Patent Description:
Luminescent nanostructures (NSs) such as quantum dots (QDs) represent a class of phosphors that have the ability to emit light at a single spectral peak with narrow line width, creating highly saturated colors. It is possible to tune the emission wavelength based on the size of the NSs. The NSs are used to produce a NS film that can be used as a color conversion (CC) layer (also referred to as a color down-conversion layer) in display devices (e.g., liquid crystal display (LCD) device, organic light emitting diode (OLED) display device). The use of a NS-based CC layer in emissive displays can improve the system efficiency by down-converting white light, blue light, or ultra-violet (UV) light to a light in the red and/or green wavelength region before the light passes through a color filter. The use of a NS-based CC layer can reduce loss of light energy due to filtering.

The NS-based CC layers typically have planar top surfaces from which light is emitted. And, since these layers typically have a higher refractive index relative to the medium into which the light is emitted, a significant amount of the light generated by the NSs is reflected back into the CC layers through total internal reflection. Even though the light may escape through the planar top surfaces after multiple total internal reflections, the delay in light emission caused by the total internal reflections can result in significant optical losses in the display devices. As such, one of the challenges in producing NS-based display devices is achieving high light extraction efficiency (e.g., greater than <NUM>%, <NUM>%, <NUM>%, or <NUM>%) for high external quantum efficiency of the NS-based display devices.

<CIT> discloses such a display device wherein the light extraction efficiency is improved by providing a nano-structure on the inner surface of the light output substrate of the display.

Further relevant prior art is disclosed in <CIT> and <CIT>.

The present disclosure provides example highly efficient NS-based display devices with light extraction layers for enhanced light extraction from NS-based CC layers. The present disclosure also provides example inexpensive methods for fabricating the same.

In some embodiments, the light extraction layer can be configured to provide directivity to light emitted from a NS-based CC layer of the NS-based display device and substantially reduce or prevent total internal reflection of the emitted light within the NS-based CC layer, thus increasing the light extraction efficiency (e.g., greater than <NUM>%, <NUM>%, <NUM>%, or <NUM>%) of the NS-based display device. The light extraction layer can substantially reduce or prevent the total internal reflection by providing a non-uniform interface between the NS-based CC layer and a medium into which the light from the NS-based CC layer can be emitted. The non-uniform interface is provided by nanostructured features of the light extraction layer. The nanostructured features can be transfer printed in a repeating, a non-repeating, and/or a random pattern on a substrate of the light extraction layer.

In some embodiments, the nanostructured features and/or the substrate of the light extraction layer can include a material similar to a matrix material of the NS-based CC layer to provide a better refractive index matching with the NS-based CC layer than the refractive index matching between the NS-based CC layer and the medium. The better refractive index matching can also substantially reduce or prevent total internal reflection of the emitted light within the NS-based CC layer. The present disclosure further provides various embodiments to improve display performance such as color gamut coverage of the NS-based display devices by substantially reducing or eliminating leakage of unwanted light through one or more pixels of the display devices.

According to the embodiments, a display device includes a backlight unit having a light source and a liquid crystal display (LCD) module. The LCD module includes a nanostructure-based color conversion (NS-based CC) layer and a light extraction layer. The NS-based CC layer is configured to receive a primary light, from the light source, having a first peak wavelength and to convert a portion of the primary light to emit a first portion of a secondary light having a second peak wavelength. The second peak wavelength is different from the first peak wavelength. The light extraction layer is optically coupled to the NS-based CC layer and is configured to prevent total internal reflection of a second portion of the secondary light. The light extraction layer comprises a substrate and patterned features with one or more dimension in nanometer scale disposed on the substrate, wherein the substrate is disposed between the NS-based CC layer and the patterned features, and wherein top surfaces of the patterned features face away from a top surface of the NS-based CC layer.

According to some embodiments, which are not according to the claims, a method of fabricating a display device includes forming first and second parts of a liquid crystal display (LCD) module, disposing the second part of the LCD module on the first part of the LCD module, and disposing a display screen on the second part of the LCD module. The forming the first part includes disposing a liquid crystal solution layer on a back light unit (BLU) of the display device and disposing a polarizing filter on the liquid crystal solution layer. The forming the second part includes forming a light extraction layer on an optically transparent substrate and forming a nanostructure-based color conversion (NS-based CC) layer on the light extraction layer.

Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only.

The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present embodiments and, together with the description, further serve to explain the principles of the present embodiments and to enable a person skilled in the relevant art(s) to make and use the present embodiments.

Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.

Although specific configurations and arrangements may be discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the pertinent art will recognize that other configurations and arrangements can be used without departing from the scope of the present invention, which is defined by the appended claims. It will be apparent to a person skilled in the pertinent art that this invention can also be employed in a variety of other applications beyond those specifically mentioned herein. It should be appreciated that the particular implementations shown and described herein are examples and are not intended to otherwise limit the scope of the application in any way.

It is noted that references in the specification to "one embodiment," "an embodiment," "an example embodiment," etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Further, when a particular feature, structure or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to effect such feature, structure or characteristic in connection with other embodiments whether or not explicitly described.

All numbers in this description indicating amounts, ratios of materials, physical properties of materials, and/or use are to be understood as modified by the word "about," except as otherwise explicitly indicated.

In some embodiments, the term "display device" refers to an arrangement of elements that allow for the visible representation of data on a display screen. Suitable display screens can include various flat, curved or otherwise-shaped screens, films, sheets or other structures for displaying information visually to a user. Display devices described herein can be included in, for example, display systems encompassing a liquid crystal display (LCD), televisions, computers, mobile phones, smart phones, personal digital assistants (PDAs), gaming devices, electronic reading devices, digital cameras, tablets, wearable devices, car navigation systems, and the like.

