Manganese-activated fluoride phosphors for high-efficacy warm white light-emitting diodes have been limited by low photoluminescence quantum yields. Here, Zhu et al. use an efficient cation exchange reaction to synthesize manganese phosphors with photoluminescence quantum yields as high as 98%.

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Highly efficient non-rare-earth red emitting phosphor for warm white light-emitting diodes

Progress in discovery and structural design of color conversion phosphors for LEDs

A lighting device comprising first and second groups of solid state light emitters, which emit light having peak wavelength in ranges of from 430 nm to 480 nm, and first and second groups of lumiphors which emit light having dominant wavelength in the range of from 555 nm to 585 nm. In some embodiments, if current is supplied to a power line, a combination of (1) light exiting the lighting device which was emitted by the first group of emitters, and (2) light exiting the lighting device which was emitted by the first group of lumiphors would have a correlated color temperature which differs by at least 50 K from a correlated color temperature which would be emitted by a combination of (3) light exiting the lighting device which was emitted by the second group of emitters, and (4) light exiting the lighting device which was emitted by the second group of lumiphors.

Lighting device and lighting method

Light emitting diodes (LEDs) are on the verge of a breakthrough in general lighting, due to their rapidly improving efficiency. Currently, white LEDs with high color rendering are mainly based on wavelength conversion by one or more phosphor materials. This Review first describes how to quantify the quality of a light source, discussing the color rendering index (CRI) and alternative color quality indices. Then, six main criteria are identified and discussed, which should be fulfilled by a phosphor candidate to be considered for actual application in LEDs. These criteria deal with the shape and position of the emission and the excitation spectra, the thermal quenching behavior, the quantum efficiency, the chemical and thermal stability and finally with the occurrence of saturation effects. Based on these criteria, the most common dopant ions (broad-band emitting Eu 2+ , Ce 3+ and Mn 2+ , line-emitting rare earth ions,...) and host compounds (garnets, sulfides, (oxy)nitrides,...) are evaluated. Although many phosphor materials have been proposed in literature in recent years, the number of phosphors effectively fulfilling all six requirements is relatively small.

/pdf/selecting-conversion-phosphors-for-white-light-emitting-20y8tlis4y.pdf

Selecting Conversion Phosphors for White Light-Emitting Diodes

Methods and systems are provided for LED modules that include an LED die integrated in an LED package with a submount that includes an electronic component for controlling the light emitted by the LED die. The electronic component integrated in the submount may include drive hardware, a network interface, memory, a processor, a switch-mode power supply, a power facility, or another type of electronic component.

LED package methods and systems

LED lamps using phosphor downconversion can be designed to replace incandescent or halogen sources with a “warm-white” correlated color temperature (CCT) of 2700−3200 K and a color rendering index (CRI) greater than 90. However, these lamps have efficacies of ∼70% of standard “cool-white” LED packages (CCT = 4500−6000 K; CRI = 75−80). In this report, we describe structural and luminescence properties of fluoride and oxyfluoride phosphors, specifically a (Sr,Ca)3(Al,Si)O4(F,O):Ce3+ yellow-green phosphor and a K2TiF6:Mn4+ red phosphor, that can reduce this gap and therefore meet the spectral and efficiency requirements for high-efficacy LED lighting. LED lamps with a warm-white color temperature (3088 K), high CRI (90), and an efficacy of ∼82 lm/W are demonstrated using these phosphors. This efficacy is ∼85% of comparable cool-white lamps using typical Y3Al5O12:Ce3+-based phosphors, significantly reducing the efficacy gap between warm-white and cool-white LED lamps that use phosphor downconversion.

Energy-Efficient, High-Color-Rendering LED Lamps Using Oxyfluoride and Fluoride Phosphors

An LED device including an LED chip and a lens positioned apart from the chip and coated with a uniform thickness layer of fluorescent phosphor for converting at least some of the radiation emitted by the chip into visible light. Positioning the phosphor layer away from the LED improves the efficiency of the device and produces more consistent color rendition. The surface area of the lens is preferably at least ten times the surface area of the LED chip. For increased efficiency, the reflector and submount can also be coated with phosphor to further reduce internal absorption.

Coated led with improved efficiency

A light source (10) comprises a light engine (16), a base (24), a power conversion circuit (30) and an enclosure (22). The light engine (16) comprises at least one LED (12) disposed on a platform (14). The platform (14) is adapted to directly mate with the base (24) which a standard incandescent bulb light base. Phosphor (44) receives the light generated by the at least one LED (12) and converts it to visible light. The enclosure (22) has a shape of a standard incandescent lamp.

Led-based light bulb

In a method for fabricating a flip-chip light emitting diode device, epitaxial layers (14, 114) are deposited on a growth substrate (16, 116) to produce an epitaxial wafer. A plurality of light emitting diode devices are fabricated on the epitaxial wafer. The epitaxial wafer is diced to generate a device die (10, 110). The device die (10, 110) is flip chip bonded to a mount (12, 112). The flip chip bonding includes securing the device die (10, 110) to the mount (12, 112) by bonding at least one electrode (20, 22, 120) of the device die (10, 110) to at least one bonding pad (26, 28, 126) of the mount (12, 112). Subsequent to the flip chip bonding, a thickness of the growth substrate (16, 116) of the device die (10, 110) is reduced.

Flip chip light emitting diode devices having thinned or removed substrates

A light emitting apparatus comprises: an LED-based light source; a spherical, spheroidal, or toroidal diffuser generating a Lambertian light intensity distribution output at any point on the diffuser surface responsive to illumination inside the diffuser; and a base including a base connector. The LED based light source, the diffuser, and the base are secured together as a unitary LED lamp installable in a lighting socket by connecting the base connector with the lighting socket. The diffuser is shaped and arranged respective to the LED based light source in the unitary LED lamp to conform with an isolux surface of the LED based light source. The base is operatively connected with the LED based light source in the unitary LED lamp to electrically power the LED based light source using electrical power received at the base connector.

Boris Kolodin

Papers

Energy-Efficient, High-Color-Rendering LED Lamps Using Oxyfluoride and Fluoride Phosphors

Coated led with improved efficiency

Led-based light bulb

Flip chip light emitting diode devices having thinned or removed substrates

Led lamp with uniform omnidirectional light intensity output