Types Of Light-emitting Diodes Research Articles

Highly efficient blue-light-excitable ultra-broadband orange-emitting Mg2.5Y1.5Al1.5Si2.5O12:Ce3+ garnet phosphors for solid-state lighting

Lighting and display technologies are revolutionized by the invention of YAG:Ce3+ phosphors driven by InGaN blue light-emitting diode (LED). Yet, the faint emission components in the red spectral region from typical LED devices can cause circadian rhythm disorders and aesthetic fatigue of the human eye. Developing broadband orange-emitting phosphor with abundant red coverage is one of the approaches for addressing this challenging problem. Herein, an innovative ultra-broadband orange-emitting Mg2.5Y1.5Al1.5Si2.5O12:Ce3+ (MYASO:Ce3+) garnet phosphor is successfully reported to bridge the above gap. The representative MYASO:4%Ce3+ sample exhibits an unexpectedly luminescence band with the full width at half maximum (FWHM) of up to 155 nm, the high thermal robustness (58%@423 K), and satisfactory internal quantum efficiency of 67% upon 465 nm blue light excitation. Such a large FWHM value results from the occupation of a single crystallographic site of Ce3+ in the dodecahedral [YO8] position of MYASO garnet host. Red-shift emission with respect to commercial YAG:Ce3+ is mainly attributed to the cooperative effect of the enhanced crystal field strength and increased Stokes shift. The emission intensity reduction at the high-temperature environment of MYASO:4%Ce3+ is derived from the enhancement of the thermal cross-relaxation associated with the larger Stokes shift (4839 cm−1). The resulting high-quality warm white LED device fabricated from the optimal MYASO:4%Ce3+ sample shows a satisfactory color rendering index (CRI = 84), comfortable correlated color temperature (CCT = 4032 K) and an excellent luminous efficacy (LE = 58.7 lm W−1) under a 60 mA drive current. These findings stimulate the exploration of ultra-broadband orange-emitting phosphors with abundant red emission to fabricate high-CRI warm-white LEDs for healthy solid-state lighting.

Effect of light curing units on color stability and mechanical properties of resin cements after aging

This study aimed to evaluate the color stability, Martens hardness (HMV), and modulus of elasticity (Eit*) of resin cements light-cured using two types of light-emitting diodes (LED) subjected to ultraviolet (UV) aging. Two resin cements were used: light-cured (RelyX Veener) and dual-cured (Variolink II). Forty discs were confectioned for each resin cement (with a diameter of 5 mm and thickness of 1.5 mm). Half of the samples were light-cured by a Radii-cal singlewave and the other half by a Valo® polywave. The specimens were then stored at 37 °C and 100% relative humidity for 24 h to ensure complete polymerization. Baseline evaluations of the color alteration, HMV, and Eit* were performed. The specimens were aged for 252 h in an UV-accelerated aging chamber. Then, a final analysis was performed. Two-way repeated-measures ANOVA was performed on the color changes. Meanwhile, three-way repeated-measures ANOVA followed by Tukey´s test was performed on HMV and Eit* to compare the means (α = 0.05). With regard to the color alteration (ΔE), there was no statistically significant difference between the materials or between the light curing units (p > 0.05). With regard to the mechanical properties, Valo® promoted high values of HMV and Eit* compared with Radii-cal (p < 0.05). With regard to the resin cements, Variolink II showed higher HMV and Eit* values than RelyX Veneer (p < 0.05), except for Eit* after UV aging. The light-curing unit influenced the mechanical properties but not the color stability of the resin cements.

The Effects of Light Treatments on Growth and Flowering Characteristics of Oncidesa Gower Ramsey ‘Honey Angel’ at Different Growth Stages