The term "about" as used herein indicates the value of a given quantity varies by ±<NUM>% of the value. For example, "about <NUM>" encompasses a range of sizes from <NUM> to <NUM>, inclusive.

The term "substantially" as used herein indicates the value of a given quantity varies by ±<NUM>% to ±<NUM>% of the value.

In some embodiments, the term "forming a reaction mixture" or "forming a mixture" refers to combining at least two components in a container under conditions suitable for the components to react with one another and form a third component.

In some embodiments, the terms "light guide plate," "light guide," and "light guide panel" are used interchangeably and refer to an optical component that is suitable for directing electromagnetic radiation (light) from one position to another.

In some embodiments, the term "optically coupled" means that components are positioned such that light is able to pass from one component to another component without substantial interference.

The term "nanostructure" as used herein refers to a structure having at least one region or characteristic dimension with a dimension of less than about <NUM>. In some embodiments, the nanostructure has a dimension of less than about <NUM>, less than about <NUM>, less than about <NUM>, less than about <NUM>, or less than about <NUM>. Typically, the region or characteristic dimension will be along the smallest axis of the structure. Examples of such structures include nanowires, nanorods, nanotubes, branched nanostructures, nanotetrapods, tripods, bipods, nanocrystals, nanodots, QDs, nanoparticles, and the like. Nanostructures can be, e.g., substantially crystalline, substantially monocrystalline, polycrystalline, amorphous, or a combination thereof. In some embodiments, each of the three dimensions of the nanostructure has a dimension of less than about <NUM>, less than about <NUM>, less than about <NUM>, less than about <NUM>, less than about <NUM>, or less than about <NUM>.

The term "QD" or "nanocrystal" as used herein refers to nanostructures that are substantially monocrystalline. A nanocrystal has at least one region or characteristic dimension with a dimension of less than about <NUM>, and down to the order of less than about <NUM>. The terms "nanocrystal," "QD," "nanodot," and "dot," are readily understood by the ordinarily skilled artisan to represent like structures and are used herein interchangeably. The present invention also encompasses the use of polycrystalline or amorphous nanocrystals.

The term "heterostructure" when used with reference to nanostructures refers to nanostructures characterized by at least two different and/or distinguishable material types. Typically, one region of the nanostructure comprises a first material type, while a second region of the nanostructure comprises a second material type. In certain embodiments, the nanostructure comprises a core of a first material and at least one shell of a second (or third etc.) material, where the different material types are distributed radially about the long axis of a nanowire, a long axis of an arm of a branched nanowire, or the center of a nanocrystal, for example. A shell can but need not completely cover the adjacent materials to be considered a shell or for the nanostructure to be considered a heterostructure; for example, a nanocrystal characterized by a core of one material covered with small islands of a second material is a heterostructure. In other embodiments, the different material types are distributed at different locations within the nanostructure; e.g., along the major (long) axis of a nanowire or along a long axis of arm of a branched nanowire. Different regions within a heterostructure can comprise entirely different materials, or the different regions can comprise a base material (e.g., silicon) having different dopants or different concentrations of the same dopant.

As used herein, the term "diameter" of a nanostructure refers to the diameter of a cross-section normal to a first axis of the nanostructure, where the first axis has the greatest difference in length with respect to the second and third axes (the second and third axes are the two axes whose lengths most nearly equal each other). The first axis is not necessarily the longest axis of the nanostructure; e.g., for a disk-shaped nanostructure, the cross-section would be a substantially circular cross-section normal to the short longitudinal axis of the disk. Where the cross-section is not circular, the diameter is the average of the major and minor axes of that cross-section. For an elongated or high aspect ratio nanostructure, such as a nanowire, the diameter is measured across a cross-section perpendicular to the longest axis of the nanowire. For a spherical nanostructure, the diameter is measured from one side to the other through the center of the sphere.

The terms "crystalline" or "substantially crystalline," when used with respect to nanostructures, refer to the fact that the nanostructures typically exhibit long-range ordering across one or more dimensions of the structure. It will be understood by one of skill in the art that the term "long range ordering" will depend on the absolute size of the specific nanostructures, as ordering for a single crystal cannot extend beyond the boundaries of the crystal. In this case, "long-range ordering" will mean substantial order across at least the majority of the dimension of the nanostructure. In some instances, a nanostructure can bear an oxide or other coating, or can be comprised of a core and at least one shell. In such instances it will be appreciated that the oxide, shell(s), or other coating can but need not exhibit such ordering (e.g. it can be amorphous, polycrystalline, or otherwise). In such instances, the phrase "crystalline," "substantially crystalline," "substantially monocrystalline," or "monocrystalline" refers to the central core of the nanostructure (excluding the coating layers or shells). The terms "crystalline" or "substantially crystalline" as used herein are intended to also encompass structures comprising various defects, stacking faults, atomic substitutions, and the like, as long as the structure exhibits substantial long range ordering (e.g., order over at least about <NUM>% of the length of at least one axis of the nanostructure or its core). In addition, it will be appreciated that the interface between a core and the outside of a nanostructure or between a core and an adjacent shell or between a shell and a second adjacent shell can contain non-crystalline regions and can even be amorphous. This does not prevent the nanostructure from being crystalline or substantially crystalline as defined herein.

The term "monocrystalline" when used with respect to a nanostructure indicates that the nanostructure is substantially crystalline and comprises substantially a single crystal. When used with respect to a nanostructure heterostructure comprising a core and one or more shells, "monocrystalline" indicates that the core is substantially crystalline and comprises substantially a single crystal.

The term "ligand" as used herein refers to a molecule capable of interacting (whether weakly or strongly) with one or more faces of a nanostructure, e.g., through covalent, ionic, van der Waals, or other molecular interactions with the surface of the nanostructure.

