Pixelligent Glossary

Your A-Z glossary for key terms used throughout the Pixelligent site.


a* is the color component that measures the range of red-green (with negative values for green and positive values for red.)

Abbe number

Abbe number is an indicator of chromatic dispersion, or the wavelength dependence of a material’s refractive index. Materials with high refractive index and low chromatic aberration are valuable to optical components such as lenses, prisms, waveguides, diffraction gratings, and more.


Additives are substances added to various materials like coatings or paints in small quantities to improve performance under certain conditions. Additives can include Photoinitiators (or Thermoinitiators), Surfactants, Antioxidants, and Inhibitors.

Anatase Crystalline Structure

Anatase is one of the several polymorphs of titanium dioxide (TiO2) with a tetragonal crystal structure. It is meta-stable and converts to a rutile structure at high temperatures. Anatase TiO2 occurs naturally as a mineral and can be prepared synthetically. It is a wide-band semiconductor (3.2eV) and is also widely used as a photocatalyst.


Antioxidants are additives used to prevent or slow down the degradation of materials caused by oxidative reactions. They are commonly added to polymers, plastics, and coatings to improve their stability and lifespan by inhibiting the formation of free radicals.

AR (Augmented Reality)

Augmented reality (AR) refers to technology that overlays digital information, like images, graphics, or data, on your real-world environment in real-time. Users experience a blend of the physical and virtual worlds through AR-enabled devices, such as smartphones or AR glasses. This interactive and immersive experience enhances perception, offering additional context, details, or interactive elements to the real-world surroundings. AR applications range from gaming and entertainment to industrial training, navigation, and educational purposes.

Anti-Reflective Coating

An anti-reflective coating is a thin layer applied to optical surfaces to reduce unwanted reflections by minimizing the amount of light that bounces off, thus enhancing visibility and image quality.


b* is the color component that measures the range of yellow-blue.

Base Formulation

Pixelligent’s base formulations are composed of the PixClear Titania or Zirconia nanoparticle plus a monomer, with or without a solvent. These formulations are intended as a starting point for final formulations that also contain a resin, such as PixNIL or PixJet.

Capping agent

A capping agent is an organic ligand covalently bonded to the surface of a nanoparticle. These agents help to prevent nanoparticle agglomeration and promotes compatibility with host solvent and polymer to make clear nanocomposites.



The CIELAB color space, also referred to as L*a*b*, is a color space defined by the International Commission on Illumination (abbreviated CIE). It expresses color as three values: L* for perceptual lightness and a* and b* for the four unique colors of human vision: red, green, blue and yellow.

Coating techniques

Coating techniques are methods used to apply a thin layer of material onto a substrate surface for various purposes, such as protection, decoration, functionalization, or altering surface properties. There are numerous coating techniques available, each with its own advantages. Pixelligent materials are mostly compatible with spin coating, inkjet printing, and slot die coating techniques, among others. These techniques can be chosen based on factors like the type of substrate, desired coating material, thickness requirements, cost considerations, and specific properties needed for the coated surface.


Core-shell technology, also known as core-shell nanoparticles, involves the synthesis of nanoparticles with a unique design consisting of a central core surrounded by a shell or coating of a different material. The core and shell materials have distinct properties, and the combination allows for enhanced functionalities and improved performance compared to individual components. For Pixelligent, our PixCor core-shell synthesized nanoparticles are composed of titania surrounded by a shell of zirconia. This was developed to get the benefits of both nanocrystals; the refractive index of titania and the UV protection of zirconia.


A crosslinker is a chemical compound with two or more reactive groups that facilitates the formation of covalent bonds between polymer chains or other macromolecules. The process of forming these covalent bonds is called crosslinking or crosslinkage. When crosslinkers react with polymers, they create new connections or bridges between individual polymer chains. This results in the formation of a three-dimensional network structure, where the polymer chains are linked together, rather than existing as separate linear chains. The process of crosslinking enhances the mechanical, thermal, and chemical properties of the material and leads to improvements such as increased strength, stiffness, and dimensional stability. The choice of crosslinker and its concentration can significantly influence the properties of the resulting crosslinked material, making it an essential aspect of materials design and polymer science. Crosslinkers typically have a high viscosity (or could be solid at room temperature) and help to improve film mechanical properties and chemical resistance.

D99.99 or Dv(99.99)

The parameter D99.99 should more correctly be labeled as Dv(99.99). It signifies the point in the size distribution, up to and including which, 99.99% of the total volume of material in the sample is ‘contained’. For example, if the D99.99 is 500nm, this means that 99.99% of the sample has a size of 500nm or smaller.