In our previous work, we observed that Oncidesa Gower Ramsey ‘Honey Angel’ (HA) plants became stunned on hot summer afternoons, and the seasonal trend in solar radiation affected its production schedule by limiting flower yield and quality. The objective of this work was to study the growth and flowering characteristics of HA pseudobulbs at three stages of growth (G2–G4) in response to three types of light-emitting diode (LED) lighting treatments, including full spectrum (FS), deep red/white-medium blue (DR/W-MB), and deep red/white-low blue (DR/W-LB), for two additional time intervals. The supplementary LED lighting time intervals (S) applied daily were carried out for 1 h (4:00~5:00 a.m., as S-1) or 2 h (4:00~6:00 a.m., as S-2) from March to September, 2022. Natural light without supplemental lighting was the control. The length of pseudobulb (PL), width of pseudobulb (PW), thickness of pseudobulb (PT), length of inflorescence (FL), number of branches (FB), number of florets (FN), and days to flowering (FD) per plant were recorded andcalculated when 80% of florets became mature. Light treatments significantly affected all pseudobulb growth and flower quality traits at different Gs, especially pseudobulb length (PL) and flower number (FN) under different LED types and lighting time intervals. MB-1 treatment promoted PT at both G3 and G4, whereas MB-2 treatment increased PW at both G2 and G4. Both MB-1 and LB-1 treatments had augmented effects on PL, respectively, at G2 and G3. The PW, FL, FB, and FN increased with additional light time and reached maxima under MB-2 treatment at G4 compared to other treatments and controls. Early flowering and an increased number of flowers at G4 were observed in plants grown under MB-2 treatment. Controlling light quality and supplementary light time intervals enables the production of HA plants with the desired growth and flowering quality characteristics of the pseudobulbs.

First Nighttime Light Spectra by Satellite—By EnMAP

For the first time, nighttime VIS/NIR—SWIR (visible and near-infrared—shortwave infrared) spectra from a satellite mission have been analyzed using the EnMAP (Environmental Mapping and Analysis Program) high-resolution imaging spectrometer. This article focuses on the spectral characteristics. Firstly, we checked the spectral calibration of EnMAP using sodium light emissions. Here, By applying a newly devised general method, we estimated shifts of +0.3nm for VIS/NIR and −0.2nm for SWIR; the uncertainties were found to be within the range of [−0.4nm,+0.2nm] for VIS/NIR and [−1.2nm,+1.0nm] for SWIR. These results emphasize the high accuracy of the spectral calibration of EnMAP and illustrate the feasibility of methods based on nighttime Earth observations for the spectral calibration of future nighttime satellite missions. Secondly, by employing a straightforward general method, we identified the dominant lighting types and thermal emissions in Las Vegas, Nevada, USA, on a per-pixel basis, and we considered the consistency of the outcomes. The identification and mapping of different types of LED (light-emitting diode) illuminations were achieved—with 75% of the identified dominant lighting types identified in VIS/NIR—as well as high- and low-pressure sodium and metal halide, which made up 22% of the identified dominant lighting types in VIS/NIR and 29% in SWIR and other illumination sources, as well as high temperatures, where 33% of the identified dominant emission types in SWIR were achieved from space using EnMAP due to the elevated illumination levels in the observed location. These results illustrate the feasibility of the precise identification of lighting types and thermal emissions based on nighttime high-resolution imaging spectroscopy satellite products; moreover, they support the specification of spectral characteristics for upcoming nighttime missions.

Optimization of LED-Based Solar Simulators for Cadmium Telluride and Microcrystalline Silicon Solar Cells

Solar simulators are instruments used for controllable measurements of the properties of solar cells in indoor environments. The purpose of this paper is to examine the peculiarities of the photoresponses of CdTe/CdSeTe and microcrystalline Si solar cells and to reveal the pathways to reduction of spectrum mismatch effects when using light-emitting diode (LED)-based or hybrid LED and halogen lamp-based solar simulators of an A+-class spectrum with a small number of sources. While only four different LED types are needed to achieve an A+-class spectrum under updated IEC 60904-9:2020 standard requirements, as demonstrated by our results, additional ultraviolet LEDs are necessary to reduce the spectrum mismatch. For hybrid solar simulator configurations, the combination of cool white LED arrays and halogen emitters can serve as a main light source. Optimized for both solar cell types, hybrid simulators have a lower spectral deviation and better spectrum coverage compared to LED-only simulators with the same number of distinct source types. In addition, our results predict lower spectral mismatch errors for optimized simulators when compared with conventional Xe lamp-based simulators.

A 3D printed photoreactor for investigating variable reaction geometry, wavelength, and fluid flow.

