Thermal Analysis And Performance Optimization Of Quantum Dot LEDs

Quantum dots(QDs)have attracted extensive research interest due to their unique optical characteristics and the ability to manufacture high-performance LEDs.QDs are commonly used as down-conversion materials in LED backlighting to improve the display color gamut,which has led to the vigorous development of QDs in the display and lighting market.In the past few years,QDs converted LEDs(QCLEDs)have received tremendous improvements in efficiency and lifetime.However,the optical performance of QDs is affected by their inherent thermal sensitivity characteristics and agglomeration in LEDs.When QDs are used as light conversion material,the thermal issue becomes more apparent due to the Stokes-shift between absorption and emission peaks,which makes QDs a secondary heat source.Traditional fluorescent conversion materials,such as yttrium aluminum garnet yellow phosphor(YAG:Ce³⁺),are irregularly shaped particles of micron size and have a moderate heat dissipation capacity.In contrast,QDs are nano-sized particles with a regular shape and exhibit different quenching characteristics from phosphors because of the large overlap between absorption and emission peaks.Hence the QDs are required to be uniformly dispersed in the package.However,the host polymer matrices for QDs in LEDs materials have low thermal conductivity.For this reason,QDs in LED packages cause more serious thermal problems than conventional phosphors.The temperature difference can be attributed to the relatively stronger heat accumulation in QDs than conventional phosphors.However,this difference has not been clearly illustrated by thermal simulations,and precise thermal control of the QDs in the LED package is urgently needed to promote performance optimization.The main work accomplished is as follows:1.Design a simulation model suitable for QCLED and optimize the packaging method.A microspheres model for thermal simulation was developed on the basis of the optical and thermal characteristics and the analysis of the thermal accumulation effect of QDs in polymer matrices.Simulation based on the microsphere model displays more accurate temperature and temperature distribution close to the actual situation of the QDs in QCLEDs.This study provides theoretical guidance for application of QCLEDs and design of package structure.2.Optimize the package structure of QCLED.Based on the developed thermal simulation model,a new packaging architecture was designed to reduce the operating temperature and optimized the temperature distribution of the QDs in LEDs,and QCLEDs with different package architectures were developed to validate the simulation results.Tests show that the bottom package architecture can reduce the temperature of QDs in LEDs by12.5?at 150 m A,and the temperature reduction range is as high as 13.56%.3.Introduce thermal conductive fillers in packaging matrix to reduce the operating temperature of QCLEDs.h BN(hexagonal boron nitride)was found to be an excellent heat dissipation auxiliary material for LEDs.h BN filler effectively reduces the operation temperature of the QCLED by promoting heat transfer from QDs to surrounding environment.This research systematically studied the optical characteristic and thermal behavior of QDs in LED package,aiming to reduce the operation temperature of QCLEDs.Based on the study a new simulation model for QDs was developed and highly improved the accuracy of thermal simulation results,which provides a significant guidance to the design of QCLED package architecture and the optimization of QDs in optoelectronic devices.Finally,an optimized LED package architecture was developed that can be practically implemented and effectively reduce the operation temperature of the QCLEDs.