Diffraction (Light diffraction)

Light diffraction is the bending and spreading of light waves as they pass through an aperture or encounter obstacles, causing interference patterns and altering the direction of light propagation.

DLS (Dynamic Light Scattering)

Dynamic Light Scattering (DLS) is a technique used to measure the size and movement of nanoparticles suspended or dispersed in liquid. It analyzes the fluctuations in scattered light intensity caused by the motion of the particles. DLS is widely applied in various fields, including nanotechnology, biophysics, and colloid science, providing valuable insights into particle size distributions and aggregation behaviors in solution.

DOE (Diffractive Optical Elements)

Diffractive Optical Elements (DOE) are specialized optical components that manipulate light waves using diffraction patterns engraved or etched onto their surfaces. These patterns act as microstructures, causing light to split, focus, shape, or distribute into complex intensity profiles. DOEs offer advantages over traditional refractive elements, enabling compact and lightweight optical systems with improved efficiency and functionality. They find applications in laser beam shaping, holography, 3D imaging, optical trapping, and various laser-based technologies, providing precise control and manipulation of light for diverse scientific, industrial, and technological purposes.

400-nm DOE features Courtesy of NIL Tech

Field of view (FoV)

Field of view (FoV) refers to the extent of the observable or visible area that can be seen through an optical instrument, such as a waveguide, microscope, telescope, camera, or human eye, at any given moment without moving the instrument or changing its position. The angular or linear measurement describes the width or height of the viewable area. A larger field of view allows one to see a broader area, providing a wider perspective, while a smaller field of view focuses on a narrower area, resulting in a more magnified and detailed view. PixClear products are designed specifically to increase FoV in XR waveguides and optics devices.

Final Formulation

Pixelligent’s final formulations are composed of a nanoparticle and a resin, either with or without a solvent. These include additives as well.


FTIR stands for “Fourier transform infrared,” and it is the most common form of infrared spectroscopy. All infrared spectroscopies act on the principle that when infrared (IR) radiation passes through a sample, some of the radiation is absorbed. The radiation that passes through the sample is recorded. Because different molecules with their different structures produce different spectra, the spectra can be used to identify and distinguish among molecules. In this way, the spectra are like people’s fingerprints or DNA: virtually unique.

Gradient Index Optics (Visible or Short-Wave Infrared Wavelengths)

Gradient index optics, also known as GRIN optics, involve materials with varying refractive indices within the optical element. Unlike conventional optics with uniform refractive indices, GRIN optics use a graded index profile to manipulate light. This results in lenses or fibers that can focus or collimate light without the need for complex shapes or surfaces. GRIN optics offer lightweight and compact optical components, reducing aberrations and enabling advanced imaging systems, fiber optics, and laser devices. These unique properties make them valuable in telecommunications, medical imaging, endoscopy, and various other optical applications.


Hardness refers to a measurement of a material’s resistance to localized plastic deformation caused by abrasion or indentation forces. For example, materials such as titania typically have higher hardness than standard plastics.


% Haze is a measure of the amount of light scattering or diffusion in a transparent material, causing a loss of clarity. It quantifies the degree of haziness, opaqueness, or cloudiness in the material, expressed as a percentage of transmitted light that deviates from a direct path.

Hydrodynamic Diameter

Hydrodynamic diameter is the diameter of a nanoparticle measured by DLS that measures the sphere of liquid that the particle displaces. It’s important to note that the measure of DLS will not equal TEM diameter measurement.


Index-matching is the process of matching the refractive index of two materials to reduce light reflection and improve optical transmission at their interface, minimizing loss and improving efficiency in optical devices such as lenses, displays, and XR devices.


An inhibitor is a substance added to a system or material to slow down or prevent certain chemical reactions from occurring. Inhibitors work by interfering with the reaction mechanism, reducing the rate of reaction or preventing it altogether. They are used to control undesirable reactions that could lead to degradation, corrosion, polymerization, or other unwanted changes in materials or processes. Inhibitors are commonly employed in various industries, such as chemical manufacturing, oil and gas, coatings, and more.

Inkjet print

Inkjet printing involves the use of a pressure-driven flow of a coating material through narrow nozzles. To ensure consistent droplet ejection and avoid clogging, an optimized coating formulation is required for this coating method. This deposition method offers several advantages, including material conservation. Pixelligent’s high refractive index PixJet formulations are compatible with industry-leading inkjet tools.

