Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Optical Simulation Study of the Improvement of Color-rendering Characteristics of White Light-emitting Diodes by Using Red Quantum-dot Films

적색 양자점 필름을 이용한 백색 발광 다이오드의 연색성 개선에 대한 광학 시뮬레이션 연구

  • Lee, Gi Jung (School of Nano Convergence Technology, Nano Convergence Technology Center, Hallym University) ;
  • Hong, Seung Chan (School of Nano Convergence Technology, Nano Convergence Technology Center, Hallym University) ;
  • Lee, Jung-Gyun (School of Nano Convergence Technology, Nano Convergence Technology Center, Hallym University) ;
  • Ko, Jae-Hyeon (School of Nano Convergence Technology, Nano Convergence Technology Center, Hallym University)
  • 이기정 (한림대학교 나노융합스쿨, 나노융합기술연구소) ;
  • 홍승찬 (한림대학교 나노융합스쿨, 나노융합기술연구소) ;
  • 이정균 (한림대학교 나노융합스쿨, 나노융합기술연구소) ;
  • 고재현 (한림대학교 나노융합스쿨, 나노융합기술연구소)
  • Received : 2021.06.01
  • Accepted : 2021.06.17
  • Published : 2021.08.25
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Abstract

Conventional white light-emitting diodes (LEDs) for lighting applications consist of blue LEDs and yellow phosphors, the spectrum of which lacks deep red. To improve the color-rendering characteristics of white LEDs, a red quantum-dot film was applied to the diffuser plate of LED lighting. The mean free paths of the quantum dots and the concentration of the TiO2 particles in the diffuser plate were adjusted to optimize the optical structure of the lighting. The color-rendering index (CRI) was greater than 90 for most conditions, which demonstrates that adoption of the red quantum-dot film is an effective way for improving the color-rendering properties of conventional white LEDs. The angular dispersion of color coordinates could be removed by utilizing the optical cavity formed between the diffuser plate and the reflector on the bottom of the lighting, where multiple passages of the light through the quantum-dot film reduced the differences in optical path length depending on the viewing angle.

조명에 사용되는 일반적인 백색 발광 다이오드는 청색 발광 다이오드 위에 황색 형광체를 입힌 구조가 보편적이나 발광 스펙트럼상 짙은 적색 성분이 부족해서 조명의 연색성이 떨어지는 문제가 있다. 본 연구에서는 백색 발광 다이오드의 연색 특성을 개선하기 위해 적색 양자점 조명을 백색 조명의 확산판에 적용한 후 광학 시뮬레이션을 이용해 광구조를 최적화하고자 하였다. 양자점의 평균 자유 행정 및 확산판 내 TiO2 입자의 농도를 조절해 연색지수, 휘도 등 광특성을 조사했다. 대부분의 조건에서 연색지수는 90을 넘었고 이는 적색 양자점 필름의 적용이 일반적인 백색 발광 다이오드의 연색 특성을 개선하는 데 효과적인 방법임을 보여준다. 색좌표의 각도 의존성은 확산판과 조명 하단의 반사판 사이에 형성되는 광학적 공동 구조를 활용함으로써 제거할 수 있었는데 이는 공동 내 위치한 양자점 필름을 통한 빛의 다중 투과가 시야각에 따른 광경로의 차이를 줄였기 때문으로 해석된다.

Keywords

Acknowledgement

본 연구는 산업통상자원부와 한국산업기술진흥원의 스마트특성화기반 구축사업을 통한 지원을 받았습니다 (No. P0013743).

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