The term "quantum yield" (QY) as used herein refers to the ratio of photons emitted to photons absorbed, e.g., by a nanostructure or population of nanostructures. As known in the art, quantum yield is typically determined by a comparative method using well-characterized standard samples with known quantum yield values.

The term "primary emission peak wavelength" as used herein refers to the wavelength at which the emission spectrum exhibits the highest intensity.

The term "full width at half-maximum" (FWHM) as used herein refers to refers to a measure of spectral width. In the case of an emission spectrum, a FWHM can refer to a width of the emission spectrum at half of a peak intensity value.

The term Forster radius used herein is also referred as Forster distance in the art.

The terms "luminance" and "brightness" are used herein interchangeably and refer to a photometric measure of a luminous intensity per unit area of a light source or an illuminated surface.

The terms "specular reflectors," "specularly reflective surfaces," and "reflective surfaces" are used herein to refer to elements, materials, and/or surfaces capable of specular reflection.

The term "specular reflection" is used herein to refer to a mirror-like reflection of light (or of other kinds of wave) from a surface, when an incident light hits the surface.

The term "nanostructure (NS) film" is used herein to refer to a film having luminescent nanostructures.

The term "red sub-pixel" is used herein to refer to an area of a pixel that emits light having a primary emission peak wavelength in the red wavelength region of the visible spectrum. In some embodiments, the red wavelength region can include wavelengths ranging from about <NUM> to about <NUM>.

The term "green sub-pixel" is used herein to refer to an area of a pixel that emits light having a primary emission peak wavelength in the green wavelength region of the visible spectrum. In some embodiments, the green wavelength region can include wavelengths ranging from about <NUM> to about <NUM>.

The term "blue sub-pixel" is used herein to refer to an area of a pixel that emits light having a primary emission peak wavelength in the blue wavelength region of the visible spectrum. In some embodiments, the blue wavelength region can include wavelengths ranging from about <NUM> to about <NUM>.

The term "emissive surface of a sub-pixel" is used herein to refer to a surface of a topmost layer of the sub-pixel from which light is emitted towards a display screen of a display device.

Any conflict between an art-understood definition of a word or phrase and a definition of the word or phrase as specifically taught in this specification shall be resolved in favor of the latter.

Technical and scientific terms used herein have the meaning commonly understood by one of skill in the art to which the present application pertains, unless otherwise defined. Reference is made herein to various methodologies and materials known to those of skill in the art.

<FIG> illustrates a schematic of an exploded cross-sectional view of an LCD display device <NUM> with a light extraction layer <NUM>, according to some embodiments. The view of display device in <FIG> is shown for illustration purposes and may not be drawn to scale. LCD display device <NUM> includes a backlight unit (BLU) <NUM> and an LCD module <NUM>, according to the embodiments.

BLU <NUM> can include an optical cavity <NUM> and an array of LEDs <NUM> (e.g., white LEDs, blue LEDs, or a combination thereof) coupled to optical cavity <NUM>. Optical cavity <NUM> can include a top side <NUM>, a bottom side <NUM>, sidewalls <NUM>, and a closed volume confined by top side <NUM>, bottom side <NUM>, and sidewalls <NUM>. LEDs <NUM> can be coupled to a top surface 105a of bottom side <NUM> within the closed volume. LEDs <NUM> can be configured to provide a primary light (e.g., a blue light, or a white light) that can be processed through LCD module <NUM> and subsequently, transmitted to and distributed across a display screen <NUM> of LCD display device <NUM>. In some embodiments, LEDs <NUM> can comprise blue LEDs that emit in the range from about <NUM> to about <NUM>. In some embodiments, LEDs <NUM> can comprise white LEDs that emit in the range from about <NUM> to about <NUM> or other possible light wavelength ranges. In some embodiments, the array of LEDs <NUM> can comprise a two-dimensional array of LEDs that are spread across an area of top surface 105a and the area can be equal to the surface area of display screen <NUM>.

It should be noted that even though two sidewalls <NUM> are shown in <FIG>, optical cavity <NUM> can include any number of sidewalls <NUM>, according to various embodiments. For example, optical cavity <NUM> can have a cuboid shape and can include four sidewalls similar to sidewalls <NUM>. Optical cavity <NUM> is not restricted to being cuboid in shape or having other straight-sided shapes. Optical cavity <NUM> can be configured to be any type of geometric shape, such as but not limited to cylindrical, trapezoidal, spherical, or elliptical, according to various embodiments, without departing from the scope of the present invention. It should also be noted that the rectangular cross-sectional shape of optical cavity <NUM>, as illustrated in <FIG>, is for illustrative purposes, and is not limiting. Optical cavity <NUM> can have other cross-sectional shapes (e.g., trapezoid, oblong, rhomboid), according to various embodiments, without departing from the scope of the present invention.

Top side <NUM> of optical cavity <NUM> can be configured to be an optically diffusive and transmissive layer such that light from LEDs <NUM> can exit optical cavity <NUM> through top side <NUM> with a substantially uniform distribution of brightness across top surface 103a of top side <NUM>. In some embodiments, top side <NUM> can include optically transparent areas and optically translucent areas that are strategically arranged over LEDs <NUM> to provide the substantially uniform distribution in light brightness exiting top side <NUM>. In another embodiment, top side <NUM> can include pores of varying sizes in diameters and optically translucent areas that are strategically arranged to provide the substantially uniform distribution in light brightness exiting top side <NUM>.

Bottom side <NUM> and/or sidewalls <NUM> can be constructed from one or more materials (e.g., metals, non-metals, and/or alloys) that are configured to have specularly reflective top surface 105a and/or specularly reflective side wall interior surfaces 107a, respectively. For example, top surface 105a and/or side wall interior surfaces 107a can be mirror-like surfaces having mirror-like reflection properties. In some embodiments, top surface 105a and/or side wall interior surfaces 107a can be completely specularly reflective or partially specularly reflective and partially scattering. In some other embodiments, top surface 105a and/or side wall interior surfaces 107a include diffuse reflectors.