Internal Light Extraction (ILE) layer

An Internal Light Extraction (ILE) layer is a thin film or structure incorporated within optoelectronic devices, such as light-emitting diodes (LEDs) or OLEDs. Its purpose is to increase the efficiency of light extraction from the device’s active region by scattering or redirecting the light that would otherwise remain trapped due to total internal reflection. By improving light extraction, ILE layers enhance the device’s brightness, luminous efficiency, and overall performance, making them more energy-efficient and suitable for various applications, including displays, lighting, and XR technologies.


Infrared radiation (IR), also known as thermal radiation, is that band in the electromagnetic radiation spectrum with wavelengths above red visible light between 780 nm and 1 mm. IR is categorized as IR-A (780 nm-1.4 µm), IR-B (1.4-3 µm) and IR-C, also known as far-IR (3 µm-1 mm).


L* is a parameter that measures lightness or brightness of a material, especially in films, coatings, and similar applications.


LiDAR, which stands for Light Detection and Ranging, is a remote sensing technology that uses laser pulses to measure distances and create 3D representations of the Earth’s surface and detect objects. A LiDAR system emits laser beams, which bounce off objects and return to the sensor. By measuring the time it takes for the laser to return, the system calculates the distance to each object, producing highly detailed topographical maps, terrain models, and point clouds. LiDAR is widely used in applications such as surveying, cartography, autonomous vehicles, forestry, environmental monitoring, and archaeology.

Light outcoupling

Light outcoupling refers to the process of extracting light generated within a material or device, such as an OLED (organic light-emitting diode) device or display. Some light can become trapped in these devices due to total internal reflection. Light outcoupling techniques aim to enhance the efficiency of light extraction, allowing more light to escape the device and contribute to the desired application, such as displays or lighting, leading to improved overall performance, clarity, and brightness.

Light scattering

Light scattering is the way light behaves when it interacts with a medium that contains particles or the boundary between different mediums where defects or structures are present. Due to this interaction light incident on an ensemble of particles — crystals, aerosols, molecules, atoms etc. — is partially “deflected” in directions deviating from the incident direction. In some scattering processes, in addition to the change in direction, there is also a change in frequency. The evaluation of the scattered light with regard to its intensity and its wavelength often yields valuable information about the scattering matter.

Loading / Nanocrystal Loading

Nanocrystal loading refers to the process of incorporating nanocrystals, which are extremely small crystalline particles with dimensions typically in the nanometer range (1-100 nanometers), into a matrix or host material. The purpose of nanocrystal loading is to introduce unique properties and functionalities of nanocrystals into the bulk material, thereby enhancing its overall performance for various applications. Once embedded or dispersed within the host material, nanocrystals can influence its properties, thus improving mechanical strength, electrical conductivity, optical properties, or catalytic activity.


The Metaverse is a set of digital spaces, including immersive experiences, where users are networked, allowing them to move across different digital domains. It aims to revolutionize communication, entertainment, education, and commerce, creating a seamless integration of physical and virtual experiences, blurring the lines between the digital and real world.


A monomer is a small molecule composed of 1-2 reactive groups that has the capability to join with other monomers to form larger molecules called polymers. Monomers play a crucial role in the field of materials science and chemistry as they provide the building blocks for creating a wide range of polymers with distinct properties and applications.

MR (Mixed Reality)

Mixed reality (MR) is an advanced technology that combines elements of both augmented reality (AR) and virtual reality (VR) to create an immersive experience. MR seamlessly blends virtual objects with the real-world environment, allowing users to interact with and perceive both digital and physical elements simultaneously.


Nanocomposites are materials composed of a matrix (polymer, metal, or ceramic) infused with nanoparticles or nanofibers. These nanoparticles enhance the material’s properties, like strength, conductivity, or thermal resistance, making nanocomposites valuable in various industries, including optics, XR, display, and sensors.


A nanocrystal is a small crystal structure, typically on the nanometer scale, composed of atoms or molecules arranged in a well-defined lattice. These nanoscale crystals exhibit unique optical, electronic, and magnetic properties, making them valuable for various applications in nanotechnology and materials science.


A nanometer (nm) is a unit of length in the metric system. It is equal to one billionth of a meter, which means there are 1,000,000,000 (one billion) nanometers in a meter. Nanometers are commonly used to describe the scale of extremely small objects, such as molecules, nanoparticles, and nanoscale structures. In nanotechnology, the manipulation and study of materials at the nanoscale (typically ranging from about 1 to 100 nanometers) have led to the development of novel materials and applications with unique properties and functionalities, such as Pixelligent’s PixClear nanocomposites and PixNIL and PixJet formulations.

