Challenges and Strategies to Design Phosphors for Future White Light Emitting Diodes

Abstract

Phosphor-converted white-light-emitting diodes (pc-WLEDs) are a commercially successful product for energy-efficient illumination. A large number of reported phosphors exhibit high photoluminescence efficiency but struggle in pc-WLED applications. So what kind of phosphors are required to upgrade the existing pc-WLED? An answer to this question is provided here. The industry is moving toward high-power pc-WLED. For that, issues of thermal instability (at ∼200 °C) and luminescence saturation of phosphors, along with the efficiency drop of the InGaN chip, need to be addressed. Another research direction is to reduce excessive blue light from the present commercial pc-WLED, by replacing the blue-emitting InGaN chip with an ultraviolet (UV)-violet chip. Designing phosphors for high-power pc-WLED with UV-violet chip still remains a challenge. This Perspective highlights the present challenges and provides insights to address them in the future.

Luminescent MOFs (LMOFs): recent advancement towards a greener WLED technology

“…Generally, phosphor converted WLEDs (PC-WLEDs) result in single, compact white light, but have some intrinsic disadvantages such as lower luminous efficiency and limited range of colour tunability owing to poor availability of phosphor materials. [18][19][20] The important metrics that determine the quality of light coming from a device include color temperature and chromaticity. Higher color temperature often signifies that an emissive material produces bluish white light whereas lower color temperature indicates that the emissive material produces warm yellowish white light.…”

Nanoantennas Patterned by Colloidal Lithography for Enhanced Nanophosphor Light Emission

“…Phosphors are key materials for light emission because they feature high conversion efficiencies along with thermal and chemical stability. − For this reason, these photoluminescent materials have been extensively studied and are widely employed in solid-state lasers, fluorescent lamps, light-emitting diodes, displays, or solar cells. − However, increasingly demanding specifications are pushing the development of novel phosphors with tailored properties of interest for smart illumination devices from general lighting to horticulture or healthcare. − In this context, nanocrystals made of inorganic matrices doped with rare-earth (RE) elements, the so-called phosphor nanoparticles or nanophosphors, have gained relevance in recent years not only for their use as nanomarkers for biotechnology , but also because they allow the fabrication of transparent thin coatings of interest for security, labeling, or optoelectronics. − Phosphor nanosizing has also opened the door to the development of phosphor nanoparticle-based optical materials, in which photonic architectures and phosphor thin films are combined to tune RE emission properties with an unprecedented precision. − …”

Energy-saving chromium-activated garnet-structured phosphor-converted near-infrared light-emitting diodes

“…The typical commercial white LED design comprises a blue LED and a garnet structured inorganic chemical compound (phosphor) activated with Ce 3+ . 1 However, the use of visible light (white light) is highly limited for lighting and backlighting applications. [2][3][4][5] It is time to explore the potential of the invisible region of the electromagnetic spectrum, especially NIR light (700-1400 nm), because it is an indispensable requirement for various industrial and medical applications.…”