ITO DBR electrodes fabricated on PET substrate for organic electronics

Area of Science:

• Materials Science
• Optoelectronics
• Thin Film Technology

Background:

• Distributed Bragg reflectors (DBRs) are crucial optical components.
• Flexible substrates like PET require specialized fabrication techniques for conductive coatings.
• Indium tin oxide (ITO) is a widely used transparent conductive material.

Purpose of the Study:

• To propose a novel conductive DBR fabricated entirely from ITO on a PET substrate.
• To achieve a large refractive index contrast between alternating ITO layers.
• To optimize the DBR for high reflectance and low sheet resistance on a flexible platform.

Main Methods:

• Fabrication of dense ITO films using long-throw radio-frequency magnetron sputtering at room temperature.
• Creation of porous ITO films via supercritical CO2 (SCCO2) treatment at 60 °C.
• Alternating deposition of dense and porous ITO layers to form the DBR structure.

Main Results:

• Achieved a significant index contrast of 0.59 between dense and porous ITO films in the blue spectral range.
• A 4.5-period ITO DBR on PET substrate demonstrated 85.1% reflectance at 475 nm.
• The fabricated DBR exhibited a sheet resistance of 47 Ω/◻.

Conclusions:

• The proposed single-material ITO DBR on PET substrate is a viable approach for flexible optoelectronic devices.
• The combination of sputtering and SCCO2 treatment effectively creates the necessary index contrast.
• The achieved optical and electrical properties are promising for applications requiring flexible conductive optics.