Interdielectric Layer Engineering for Reliable Monolithic Integration of ITZO TFT Backplanes and InP QLEDs

Area of Science:

• Materials Science
• Electronics Engineering
• Display Technology

Background:

• Monolithic integration of thin-film transistors (TFTs) and quantum-dot light-emitting diodes (QLEDs) is crucial for advanced display technologies.
• The dielectric environment significantly impacts the electrical performance and stability of integrated TFT-QLED pixels.

Purpose of the Study:

• To investigate the influence of different interdielectric configurations on indium-tin-zinc oxide (ITZO) TFT stability and QLED driving behavior.
• To elucidate the effects of dielectric composition and interfacial chemistry on monolithic TFT-QLED pixel performance.

Main Methods:

• Systematic investigation of single-layer Al2O3, single-layer SiO2, and an Al2O3/SiO2 bilayer as interdielectrics.
• Fabrication and characterization of ITZO TFTs and their integration with InP QLEDs.
• Analysis of electrical parameters, current leakage, and optical performance of the integrated pixels.

Main Results:

• The Al2O3/SiO2 bilayer demonstrated superior current leakage suppression and compatibility with solution-processed QLED fabrication.
• Despite hydrogen-induced donor defects in the ITZO channel, the bilayer enabled stable pixel operation with high TFT performance (mobility: 24.82 cm2 V-1 s-1, on/off ratio: 8.78 × 10^9).
• Integrated pixels achieved a peak luminance of 9,488.8 cd m-2 and an external quantum efficiency of 7.15% with stable electroluminescence spectra.

Conclusions:

• Interdielectric layer engineering is critical for reliable monolithic TFT-QLED operation.
• Balancing hydrogen-induced voltage threshold shifts with process robustness is essential for next-generation active-matrix display technologies.
• The Al2O3/SiO2 bilayer presents a promising approach for stable and high-performance monolithic TFT-QLED displays.