Research in the field of photochemistry, including photocatalysis and photoelectrocatalysis, has been revitalized due to the potential that photochemical reactions show in the sustainable production of chemicals. Therefore, there is a need for flexible photoreactor equipment that allows for the evaluation of the geometry, light wavelength, and intensity of the vessel, along with the fluid flow in various photochemical reactions. Light emitting diodes (LEDs) have narrow emission spectra and can be either pulsed or run continuously; being flexible, they can be arranged to fit the dimensions of various types of the reactor vessel, depending on the application. This study presents a 3D printed photoreactor with the ability to adjust distances easily and switch between high-power LED light sources. The reactor design utilizes customized printed circuit boards to mount varying numbers and types of LEDs, which enables multiple wavelengths to be used simultaneously. These LED modules, comprised of heat sinks and cooling fans, fulfill the higher heat dissipation requirements of high-power LEDs. The flexibility of the reactor design is useful for optimizing the reaction geometry, flow conditions, wavelength, and intensity of photochemical reactions on a small scale. The estimates for incident light intensity under five possible reactor configurations using ferrioxalate actinometry are reported so that comparisons with other photoreactors can be made. The performance of the photoreactor for differing vessel sizes and distances, in both the flow and batch modes, is given for a photochemical reaction on 2-benzyloxyphenol-a model substance for lignin and applicable in the production of biobased chemicals.

Effect of Light-Emitting Diodes on Different Growth Stages of Rice

Effect of red and blue light on seed germination and seedling growth were studied in rice (Oryza sativa L.). Rice seeds were germinated in dark (control) and two types of light emitting-diodes (LED): red and green in the laboratory. The photoperiod of 6 h light and 18 h dark for LEDs treatment and 24h dark treatments with 24/18 ± 2 °C day/night temperature and 78± 2 % relative humidity were maintained in the growth room. Seed germination percentage under red light increased significantly when compared with the control; however, in blue light, germination percent decreased with little difference. First leaf length, first leaf blade length, root length, seedling fresh and dry weight increased under red and blue lights in most of the varieties. Highest germination (98%), longest root (8.18 cm) and high seedling fresh weight (0.527 g) and seedling dry weight (0.061g) in BRRIdhan71 and longest leaf in BRRIdhan75, were recorded under red light. Highest germination (96%), seedling fresh weight (0.414g) and seedling dry weight (0.047g) in BRRIdhan71, longest first leaf (6.50 cm) in BRRIdhan75 and longest root (9.37 cm) in BRRIdhan87 were recorded under blue light. First leaf blade showed only positive correlation with root length (r = 0.489), whereas seedling fresh weight showed complete correlation with seedling dry weight (r =1). Response index was positive in root length, seedling fresh and dry weight under red light. First leaf blade length, seedling fresh and dry weight had the positive response index under blue light. Within the visible spectrum, varying wave lengths of red and blue light alone altered the growth and morphology of rice seedlings, and variable reactions to illumination depended on the rice varieties, necessitating further research.
 Environ. Sci. & Natural Resources, 13(1&2): 56-62, 2020

Ultralow-voltage operation of light-emitting diodes

For a light-emitting diode (LED) to generate light, the minimum voltage required is widely considered to be the emitter’s bandgap divided by the elementary charge. Here we show for many classes of LEDs, including those based on perovskite, organic, quantum-dot and III–V semiconductors, light emission can be observed at record-low voltages of 36–60% of their bandgaps, exhibiting a large apparent energy gain of 0.6–1.4 eV per photon. For 17 types of LEDs with different modes of charge injection and recombination (dark saturation currents of ~10−39–10−15 mA cm−2), their emission intensity-voltage curves under low voltages show similar behaviours. These observations and their consistency with the diode simulations suggest the ultralow-voltage electroluminescence arises from a universal origin—the radiative recombination of non-thermal-equilibrium band-edge carriers whose populations are determined by the Fermi-Dirac function perturbed by a small external bias. These results indicate the potential of low-voltage LEDs for communications, computational and energy applications.

Deep‐Red‐Emitting Colloidal Quantum Well Light‐Emitting Diodes Enabled through a Complex Design of Core/Crown/Double Shell Heterostructure

AbstractExtending the emission peak wavelength of quasi‐2D colloidal quantum wells has been an important quest to fully exploit the potential of these materials, which has not been possible due to the complications arising from the partial dissolution and recrystallization during growth to date. Here, the synthetic pathway of (CdSe/CdS)@(1‐4 CdS/CdZnS) (core/crown)@(colloidal atomic layer deposition shell/hot injection shell) hetero‐nanoplatelets (NPLs) using multiple techniques, which together enable highly efficient emission beyond 700 nm in the deep‐red region, is proposed and demonstrated. Given the challenges of using conventional hot injection procedure, a method that allows to obtain sufficiently thick and passivated NPLs as the seeds is developed. Consequently, through the final hot injection shell coating, thick NPLs with superior optical properties including a high photoluminescence quantum yield of 88% are achieved. These NPLs emitting at 701 nm exhibit a full‐width‐at‐half‐maximum of 26 nm, enabled by the successfully maintained quasi‐2D shape and minimum defects of the resulting heterostructure. The deep‐red light‐emitting diode (LED) device fabricated with these NPLs has shown to yield a high external quantum efficiency of 6.8% at 701 nm, which is on par with other types of LEDs in this spectral range.

