Optical Modeling And Packaging Analysis Of Quantum Dots Converted Light-emitting Diodes

Quantum dots-converted light-emitting diodes?QDs-LED? is a new candidate of high quality solid-state lighting?SSL? device. Since the packaging structure of QDs-LED varies from different application, to build the optical model of QDs-LED is essential for its packaging design and fabrication. Based on this, this dissertation mainly studies the optical modeling and packaging analysis of QDs-LED and achieves some works as following:The double integrating sphere?DIS? system has been designed and built to test the reflectance, transmittance and collimating transmittance of QDs-polymer film. The basic optical parameters such as scattering coefficient, absorption coefficient and anisotropy coefficient have been calculated via inverse adding doubling?IAD? algorithm. Finally, the measurement error of DIS system has been validated as less than 1%, and the calculation error of IAD algorithm was less than 10-5, which indicates that this method could obtain accurate value of QDs' optical properties.The CuInS₂/ZnS core/shell QDs have been synthesized, and a series of QDs-PMMA film with different thickness and QDs concentration has been fabricated. The transmittance, reflectance and collimating transmittance of QDs films have been tested, and the optical properties have been calculated. It has been found that the QDs' absorption coefficient towards blue light increased with the increasing thickness and concentration, while there was no apparent change in the absorption coefficient towards yellow light. The scattering coefficient of QDs toward yellow light is larger than that toward blue light, which indicates that more yellow light would be scattered in the QDs film than blue light. Meanwhile, QDs' anisotropy coefficient towards blue light is larger than that toward yellow light.Based on the calculated optical properties of QDs, the optical model of QDs-LED has been built. Three typical QDs-LED packaging have been simulated via Monte-Carlo method, and effect of packaging structure on the optical performance of QDs-LED has been analyzed, finally the simulation results have been validated via experiments. It was found that the light extraction efficiency?LEE? of LED chip is strongly relates to the reflective index of surrounding encapsulation, when the reflective index of encapsulation is less than that of the LED chip, the LEE of LED chip can be improved. The optical power of QDs' emission light is strongly relates to the optical path of blue light in the QDs layer, the longer the optical path, the more the QDs' emission power. Furthermore, according to the eye sensitivity function, equivalent power of blue light from LED chip results in less luminous efficiency than QDs emission yellow light. More QDs emission results in higher luminous efficiency.