NIL (Nano-Imprint Lithography)

Nanoimprint lithography is a high-resolution nanofabrication technique used to create intricate patterns on a substrate. It involves pressing a mold containing the desired pattern into a thin layer of polymer on the substrate. The pattern is then transferred to the material by thermal or UV curing. This process allows for the production of nanoscale structures with precise control, making this technique valuable for various applications, such as optoelectronics, XR, and sensor devices.


An organic light-emitting diode (OLED), also known as an organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current. This organic layer is situated between two electrodes; typically, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, and portable systems such as smartphones and handheld game consoles.

Passivated Surface (or Passivation Layer)

A passivated surface is a treated metal surface with a thin, protective oxide layer formed through a chemical process to enhance corrosion resistance and prevent further chemical reactions with the environment.


Photocatalysis is a photo-activated chemical reaction occurring when free radical mechanisms are initiated as contact is made between the compound and photons that have sufficiently high energy levels.


Photoinitiators are molecules that absorb photons upon irradiation with light and form reactive species out of the excited state, which initiate consecutive reactions. The initiating species may be radicals, cations, or anions, which subsequently initiate polymerization.


Photolithography is a fabrication process used to pattern and transfer circuit designs onto silicon wafers. It involves applying a light-sensitive photoresist material on the wafer’s surface, exposing it to UV light through a mask with the desired pattern, and developing the exposed resist to create a template. This template is then used to etch or deposit materials, defining intricate microscale features in the semiconductor devices, enabling the creation of advanced microelectronics.

Planarizing layer

A planarizing layer is a thin film deposited on a non-flat substrate to create a smooth, level surface. It aims to eliminate irregularities that may arise during the nanofabrication process. Planarizing layers are commonly used in deposition processes like spin-coating. By filling in gaps and recesses, planarization improves the quality and reliability of subsequent layers. This even surface ensures uniform photolithography and etching, contributing to the precise patterning and manufacturing of intricate microelectronic devices, which reduces device defects and enhances performance.


QLED (Quantum-dot Light-Emitting Diode) is a display technology that incorporates quantum dots to enhance the color and brightness of an LED backlight in LCD panels. It provides a wide color gamut and improved picture quality compared to traditional LCD displays, offering vibrant and more accurate colors.

Quantum Dot

Quantum dot is a nanoscale semiconductor material with unique electronic properties. When exposed to light or electricity, quantum dots emit light of specific colors determined by their size. They find applications in displays, lighting, and biomedical imaging for their tunable and bright emission characteristics.

Refractive Index (RI)

Refractive index (also known as the index of refraction, or “n”), is an optical property that quantifies how much light bends or changes its direction when passing through a medium compared to its propagation in a vacuum. The refractive index determines how much light is bent when it enters or exits a medium, leading to phenomena like refraction, total internal reflection, and the formation of optical lenses. Different materials have distinct refractive indices, which influence how light interacts with them, impacting various optical applications and phenomena.


A resin is a type of semi-solid or viscous substance derived from a combination of monomers and crosslinkers. It can be used as an adhesive, coating, or molding material due to its ability to harden or cure into a solid state through chemical reactions, heat, or light (UV).

Rutile Crystalline Structure

Rutile is one of the two common polymorphs of TiO2, the other being Anatase, and the most stable phase thermodynamically. It exhibits excellent optical properties, making it widely used in pigments, coatings, and optical devices. Rutile’s unique crystal structure contributes to its high refractive index, leading to its efficient light scattering and reflection properties, which are valuable in applications like sunscreen, paints, and optical coatings.

Scatterer Particles

Scatterer particles are small substances or objects within a medium that cause light or other waves to deviate from their original path through scattering. They disperse the incident radiation in various directions, resulting in phenomena like diffused reflection or haze. Scatterer particles are essential in creating various optical effects in materials and natural phenomena. (See Light Scattering)

Sellmeier equation

The Sellmeier equation provides an approximation for the refractive index dispersion of certain glasses and other optical materials over a limited spectral range. It is often used in optical design and calculations related to light propagation, dispersion, and color characteristics of transparent media.

The general form of the Sellmeier equation for a material is:
n(λ) = √[1 + ∑(B_i * λ^2) / (λ^2 – C_i^2)]

Where n(λ) is the refractive index of the material at a given wavelength λ; B_i and C_i are coefficients specific to the material; and the summation is taken over all relevant i values for the material.

SEM – Scanning Electron Microscopy

A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample.

