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Optical Enhancement in Optoelectronic Devices Using Refractive Index Grading Layers.
Illhwan Lee1, Jae Yong Park1, Seungo Gim1
1Department of Materials Science and Engineering, Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH) , Pohang, Gyeongbuk 790-784, Korea.
ACS Applied Materials & Interfaces
|January 23, 2016
Summary
A refractive index grading layer (RIGL) was added to multilayer barrier films to reduce Fresnel reflection. This enhancement significantly boosted optical transmittance and luminance in organic electronic devices.
Area of Science:
- Materials Science
- Optics
- Nanotechnology
Background:
- Multilayer barrier films are crucial for protecting sensitive electronic components.
- Fresnel reflection at interfaces between materials like Si(x)N(y) and SiO2 reduces optical transmittance.
- Existing films face limitations in optical performance due to refractive index mismatches.
Purpose of the Study:
- To enhance the optical transmittance of multilayer barrier films.
- To reduce Fresnel reflection using a refractive index grading layer (RIGL).
- To investigate the impact of RIGL on the performance of organic electronic devices.
Main Methods:
- Insertion of a refractive index grading layer (RIGL) into multilayer barrier films.
- Optimization of grading structures using an optical simulator to minimize Fresnel reflection.
- Measurement of optical transmittance in the visible wavelength region.
- Evaluation of luminance enhancement in organic light-emitting diodes (OLEDs).
Main Results:
- The RIGL effectively reduced Fresnel reflection caused by refractive index differences.
- Average optical transmittance in the visible region was increased to 89.6% with the RIGL, compared to 82.6% without.
- Luminance in OLEDs was enhanced by 14.5% (from 10,190 to 11,670 cd m(-2) at 30 mA cm(-2)) after applying the grading structure.
Conclusions:
- The optimized grading structure with RIGL significantly improves optical transmittance in multilayer barrier films.
- The enhanced optical properties translate to improved performance in organic electronic devices, specifically OLEDs.
- This approach offers a pathway for developing cost-effective, flexible organic electronics with superior optical characteristics.