Flexible liquid metal display using 3-Aminopropyl triethoxysilane-treated light emitting diodes (LEDs) array

In recent years, the fabrication of flexible electronic devices has been focused on the use eutectic gallium‑indium (EGaIn) liquid metal (LM) materials with polydimethylsiloxane (PDMS) microfluidics, which are less toxic. The flexible electronic devices offer the advantage of attaining various shapes as they are liquid at room temperature. However, discontinuities in the circuit occur while bending of the flexible LM circuit as EGaIn LM easily leaks into the space between the electrical components such as light-emitting diodes (LEDs) and PDMS microfluidic channels. Thus, the present study proposes use of a (3-Aminopropyl) triethoxysilane (APTES)-treatment method to create a circuit consisting of 100 μm channels based on EGaIn. The strategy enhances the bonding strength of surface mount device (SMD) such as LEDs and PDMS. The circuit mold to be patterned with the PDMS has been made with a 3D printer and coated with a polymer as buffer layer to allow the PDMS to detach the circuit mold easily. The change in resistance of the EGaIn LM by varying the bending angle from 0° to 60° is presented for one channel through the I-V curves. Additionally, effect of bending on the on/off state of an APTES-treated SMD type LED has been studied. Furthermore, the proposed method has been employed for developing a 5 × 1 LED array circuit. An Arduino has been employed to express a 5 × 5 LED array circuit in the form of letters. Hence, a flexible device with improved stability has been demonstrated using EGaIn LM that does not overflow while bending due to an enhanced binding force between the PDMS and SMD-type LEDs as a result of the APTES-treatment processing.

Characterization of “cool” and “warm” white light-emitting diodes for low-cost spectrophotometry

The emission properties of “cool” and “warm” white light-emitting diodes were studied in the context of low-cost spectrophotometry. The suitability of pulse-width modulation as a method to control the diode brightness was examined. Both types of light-emitting diode demonstrated emission standard deviation minima at a pulse-width modulation frequency greater than 2000 Hz. The functional wavelength ranges of the light-emitting diodes were approximated using the linearity of brightness as a function of pulse-width modulation duty-cycle and the root mean squared deviation from mean for absorbance measurements. Both light emitting diode types demonstrated good stability in absorbance measurements over long operation times. The “warm” light emitting diode demonstrated a broader range of wavelengths useful for spectrophotometry.

Effect of various light spectra on amino acids and pigment production of Arthrospira platensis using flat-plate photobioreactor

Today, the use of nutrients derived from natural bioactive compounds application in the food, pharmaceutical, and cosmetic industries is on the increase. This paper aimed to evaluate the amino acids profile (essential and non-essential) and pigments composition (chlorophyll a, carotenoids, and phycocyanin) of Arthrospira platensis (a blue-green microalga) cultivation in a flat-plate photobioreactor under various types of light-emitting diodes (red: 620–680 nm, white: 380–780 nm, yellow: 570–600nm, blue: 445–480 nm). The maximum biomass concentration (604.96 mg L−1) occurred when the red LED was applied for cultivation, and the minimum biomass concentration (279.39 mg L−1) was obtained under blue LED. The sequence of pigments and amino acids concentrations (mg L−1 culture volume) was approximately in accordance with the biomass productivity. It means the red light produces the maximum concentration of pigments (chlorophyll a: 5.42, carotenoids: 2.92, phycocyanin: 67.54 mg L−1) and amino acids (essential amino acids: 110.47, nonessential amino acids: 179.10 mg L−1). Nevertheless, when these values were measured in mg per g of dry weight, the utmost contents were observed in microalgal products cultivated under blue LED. These consequences are due to the highest cell productivity and the most extended length of cells that occurred under red and blue LEDs, respectively.

Piezoresistive Effect with a Gauge Factor of 18 000 in a Semiconductor Heterojunction Modulated by Bonded Light-Emitting Diodes.

