Enhancement of PLED lifetime using thin film passivation with amorphous Mg‐Zn‐F

Abstract

In this study, a new thin films passivation technique using Zn with high electronegativity and MgF₂, a fluorine material with better optical transmittance than the sealing film materials that have thus far been reported was proposed. Targets with various ratios of MgF₂ to Zn (5:5, 4:6 and 3:7) were fabricated to control the amount of Zn in the passivation films. The Mg‐Zn‐F films were deposited onto the substrates and Zn was located in the gap between the lattices of MgF₂ without chemical metathesis in the Mg‐Zn‐F films. The thickness and optical transmittance of the deposited passivation films were approximately 200 nm and 80%, respectively. It was confirmed via electron dispersive spectroscopy (EDS) analysis that the Zn content of the film that was sputtered using a 4:6 ratio target was 9.84 wt%. The Zn contents of the films made from the 5:5 and 3:7 ratio targets were 2.07 and 5.01 wt%, respectively. The water vapor transmission rate (WVTR) was determined to be 38°C, RH 90–100%. The WVTR of the Mg‐Zn‐F film that was deposited with a 4:6 ratio target nearly reached the limit of the equipment, 1×10^‐3 g/m²•day. As the Zn portion increased, the packing density also increased, and it was found that the passivation films effectively prevented the permeation by either oxygen or water vapor. To measure the characteristics of gas barrier, the film was applied to the emitting device to evaluate their lifetime. The lifetime of the applied device with passivation was increased to 25 times that of the PLED device, which was non‐passivated.

Keywords:

• PLED
• passivation
• fluoride
• WVTR

Notes

Student member, KIDS

School of Electrical Engineering and Computer Science, Kyungpook National University, Daegu, South Korea

Center for Functional Devices Fusion Platform, Kyungpook National University, Daegu, South Korea

Department of Sensor and Display Engineering, Kyungpook National University, Daegu, South Korea

Member, KIDS

Department of Physics, Kyungpook National University, Daegu, South Korea

School of Electronic Information and Communication Engineering, Kyungil University, Gyeongsan‐si, South Korea