Eu²⁺ and silicone/hydrolyzed CaAlSiN₃:Eu²⁺ composites are experimentally measured and compared firstly, in which both the tensile strength and Young's modulus of composite are increased after the hydrolysis reaction. Then, the first principles Density Functional Theory (DFT) calculations are used to investigate the adhesion behaviors of the silicone molecular on both the pristine and the hydrolyzed CaAlSiN₃[0 1 0] at atomic level. The results show that: (1) The silicone molecular is weakly adsorbed on the pristine CaAlSiN₃[0 1 0] via Van der Waals (vdW) interactions, while silicone molecular is much stronger absorbed on the hydrolyzed CaAlSiN₃[0 1 0] due to the formation of hydrogen bonding at the interface; (2) The transient state calculations indicate that the sliding energy barrier of silicone on the hydrolyzed CaAlSiN₃[0 1 0] is higher than that on the pristine one, as the increased adsorption energy and surface roughness. Generally, the findings in this paper can guide the phosphor selection, storage and process in LED packaging, and also assist in improving the reliability design of LED package used in high moisture condition.