Giant piezoresistive effect enables the development of ultrasensitive sensing devices to address the increasing demands from hi-tech applications such as space exploration and self-driving cars. The discovery of the giant piezoresistive effect by optoelectronic coupling leads to a new strategy for enhancing the sensitivity of mechanical sensors, particularly with light from light-emitting diodes (LEDs). This paper reports on the piezoresistive effect in a 3C-SiC/Si heterostructure with a bonded LED that can reach a gauge factor (GF) as high as 18 000. This value represents an approximately 1000 times improvement compared to the configuration without a bonded LED. This GF is one of the highest GFs reported to date for the piezoresistive effect in semiconductors. The generation of carrier concentration gradient in the top thin 3C-SiC film under illumination from the LED coupling with the tuning current contributes to the modulation of the piezoresistive effect in a 3C-SiC/Si heterojunction. In addition, the feasibility of using different types of LEDs as the tools for modulating the piezoresistive effect is investigated by evaluating lateral photovoltage and photocurrent under LED's illumination. The generated lateral photovoltage and photocurrent are as high as 14 mV and 47.2 μA, respectively. Recent technologies for direct bonding of micro-LEDs on a Si-based device and the discovery reported here may have a significant impact on mechanical sensors.

An Approach for Designing Mixed Light-Emitting Diodes to Match Greenhouse Plant Absorption Spectra

We report a methodological approach for simulating luminary output radiation, which is achieved by mixing light-emitting diodes (LEDs) in order to match any plant absorption spectrum. Various recorded narrow-band LED spectra of different colors were first characterized and then fitted with a multi-Gaussian model. An optimizing procedure computed the optimal weighting of the relevant parameters so as to minimize the discrepancy between the combined spectrum and the reference target curve. The particle swarm optimization (PSO) method was applied because it is the most suitable technique for mono-objective situations. Within the useful spectral interval, the worst relative standard deviation between the optimized curve and recorded LED spectral power distribution (SPD) was 3.4%. When combining different LED types, the simulated light output showed that we could limit ourselves to selecting only five colored sources. This work will help us to design an optimized 200 W laboratory luminaire with a pulse-width switched-mode power supply.

Effects of replacing outdoor lighting with white LEDs with different correlated color temperatures on the attraction of nocturnal insects

Currently, many sources of outdoor lighting are being replaced with light-emitting diodes (LEDs). Although conventional light sources that emit light in the ultraviolet range are generally more attractive to nocturnal insects than LEDs, which typically do not emit ultraviolet light, it has not been established whether there are differences in attraction to white LEDs that differ in correlated color temperature (CCT). We experimentally compared the attraction of insects to fluorescent mercury vapor (MV) lamps and white LEDs with two different CCTs (5000 and 2200 K) using custom-made flight intercept traps in Hiroshima Prefecture, western Japan. Although the attraction of lepidopterans and coleopterans to white LEDs was approximately 85–90% lower than that to MV lamps, hemipterans, dipterans, and hymenopterans were found to be almost equally attracted to the 5000-K LEDs and MV lamps. Our results suggest that spectral tuning of LEDs can affect the attraction of insects belonging to various orders, including Coleoptera and Hemiptera, although we did not find a significant difference between the two LED types with respect to the attraction of moths or flies. These findings indicate that the effects of converting outdoor light sources can be reduced by customizing spectral compositions.

Electrical model formulation for multicolor light‐emitting diode modules and its application to design dimmable driver

SummaryA multicolor light‐emitting diode (LED) module comprises LED chips of more than one type or color and is frequently used for spectrally tunable lighting applications. In this paper, electrical models of such multicolor LED modules are formulated taking two basic circuit configurations into account, namely, (i) conventional, where a parallel string is made of one particular LED type, and (ii) nonconventional, where a parallel string is composed of different LED types. For deriving the model equations, the basic exponential model of a single LED chip has been applied, which is experimentally found to be the suitable option out of the four existing models, namely, linear, parabolic, exponential, and modified Shockley models. The formulated models are experimentally validated, results of which show maximum deviations of 4.71% and 4.19% from the measured data in the nonlinear and the linear operating regions, respectively. The formulated models are utilized to design dimmable, isolated LED drivers for red‐green‐blue (R‐G‐B) LED module. Performance evaluation of the drivers is conducted in Matlab‐Simulink. The results reveal the satisfactory operation of the LED modules in terms of current and power regulation, branch current matching, and fast response and thus establish the effectiveness of the proposed algorithm.

