Thin film encapsulation for quantum dot light-emitting diodes using a-SiNx:H/SiOxNy/hybrid SiOx barriers

A facile thin film encapsulation (TFE) method having a triple-layered structure of a-SiN_x:H/SiO_xN_y/hybrid SiO_x (ASH) on QD-LEDs was performed utilizing both reproducible plasma-enhanced chemical vapor deposition (PECVD) and simple dip-coating processes without adopting atomic layer deposition (ALD). The ASH films fabricated on a polyethylene terephthalate (PET) substrate show a high average transmittance of 88.80% in the spectral range of 400–700 nm and a water vapor transmission rate (WVTR) value of 7.3 × 10⁻⁴ g per m² per day. The measured time to reach 50% of the initial luminance (T₅₀) at initial luminance values of 500, 1000, and 2000 cd m⁻² was 711.6, 287.7, and 78.6 h, respectively, and the extrapolated T₅₀ at 100 cd m⁻² is estimated to be approximately 9804 h, which is comparable to that of the 12 112 h for glass lid-encapsulated QD-LEDs. This result demonstrates that TFE with the ASH films has the potential to overcome the conventional drawbacks of glass lid encapsulation.

The extrapolated T₅₀ at 100 cd m⁻² for the a-SiN_x:H/SiO_xN_y/hybrid SiO_x (ASH)-encapsulated QD-LEDs is estimated to be 9804 h, which is compatible to that of 12112 h for glass lid encapsulated QD-LEDs.