In alternate embodiments, optical cavity <NUM> can include specular reflectors <NUM> coupled to sidewall interior surfaces 107a. Specular reflectors <NUM> can be coupled to sidewall interior surfaces 107a using optically transparent adhesive. The optically transparent adhesive can comprise tape, various glues, polymeric compositions such as silicones, etc. Additional optically transparent adhesive can include various polymers, including, but not limited to, poly(vinyl butyral), poly(vinyl acetate), epoxies, and urethanes; silicone and derivatives of silicone, including, but not limited to, polyphenylmethylsiloxane, polyphenylalkylsiloxane, polydiphenylsiloxane, polydialkylsiloxane, fluorinated silicones and vinyl and hydride substituted silicones; acrylic polymers and copolymers formed from monomers including, but not limited to, methylmethacrylate, butylmethacrylate, and laurylmethacrylate; styrene based polymers; and polymers that are cross linked with difunctional monomers, such as divinylbenzene, according to various examples.

Specularly reflective top surface 105a and side wall interior surfaces 107a and specular reflectors <NUM> can substantially minimize absorption of light from LEDs <NUM> through bottom side <NUM> and/or side walls <NUM> and thus, substantially minimize loss of luminance within optical cavity <NUM> and increase light output efficiency of BLU <NUM>.

In alternate embodiments, BLU <NUM> can further include one or more brightness enhancement films (BEFs) (not shown) disposed between optical cavity <NUM> and LCD module <NUM>. The one or more BEFs can have reflective and/or refractive films, reflective polarizer films, light extraction features, light recycling features, prism films, groove films, grooved prism films, prisms, pitches, grooves, or other suitable brightness enhancement features. The brightness-enhancing features of BEFs can be configured to reflect a portion of the primary light (e.g., blue light from optical cavity <NUM>) back toward optical cavity <NUM>, thereby providing recycling of the primary light.

LCD module <NUM> can be configured to process the light received from BLU <NUM> to desired characteristics for transmission to and distribution across display screen <NUM>. In some embodiments, LCD module <NUM> can include one or more polarizing filters, such as first and second polarizing filters <NUM> and <NUM>, one or more optically transparent substrates such as first and second optically transparent substrates <NUM> and <NUM>, switching devices <NUM> through <NUM> arranged in a <NUM>-D array on first substrate <NUM>, a liquid crystal (LC) solution layer <NUM>, a plurality of pixels such as pixels <NUM>-<NUM> arranged in a <NUM>-D array, a light extraction layer <NUM> disposed between pixels <NUM>-<NUM> and optically transparent substrate <NUM>, and display screen <NUM>.

In some embodiments, pixel <NUM> can include sub-pixels <NUM> through <NUM> and pixel <NUM> can include sub-pixels <NUM> through <NUM>. In some embodiments, each of pixels <NUM>-<NUM> can be tri-chromatic, for example, having red sub-pixels <NUM> and <NUM>, green sub-pixels <NUM> and <NUM>, and blue sub-pixels <NUM> and <NUM>, respectively.

The arrangement order of red, green, and blue sub-pixels <NUM> through <NUM> in respective pixels <NUM>-<NUM> is illustrative and is not limiting. The red, green, and blue sub-pixels in each of pixels <NUM>-<NUM> can be arranged in any order with respect to each other. In some embodiments, pixels <NUM> and/or <NUM> can be monochromatic having either red, green, or blue sub-pixels <NUM> through <NUM>. The number of pixels and switching devices shown in <FIG> are illustrative and are not limiting. LCD module <NUM> can have any number of switching devices and pixels without departing from the scope of this disclosure.

Light from BLU <NUM> can be polarized through first polarizing filter <NUM> and the polarized light can be transmitted to LC solution layer <NUM>. LC solution layer <NUM> can include LCs <NUM> having rod-shaped molecules that can act as shutters to control the amount of light transmission from LC solution layer <NUM>. In some embodiments, LCs <NUM> can be arranged in a <NUM>-D array. Columns <NUM> through <NUM> of the <NUM>-D array of LCs can be independently controlled by respective switching devices <NUM> through <NUM>. In some embodiments, switching devices <NUM> through <NUM> can comprise transistors, such as, for example, thin film transistors (TFTs). By controlling LCs <NUM>, the amount of light travelling from columns <NUM> through <NUM> to respective sub-pixels <NUM> through <NUM> can be controlled, and consequently, the amount of light transmitting from sub-pixels <NUM> through <NUM> is controlled.

LCs <NUM> can be twisted to varying degrees depending on the voltage applied to columns <NUM> through <NUM> by respective switching devices <NUM> through <NUM>. By controlling the twisting of LCs <NUM>, the polarization angle of light passing through LC solution layer <NUM> can be controlled. Light leaving LC solution layer <NUM> can then pass through second polarizing filter <NUM> that can be positioned at <NUM> degrees with respect to first polarizing filter <NUM>. The angle of polarization of the light leaving LC solution layer <NUM> and entering second polarizing filter <NUM> can determine how much of the light is able to pass through and exit from second polarizing filter <NUM>. Second polarizing filter <NUM> can attenuate the light, block the light, or allow the light to pass without attenuation based on its angle of polarization.

Portions of light travelling through columns <NUM> through <NUM> of LCs and exiting out of second polarizing filter <NUM> can then enter respective ones of sub-pixels <NUM> through <NUM>. These portions of light can undergo a stage of color filtering through the respective ones of sub-pixels <NUM> through <NUM> to achieve the desired optical characteristics for light distribution across display screen <NUM>. In some embodiments, each of sub-pixels <NUM> through <NUM> can include a NS-based CC layer <NUM> that can filter the portions of light entering sub-pixels <NUM> through <NUM>.