Time-varying Photosynthetic Photon Flux Density and Relative Spectral Photon Flux Density Distribution to Improve Plant Growth and Morphology in Plant Factories with Artificial Lighting

In contrast to fluorescent lamps and high-power sodium lamps, the use of light-emitting diode (LED) lamps enables the control of not only photosynthetic photon flux density (PPFD) at the plant level, but also the relative spectral photon flux density distribution (RSPD) of light because of the variety, even at different times of day, of producible light emitted by LEDs of different types. Effects of the spectral photon flux density on plant growth and morphology have been investigated using several types of LEDs and plant species. However, few studies on lighting methods with time-varying PPFD or RSPD have been published to date. In this paper, we summarize the effects of time-varying PPFD on the net photosynthetic rate (Pn) and those of time-varying RSPD on plant growth and morphology. Detailed modeling studies have been conducted on the reactions of the photosynthetic pathway under time-varying PPFD at a cycle of milliseconds to seconds. The results of these modeling studies and actual measurements of Pn under pulsed light clearly indicate that pulsed light is not advantageous to improve Pn. Although the integrated PPFD of blue and red light was unchanged, the growth of leaf lettuce was promoted by asynchronous irradiation with blue light and red light compared with growth under simultaneous irradiation. We think that blue-light monochromatic irradiation promotes leaf elongation through leaf expansion as a primary factor in the enhancement of plant growth. In addition, changes in leaf photosynthetic capacity caused by blue-light monochromatic irradiation may be involved in plant growth promotion. An increasing number of studies have investigated the effects of time-varying RSPD on plants. However, the mechanisms underlying these effects remain to be elucidated.

The application of LED illumination and intelligent control in plant factory, a new direction for modern agriculture: A Review

Because of its cold light source and adjustable spectrum characteristics, light-emitting diode (LED) is widely used in modern agriculture, it can promote the growth and photomorphogenesis of the plant, also can improve yield and quality. Here, we introduce the advantages of LED over traditional light sources, and analyze the effects of different wavelengths of light on phototrophic plants and the ways in which different light detection systems interact in plants. We also analyze the effects of LED illumination on plants, the response of plants to LED illumination systems. In addition, we summarize the typical LED supplement light devices and intelligent control system in the world, and introduce their working methods and advantages respectively. Finally, we look forward to the future development direction and application prospects of LED with the intelligent control and machine in modern agriculture.

Effect of micro bubble water on the growth and morphology of three leaf lettuce cultivars (Lactuca sativa L.) grown under two kinds of LED irradiation

ABSTRACT This study examined the effects of micro-bubble water and two types of light-emitting diode (LED) irradiation (blue and red-blue) on the growth and morphology of three lettuce cultivars (Lactuca sativa L.). The growth in the above-ground portions of the two cultivars was reduced by the use of micro-bubble water depending on the type of LED irradiation employed. In particular the leaf weight of ‘Fancy green’ cultivated for 21 days under red-blue LED was significantly lower when it was grown with air-pumped micro-bubble water. The leaf weight of ‘Fancy red’ cultivated under blue LED and ‘Red fire’ under red-blue LED irradiation was significantly greater when they were grown with micro-bubble water than when they were grown without micro-bubble water. These results show that the effect of micro-bubble water differed between the cultivars and the types of LED irradiation employed. Furthermore, the use of an air pump is recommended when the generation of micro-bubbles in water is very intermittent, as in this experiment.

Resource Allocation for Cooperative Transmission in Optical Wireless Cellular Networks With Illumination Requirements

Visible light communication (VLC) often suffers from line-of-sight path blockages and high levels of inter-cell interference. Thus, the analysis and design of cooperation techniques become crucial to address these key impairments. This paper studies the performance of different resource allocation schemes that are suitable for multi-cell cooperative transmission when tri- and tetra-chromatic light-emitting diodes (LEDs) and optical orthogonal frequency-division multiple access are utilized. Firstly, guidelines are derived for maintaining the same spatial distribution of the signal-to-interference-plus-noise ratio (SINR) in every sector of the multi-cell environment in case of stand-alone (non-cooperative) and cooperative transmission. Secondly, the possible resource allocation configurations for both stand-alone and cooperative transmission modes are identified for different LED types and available orthogonal resources (i.e., frequency sub-bands per color and sectors per cell). Finally, the data rate gain of the multiple resource allocation configurations are also analyzed, while verifying the illumination constraints. The obtained results confirm that the proper design of cooperative transmission configurations will be of paramount importance to provide reliable wireless link in ultra-dense VLC deployments.