Study on the Thermal and Optical Performance of Quantum Dot White Light-Emitting Diodes Using Metal-Based Inverted Packaging Structure

• Published in: IEEE transactions on electron devices Vol. 66; no. 7; pp. 3020 - 3027
• Main Authors: Li, Zong-Tao, Song, Cun-Jiang, Qiu, Zi-Yu, Li, Jia-Sheng, Cao, Kai, Ding, Xin-Rui, Tang, Yong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Color temperature; Deviation; Electroluminescence; Electronics; Glass; Image color analysis; Indium tin oxide; Light emitting diodes; Organic light emitting diodes; Packaging; Packaging structure; Phosphors; quantum dot (QD); Quantum dots; stability; Stability criteria; thermal and optical performance; Thermal conductivity; Thermal stability; Thermoelectricity; White light; white light-emitting diode (LED)
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2019.2917010

Quantum dot (QD) white light-emitting diodes (LEDs) are promising devices in illumination and display applications, and the low thermal stability of QDs is one of the biggest problems limiting their practical use. In this paper, we proposed a metal-based inverted packaging (MIP) structure to enhance the thermal performance and stability of QD white LEDs. The results indicate that the thermal power of LED chips can greatly increase the surface temperature of QD white LEDs, especially that of the color-converted layer and the base. Therefore, the LED chip was separated from the QD layer and isolated with low thermal conductivity layers of air and glass using the MIP structure. This successfully reduces the base temperature and constrains the thermal power of the LED chip on the upper phosphor layer, thus enhancing the thermal performance for the QD layer. Consequently, MIP-QD white LEDs have a small deviation of 57.3 K in their correlated color temperature (CCT) and a deviation of 0.29 in their color rendering index (CRI) at injection power values in a wide range of 0.08-1.3 W, with mean values of 4382 K and 90.3, respectively. Moreover, these devices have negligible reduction in their electroluminescence intensity, and CCT and CRI values after aging for 10 h under severe conditions at an injection power of 0.9 W. Consequently, this paper can provide a general guide to enhance the thermal performance and stability of QD white LEDs by separating the thermal power of the LED chip from the QD layer.