Systematic Design of the Color Point of a White LED

Abstract

Lighting is a crucial technology that is used every day. The introduction of the white light emitting diode (LED) that consists of a blue LED combined with a phosphor layer, greatly reduces the energy consumption for lighting. Despite the fast-growing market white LED's are still designed using slow, numerical, trial-and-error algorithms. Here we introduce a radically new design principle that is based on an analytical model instead of a numerical approach. Our design model predicts the color point for any combination of design parameters. In addition the model provides the reflection and transmission coefficients -as well as the energy density distribution inside the LEDof the scattered and re-emitted light intensities. To validate our model we performed extensive experiments on an emblematic white LED and found excellent agreement.Our model provides for a fast and efficient design, resulting in reduction of both design and production costs.

Breakdown of light transport models in photonic scattering slabs with strong absorption and anisotropy

“…Depending on N, we get a set of N + 1 differential equations to solve, as l only takes values l = 0, 1, ..., N. This set is solved with the same method used in Refs. [13,22] to find ψ 0 (z) and ψ 1 (z), to obtain the average intensity…”

“…In photonic scattering media, such as paint, foam, and tissue, the refractive index varies spatially causing incident waves to be scattered and absorbed [1][2][3][4][5][6]. Understanding the transport of light in such scattering media is crucial for many application areas, such as atmospheric and climate sciences [7][8][9][10], oceanography [11,12], biophysics [13][14][15][16], powder technology [17,18], and solid-state lighting [19][20][21][22]. The transport theory describes the propagation of waves in scattering media, notably in a widely used realistic situation such as a slab in three dimensions (3D), as shown in Fig.…”

“…In this paper, we map the unphysical ranges and the relative errors of three popular approximations to the RTE, namely, the P 1 , the P 3 , and the P 3 + δE (4) approximations. The P 3 approximation is a widely used higher-order approximation to RTE [22,[48][49][50], especially popular in biophysics [13,36,38]. The P 3 + δE (4) approximation uses a modified phase function within the P 3 approximation to increase the accuracy of the forward-scattering region [13,36,51] (see Appendix B).…”

Observation of mutual extinction and transparency in light scattering

“…Random scattering of light inside complex materials such as clouds, paint, milk, white LEDs, hair, or human tissue is what makes them appear opaque [1][2][3][4][5]. In these materials, multiple scattering and interference distort the incident wavefront so strongly that the spatial coherence is immensely reduced [6].…”

Efficiency Enhancement of Quantum-Dot-Converted LEDs by 0D–2D Hybrid Scatterers

“…However, the concentrated QDs intensify agglomeration, − reabsorption, − and Förster resonance energy transfer (FRET), − thus, inducing fluorescent quenching of QDs and unsatisfactory light-conversion efficiency (LCE) of QCLEDs. − It is desired that the QDs in QCLEDs absorb more light at a low QD concentration to suppress the fluorescent quenching. Strategies toward improving LCE of QCLED include QD heterostructure engineering, − LED structure optimization, ,− and scattering design. − Nowadays, the quantum efficiency and Stokes shift enhancement of QDs has been well studied by growing a multiple core–shell structure . The optical polymers for QCLED packaging have also received substantial progress .…”