NS-based CC layers <NUM> can include luminescent nanostructures such as QDs (e.g., QD <NUM> described with reference to <FIG>), according to some embodiments. NS-based CC layers <NUM> can be down-converters, where the portions of light (also referred as primary light) entering the respective ones of sub-pixels <NUM> through <NUM> can be absorbed, for example, by the luminescent nanostructures in NS-based CC layers <NUM> and re-emitted as secondary light having a lower energy or longer wavelength than the primary light.

In some embodiments, NS-based CC layers <NUM> of red sub-pixels <NUM> and <NUM> can include luminescent nanostructures that absorb the primary light and emit a first secondary light having a primary emission peak wavelength in the red wavelength region of the visible spectrum light. In some embodiments, NS-based CC layers <NUM> of green sub-pixels <NUM> and <NUM> can include luminescent nanostructures that absorb the primary light and emit a second secondary light having a primary emission peak wavelength in the green wavelength region of the visible spectrum light. In some embodiments, NS-based CC layers <NUM> of blue sub-pixels <NUM> and <NUM> can include luminescent nanostructures that absorb the primary light and emit a third secondary light having a primary emission peak wavelength in the blue wavelength region of the visible spectrum light.

In alternate embodiments, blue sub-pixels <NUM> and <NUM> can have non-NS-based layers instead of NS-based CC layers <NUM>. The non-NS-based layers can exclude luminescent nanostructures such as QDs and can be optically transmissive to blue light when BLU <NUM> has blue LEDs <NUM>, as there is no need for down-conversion of primary light from blue LEDs <NUM> for blue sub-pixels <NUM> and <NUM>. In such alternate embodiments, instead of light blocking elements <NUM>, blue sub-pixels <NUM> and <NUM> can also have non-NS-based layers that are optically transmissive to blue light.

In some embodiments, NS-based CC layers <NUM> can be segmented films that are disposed adjacent to each other on second polarizing filter <NUM> or on an optically transparent substrate (not shown). The segmented NS-based CC layers <NUM> can be placed in a manner such that there is negligible gap at interfaces between adjacent NS-based CC layers <NUM> to prevent leakage of primary light through the interfaces. In alternate embodiments, each of NS-based CC layers <NUM> can be different regions of a continuous NS-based CC layer.

Optionally, each of sub-pixels <NUM> through <NUM> can include a light blocking element <NUM> disposed on NS-based CC layer <NUM>, according to some embodiments. The secondary light emitting from NS-based CC layers <NUM> can be filtered through corresponding ones of light blocking elements <NUM> before travelling to display screen <NUM>.

Light blocking elements <NUM> can be configured to allow the secondary light (e.g., first, second, and/or third secondary light discussed above) to pass and to block portions of the primary light (e.g., blue light) that are not absorbed by NS-based CC layers <NUM> and down-converted to the secondary light. The unwanted portions of primary light that may have leaked out of NS-based CC layers <NUM> can be blocked by absorbing and/or scattering them. Leakage of the unconverted primary light from NS-based CC layers <NUM> to display screen <NUM> can adversely affect the color gamut coverage of LCD display device <NUM>. The use of light blocking elements <NUM> to prevent such leakage can also help to reduce the manufacturing cost of LCD display device <NUM> by reducing the density of luminescent nanostructures included in NS-based CC layers <NUM>. The density of luminescent nanostructures can be reduced as instead of using the luminescent nanostructures to absorb substantially all portions of the primary light, any portions of primary light not absorbed in NS-based CC layers <NUM> can be filtered out by light blocking elements <NUM>.

Light blocking elements <NUM> can be also configured to tune the spectral emission widths (also referred as width of emission spectrum) of the secondary light (e.g., first, second, and/or third secondary light discussed above) to achieve a desired color gamut coverage of LCD display device <NUM>. Tuning of the spectral emission widths can require absorbing one or more wavelengths from the secondary light to narrow their spectral emission widths to achieve the desired color gamut coverage without significant decrease in brightness. For example, there can be less than <NUM>% (e.g., about <NUM>%, about <NUM>%, about <NUM>%, or about <NUM>%) decrease in brightness due to this tuning process compared to display devices without light blocking elements <NUM>. As the secondary light from NS-based CC layers <NUM> having luminescent nanostructures such as QDs typically exhibit narrow spectral emission widths, the tuning process may not require absorption of wide range of wavelengths to achieve the desired color gamut coverage as required in non-QD based display devices to achieve similar color gamut coverage.

Light blocking elements <NUM> can include one or more non-phosphor materials. That is, the one or more non-phosphor materials exhibit optical absorption properties and/or optical scattering properties, but do not exhibit optical emission properties. The one or more non-phosphor materials can be selected based on their optical absorption properties to absorb and/or on their scattering properties to scatter only the one or more wavelengths or range of wavelengths that require absorbing and/or scattering during the above described blocking and tuning processes. In some embodiments, the one or more non-phosphor materials can include the same absorption property. In some embodiment, each of the one or more non-phosphor materials includes an absorption property different from each other.

The one or more non-phosphor materials can be selected such that they can be inexpensively disposed on NS-based CC layers <NUM> or any other layer/structure (e.g., light extraction layer <NUM>) of LCD display device <NUM> to form light blocking elements <NUM>. For example, the one or more non-phosphor materials can be dye (e.g., narrow band organic Exciton P491 dye), ink, paint, polymeric material, an/or any material that can be sprayed, painted, spin-coated, printed, or any other suitable low temperature (e.g., below <NUM>) deposition method. Printing can be done using, for example, a plotter, an inkjet printer, or a screen printer. In some embodiments, the one or more non-phosphor materials can be directly disposed on NS-based CC layers <NUM> or on light extraction layer <NUM>. In some embodiments, the one or more non-phosphor materials can be scattering materials that include films or particles (e.g., particles having diameters ranging from about <NUM> to about <NUM>) of titanium oxide, zinc oxide, zinc sulfide, silicone, or a combination thereof. In some embodiments, light blocking elements <NUM> can include a substrate having the one or more non-phosphor materials disposed on it.

