High efficient and color rendering quantum dots optimized white light emitting diodes

Abstract

Quantum dots applications in illuminants and displays have been offered a lot of expectations due to narrow and tunable emission band. Incompatibility between colloidal QDs and encapsulant and sensitivities to oxygen and moisture are still challenging for applying QDs in white light emitting diode (WLED) devices with high quality. We develop a strategy to incorporate red QDs in silica microspheres (MS) with porous structures by a non-chemical method to achieve luminescent microspheres (LMS). Due to the lattice structure of LMS maintaining large extent of QDs luminescent properties, the fabricated WLED integrated with as prepared LMS and commonly used YAG: Ce yellow phosphors demonstrates not only excellent quality white light on color coordinates (around 0.33 0.33), correlated color temperature (CCT) (5100 to 5500K), and color rendering index (CRI) (Ra=90, R9=95), but also high luminous efficiency reaching up to 142.5 lm/W at 10mA, which is the highest record in previous literatures for QDs optimized WLEDs, and high operational stability in different forward current. LMS technique revealed great potentials for applying QDs in high quality encapsulated WLED with good operational stability.