Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Effect of Microstructure of Quantum Dot Layer on Electroluminescent Properties of Quantum Dot Light Emitting Devices

양자점 층의 미세구조 형상이 양자점 LED 전계 발광 특성에 미치는 효과

  • Yoon, Sung-Lyong (Department of Nano-system Engineering, Inje University) ;
  • Jeon, Minhyon (Department of Nano-system Engineering, Inje University) ;
  • Lee, Jeon-Kook (Interface Control Research Center, Korea Institute of Science and Technology)
  • 윤성룡 (인제대학교 나노시스템공학과) ;
  • 전민현 (인제대학교 나노시스템공학과) ;
  • 이전국 (한국과학기술연구원 계면제어연구센터)
  • Received : 2013.07.15
  • Accepted : 2013.08.01
  • Published : 2013.08.27
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Abstract

Quantum dots(QDs) with their tunable luminescence properties are uniquely suited for use as lumophores in light emitting device. We investigate the microstructural effect on the electroluminescence(EL). Here we report the use of inorganic semiconductors as robust charge transport layers, and demonstrate devices with light emission. We chose mechanically smooth and compositionally amorphous films to prevent electrical shorts. We grew semiconducting oxide films with low free-carrier concentrations to minimize quenching of the QD EL. The hole transport layer(HTL) and electron transport layer(ETL) were chosen to have carrier concentrations and energy-band offsets similar to the QDs so that electron and hole injection into the QD layer was balanced. For the ETL and the HTL, we selected a 40-nm-thick $ZnSnO_x$ with a resistivity of $10{\Omega}{\cdot}cm$, which show bright and uniform emission at a 10 V applied bias. Light emitting uniformity was improved by reducing the rpm of QD spin coating.At a QD concentration of 15.0 mg/mL, we observed bright and uniform electroluminescence at a 12 V applied bias. The significant decrease in QD luminescence can be attributed to the non-uniform QD layers. This suggests that we should control the interface between QD layers and charge transport layers to improve the electroluminescence.

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