In some embodiments, light blocking elements <NUM> can be segmented films that are placed adjacent to each other on NS-based CC layers <NUM> or on light extraction layer <NUM>. The segmented light blocking elements <NUM> can be placed in a manner such that there is negligible gap at interfaces between adjacent light blocking elements <NUM>. In alternate embodiments, each of light blocking elements <NUM> can be different regions of a continuous film placed on NS-based CC layers <NUM> or on light extraction layer <NUM>.

In some embodiments, light blocking elements <NUM> may not be a separate structure as shown in <FIG>, but can be included in NS-based CC layers <NUM>. That is, NS-based CC layers <NUM> can be a composite film comprising the luminescent nanostructures, as described above, along with light blocking elements <NUM>. The one or more non-phosphor materials of light blocking elements <NUM> such as dye, ink, paint, polymeric material, scattering materials (e.g., particles having diameters ranging from about <NUM> to about <NUM>), or a combination thereof can be incorporated or embedded in a matrix of NS-based CC layers <NUM>. The one or more non-phosphor materials can include nanostructured materials that can be dispersed in a matrix of NS-based CC layers <NUM>. These nanostructured materials can exhibit optical absorption properties and/or optical scattering properties and may not exhibit any optical emission properties. In some embodiments, light blocking elements <NUM> can be included in optically transparent substrate <NUM>, which can also be configured to provide environmental sealing to the underlying layers and/or structures of LCD module <NUM> and/or BLU <NUM>. In alternate embodiments, light blocking elements <NUM> can be included in second polarizing filter <NUM>, which can be positioned between substrate <NUM> and NS-based CC layers <NUM>. In some embodiments, light blocking elements <NUM> can be dichroic filters that, for example, can reflect the primary light (e.g., blue light) while transmitting the secondary light.

In some embodiments, light extraction layer <NUM> can be disposed on surface 128a of substrate <NUM>. Light extraction layer <NUM> includes, according to the claimed invention, an optically transparent substrate <NUM> and nanostructured features <NUM> disposed on substrate <NUM>. In some embodiments, which are not according to the claims, light extraction layer <NUM> may not include substrate <NUM> and can have nanostructured features <NUM> formed directly on surface 128a. Nanostructured features <NUM> can be formed on substrate <NUM> or surface 128a using a transfer printing method. In some embodiments, nanostructured features <NUM> can be arranged in a repeating pattern, a random pattern, or a combination thereof on substrate <NUM> or surface 128a. In some embodiments, nanostructured features <NUM> can be arranged to form a corrugated surface on substrate <NUM> or surface 128a. The corrugated surface can be formed with an array of <NUM>-dimensional (e.g., strip-like), <NUM>-dimensional (e.g., pillar-like), and/or <NUM>-dimensional (e.g., sphere-like) nanostructured features <NUM>. Nanostructured features <NUM> can have any <NUM>-dimensional geometric shape (e.g., spherical, conical, cylindrical, cuboid, ellipsoidal, or trapezoidal). The lateral dimension of nanostructured features <NUM> along an X-axis (e.g., width) can be less than about <NUM> or can range from about <NUM> to about <NUM> (e.g., about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>). The vertical dimension of nanostructured features <NUM> along a Z-axis (e.g., height) can be less than about <NUM> or can range from about <NUM> to about <NUM> (e.g., about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>). The arrangement and shape of nanostructured features <NUM> in <FIG> are illustrative and are not limiting.

Light extraction layer <NUM> with its nanostructured features <NUM> can provide a non-uniform interface between substrate <NUM> and light blocking elements <NUM> or NS-based CC layers <NUM> when light blocking elements <NUM> are optionally absent. The non-uniform interface can substantially reduce or prevent the light generated by NS-based CC layers <NUM> and/or emitted by light blocking elements <NUM> from being reflected back into NS-based CC layers <NUM> due to total internal reflection of the emitted or generated light within respective light blocking elements <NUM> or NS-based CC layers <NUM>. As a result, light extraction layer <NUM> with its nanostructured features <NUM> can significantly increase the amount of light extracted from NS-based CC layers <NUM> and output from NS-based display device <NUM> compared to display devices without light extraction layer <NUM>.

In some embodiments, substrate <NUM> and/or nanostructured features <NUM> can include a material similar to a matrix material of NS-based CC layers <NUM> (e.g., matrix material <NUM> as described in <FIG>) to provide a better refractive index matching with NS-based CC layers <NUM> than the refractive index matching between NS-based CC layers <NUM> and substrate <NUM>. That is because, typically the matrix material of NS-based CC layers <NUM> has a higher refractive index than substrate <NUM> and if light in a higher refractive index material (e.g., NS-based CC layers <NUM>) encounters an interface with a lower refractive index material (e.g., substrate <NUM>) at an angle larger than the critical angle, then instead of passing out of the higher refractive index material, the light can be bent back into the higher refractive index material. This can be referred to as total internal reflection. Thus, the better refractive index matching can also substantially reduce or prevent total internal reflection of the emitted or generated light within respective light blocking elements <NUM> or NS-based CC layers <NUM>.