Shear Strength

Shear strength is the maximum resistance of a material to internal forces that cause it to deform or slide along parallel planes. It is a measure of a material’s structural integrity.

Shelf Life

Shelf-life refers to the period during which a product remains suitable for use, manipulation, or sale, maintaining its quality, safety, and efficacy.

Slot-die coating

Slot-die coating is a precise and continuous process in which a liquid or viscous material is deposited onto a substrate through a narrow slot, creating uniform thin films or coatings used in various applications, including electronics, solar cells, and flexible displays.


A solvent is a substance capable of dissolving other substances, forming a homogeneous mixture called a solution. Solvents are commonly used to dissolve solids, liquids, or gases, allowing for various chemical processes, cleaning, extraction, and formulation in industries like chemistry, manufacturing, and nanotechnology. Pixelligent utilizes solvents like ETA and PGMEA in our solvent-containing Designer Compounds and Designer Composites, though we also offer solvent-free formulations.


Spin-coating is a thin-film deposition technique in which a liquid solution or suspension is dispensed onto a flat substrate, which is then rapidly spun, causing the liquid to spread uniformly over the surface due to centrifugal force. After spinning, the solvent evaporates, leaving behind a thin, smooth, and uniform film, commonly used in microelectronics, optics, and nanotechnology.

Surfactants (Surface-Active Agents)

Surfactants, short for surface-active agents, are additives that modify the surface properties of materials by reducing surface tension or promoting the dispersion of particles. They are commonly used in paints, coatings, and inks to improve wetting and spreadability.

TEM – Transmission Electron Microscopy

Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a sensor such as a scintillator attached to a charge-coupled device.

Tg (Glass transition temperature)

Glass transition temperature (Tg) is the temperature at which an amorphous material, like glass, undergoes a reversible transition from a rigid, glassy state to a more flexible, rubbery state. It marks the boundary between the glassy and rubbery phases, affecting material properties and behavior.

TGA (Thermogravimetric Analysis)

Thermogravimetric refers to a technique used in materials analysis and research to measure the weight changes of a sample as it is subjected to controlled heating or cooling. In a thermogravimetric analysis (TGA), the sample’s weight is continuously monitored under programmed temperature conditions. This method allows researchers to study various processes like thermal stability, decomposition, oxidation, and moisture content of a material. For Pixelligent materials, we use it to measure loading and capping amounts for our nanocrystal dispersions.

Total internal reflection (TIR)

Total internal reflection occurs when light passes from a material with a high refractive index to one with a lower refractive index at a certain angle, it can no longer escape into the air and instead is reflected back into the material.

Transparency %T

Transparency (%T) is a measure of how much light is transmitted through a material. It represents the percentage of incident light that passes through the material without being absorbed or scattered, indicating the material’s clarity or degree of opaqueness.


Ultraviolet (UV) is a form of electromagnetic radiation with wavelength shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights such as mercury-vapor lamps and Xenon lamps. The UV region covers the wavelength range 100-400 nm and is divided into three bands: UVA (315-400 nm); UVB (280-315 nm); UVC (100-280 nm).


Viscosity is a measure of a fluid’s resistance to flow. It describes the internal friction of a moving fluid. A fluid with large viscosity resists motion because its molecular makeup gives it a lot of internal friction. A fluid with low viscosity flows easily because its molecular makeup results in very little friction when it is in motion.

Visible Spectrum

The visible light spectrum is the segment of the electromagnetic spectrum that the human eye can view. More simply, this range of wavelengths is called visible light. Typically, the human eye can detect wavelengths from 380 to 700 nanometers.

VR (Virtual Reality)

Virtual Reality (VR) is a computer-generated simulation that immerses users in a three-dimensional, interactive environment. Through specialized VR devices like headsets or goggles, users can explore and interact with the virtual world as if they were physically present, providing a highly immersive and realistic experience.


A waveguide, specifically for XR (Extended Reality) devices, is a specialized optical component that guides and directs light to the user’s eyes. It ensures the efficient transmission of augmented reality (AR) or virtual reality (VR) content, enabling more immersive experiences. By utilizing reflective or refractive surfaces, the waveguide overlays digital information onto the user’s view of the real world or generates virtual environments, enhancing the overall XR experience with minimal image distortion and improved visual clarity.

XR (Extended Reality)

Extended Reality (XR) is an umbrella term that encompasses virtual reality (VR), augmented reality (AR), and mixed reality (MR). It refers to technologies that merge the physical and virtual worlds, enabling users to interact with digital content and experiences in a more immersive and interactive manner.