Display screen <NUM> can be configured to generate images. Display screen <NUM> can be a touch screen display, according to some embodiments. LCD display device <NUM> can further include one or more medium materials (not shown) disposed between any of the adjacent elements in LCD display device <NUM>, for example between optical cavity <NUM> and LCD module <NUM>, on either sides of LC solution layer <NUM>, or between any other elements of LCD display device <NUM>. The one or more medium materials can include, but not limited to, substrates, a vacuum, air, gas, optical materials, adhesives, optical adhesives, glass, polymers, solids, liquids, gels, cured materials, optical coupling materials, index-matching or index-mismatching materials, index-gradient materials, cladding or anti-cladding materials, spacers, epoxy, silica gel, silicones, brightness-enhancing materials, scattering or diffuser materials, reflective or anti-reflective materials, wavelength-selective materials, wavelength-selective anti-reflective materials, or other suitable medium material. Suitable materials can include silicones, silicone gels, silica gel, epoxies (e.g., Loctite™ Epoxy E-30CL), acrylates (e.g., <NUM>™ Adhesive <NUM>). The one or more medium materials can be applied as a curable gel or liquid and cured during or after deposition, or pre-formed and pre-cured prior to deposition. Curing methods can include UV curing, thermal curing, chemical curing, or other suitable curing methods known in the art. Index-matching medium materials can be chosen to minimize optical losses between elements of BLU <NUM> and LCD module <NUM>.

LCD display device <NUM> can have a geometric shape, such as but not limited to cylindrical, trapezoidal, spherical, or elliptical, according to various embodiments, without departing from the scope of the present invention. LCD display device <NUM> is not restricted to being cuboid in shape or having other straight-sided shapes. It should be noted that the rectangular cross-sectional shape of LCD display device <NUM> is for illustrative purposes, and is not limiting. LCD display device <NUM> can have other cross-sectional shapes (e.g., trapezoid, oblong, rhomboid), according to various embodiments, without departing from the scope of the present invention. It should also be noted that even though optical cavity <NUM>, substrates <NUM> and <NUM>, polarizing filter <NUM> and <NUM>, and display screen <NUM> are shown in <FIG> to have similar dimensions along X-axis, a person skilled in the art would understand that each of these components can have dimensions different from each other in one or more directions, according to various embodiments.

<FIG> illustrates a schematic of an exploded cross-sectional view of an edge-lit LCD display device <NUM> with a light extraction layer <NUM>, according to some embodiments. LCD display device <NUM> includes a BLU <NUM> and LCD module <NUM>. Elements in <FIG> with the same annotations as elements in <FIG> are described above.

BLU <NUM> can include an LED <NUM> (e.g., a blue LED), a light guide plate (LGP) <NUM>, and a reflector <NUM>. BLU <NUM> can be configured to provide a primary light (e.g., a blue light) that can be processed through LCD module <NUM> and subsequently, transmitted to and distributed across display screen <NUM>. The blue LED can emit in the range from about <NUM> to about <NUM>. According to some embodiments, the blue LED can be, for example, a GaN LED that emits blue light at a wavelength of <NUM>.

LGP <NUM> can include fiber optic cables, polymeric or glass solid bodies such as plates, films, containers, or other structures, according to some embodiments. The size of LGP <NUM> can depend on the ultimate application and characteristics of LED <NUM>. The thickness of LGP <NUM> can be compatible with thickness of LED <NUM>. The other dimensions of LGP <NUM> can be designed to extend beyond the dimensions of LED <NUM>, and can be on the order of <NUM>'s of millimeters, to <NUM>'s to <NUM>'s of centimeters.

In some embodiments, the materials of LGP <NUM> can include polycarbonate (PC), poly methyl methacrylate (PMMA), methyl methacrylate, styrene, acrylic polymer resin, glass, or other suitable LGP materials. Suitable manufacturing methods for LGP <NUM> can include injection molding, extrusion, or other suitable embodiments. LGP <NUM> can be configured to provide uniform primary light emission, such that primary light entering LCD module <NUM> can be of uniform color and brightness. LGP <NUM> can include a substantially uniform thickness over the entire LGP <NUM> surface. Alternatively, LGP <NUM> can have a wedge-like shape. In some embodiments, LGP <NUM> can be optically coupled to LED <NUM> and can be physically connected to or detached from LED <NUM>. For physically connecting LGP <NUM> to LED <NUM>, optically transparent adhesive can be used (not shown).

In some embodiments, BLU <NUM> can include an array of LEDs (not shown), each of which can be similar to LED <NUM> in structure and function. The array of LEDs can be adjacent to LGP <NUM> and can be configured to provide the primary light to LCD module <NUM> for processing and for subsequent transmission to display screen <NUM> as discussed above with reference to <FIG>.

In some embodiments, reflector <NUM> can be configured to increase the amount of light that is emitted from LGP <NUM>. Reflector <NUM> can comprise a suitable material, such as a reflective mirror, a film of reflector particles, a reflective metal film, or other suitable conventional reflectors. In some embodiments, reflector <NUM> can include a white film. In some embodiments, reflector <NUM> can include additional functionality or features, such as scattering, diffuser, or brightness-enhancing features.

<FIG> is a flow diagram of an example method <NUM> for fabricating display devices <NUM> and/or <NUM>. Steps can be performed in a different order or not performed depending on specific applications. It should be noted that method <NUM> may not produce a complete display device. Accordingly, it is understood that additional processes can be provided before, during, and after method <NUM>, and that some other processes may only be briefly described herein.

In step <NUM>, a BLU with one or more light sources is formed. For example, as described with reference to <FIG>, BLU <NUM> can be formed with optical cavity <NUM> and array of LEDs <NUM> (e.g., white LEDs, blue LEDs, or a combination thereof) coupled to optical cavity <NUM> or BLU <NUM> can be formed with LGP <NUM> and LED <NUM> (e.g., a blue LED).

In step <NUM>, switching devices, LC solution layer, and polarizing filter are disposed on the BLU. For example, as described with reference to <FIG>, switching devices <NUM> through <NUM> arranged in a <NUM>-D array can be disposed optically transparent substrate <NUM>, which is disposed on BLU <NUM> or <NUM>, LC solution layer <NUM> can be disposed on switching devices <NUM> through <NUM>, and polarizing filter <NUM> can be disposed on LC solution layer <NUM>.

In step <NUM>, a light extraction layer is formed on an optically transparent substrate. For example, as described with reference to <FIG>, light extraction layer <NUM> including substrate <NUM> and nanostructured features <NUM> can be formed on substrate <NUM>. In some embodiments, which are not according to the claims, nanostructured features <NUM> of light extraction layer <NUM> can be formed directly on substrate <NUM>. Nanostructured features <NUM> can be formed using a transfer printing method.

In step <NUM>, light blocking elements and/or NS-based CC layers are formed on the light extraction layer. For example, as described with reference to <FIG>, light blocking elements <NUM> can be disposed on light extraction layer <NUM> by spraying, painting, spin-coating, printing, or any other suitable low temperature (e.g., below <NUM>) deposition method. Printing can be done using, for example, a plotter, an inkjet printer, or a screen printer. NS-based CC layers <NUM> can be disposed on light blocking elements <NUM> by a suitable deposition method (e.g., method described for forming NS film in <FIG>). In some embodiments, NS-based CC layers <NUM> can be disposed directly on light extraction layer <NUM> when light blocking elements <NUM> are optionally absent.

In step <NUM>, the substrate with the light extraction layer <NUM>, the light blocking elements, and the NS-based CC layers are disposed on the polarizing filter. For example, as described with reference to <FIG>, substrate <NUM> with light extraction layer <NUM>, light blocking elements <NUM>, and NS-based CC layers <NUM> can be disposed on polarizing filter <NUM> with NS-based layers <NUM> facing and in contact with polarizing filter <NUM>.

In step <NUM>, a display screen is disposed on the substrate. For example, as described with reference to <FIG>, display screen <NUM> can be disposed on a surface of substrate <NUM> that is opposite to surface 128a having light extraction layer <NUM>.

<FIG> illustrates a cross-sectional structure of a barrier layer coated luminescent nanostructure (NS) <NUM>, according to some embodiments. In some embodiments, a population of NS <NUM> can be included in NS-based CC layer <NUM>. Barrier layer coated NS <NUM> includes a NS <NUM> and a barrier layer <NUM>. NS <NUM> includes a core <NUM> and a shell <NUM>. Core <NUM> includes a semiconducting material that emits light upon absorption of higher energies. Examples of the semiconducting material for core <NUM> include indium phosphide (InP), cadmium selenide (CdSe), zinc sulfide (ZnS), lead sulfide (PbS), indium arsenide (InAs), indium gallium phosphide, (InGaP), cadmium zinc selenide (CdZnSe), zinc selenide (ZnSe) and cadmium telluride (CdTe). Any other II-VI, III-V, tertiary, or quaternary semiconductor structures that exhibit a direct band gap can be used as well. In some embodiments, core <NUM> can also include one or more dopants such as metals, alloys, to provide some examples. Examples of metal dopant can include, but not limited to, zinc (Zn), Copper (Cu), aluminum (Al), platinum (Pt), chrome (Cr), tungsten (W), palladium (Pd), or a combination thereof. The presence of one or more dopants in core <NUM> can improve structural and optical stability and QY of NS <NUM> compared to undoped NSs.

Core <NUM> can have a size of less than <NUM> in diameter, according to some embodiments. In another embodiment, core <NUM> can have a size between about <NUM> and about <NUM> in diameter. The ability to tailor the size of core <NUM>, and consequently the size of NS <NUM> in the nanometer range enables photoemission coverage in the entire optical spectrum. In general, the larger NSs emit light towards the red end of the spectrum, while smaller NSs emit light towards the blue end of the spectrum. This effect arises as larger NSs have energy levels that are more closely spaced than the smaller NSs. This allows the NS to absorb photons containing less energy, i.e. those closer to the red end of the spectrum.

Shell <NUM> surrounds core <NUM> and is disposed on outer surface of core <NUM>. Shell <NUM> can include cadmium sulfide (CdS), zinc cadmium sulfide (ZnCdS), zinc selenide sulfide (ZnSeS), and zinc sulfide (ZnS). In some embodiments, shell <NUM> can have a thickness 404t, for example, one or more monolayers. In other embodiments, shell <NUM> can have a thickness 404t between about <NUM> and about <NUM>. Shell <NUM> can be utilized to help reduce the lattice mismatch with core <NUM> and improve the QY of NS <NUM>. Shell <NUM> can also help to passivate and remove surface trap states, such as dangling bonds, on core <NUM> to increase QY of NS <NUM>. The presence of surface trap states can provide non-radiative recombination centers and contribute to lowered emission efficiency of NS <NUM>.

In alternate embodiments, NS <NUM> can include a second shell disposed on shell <NUM>, or more than two shells surrounding core <NUM>, without departing from the scope of the present invention. In some embodiments, the second shell can be on the order of two monolayers thick and is typically, though not required, also a semiconducting material. Second shell can provide protection to core <NUM>. Second shell material can be zinc sulfide (ZnS), although other materials can be used as well without deviating from the scope of the invention.

Barrier layer <NUM> is configured to form a coating on NS <NUM>. In some embodiments, barrier layer <NUM> is disposed on and in substantial contact with outer surface 404a of shell <NUM>. In embodiments of NS <NUM> having one or more shells, barrier layer <NUM> can be disposed on and in substantial contact with the outermost shell of NS <NUM>. In an example embodiment, barrier layer <NUM> is configured to act as a spacer between NS <NUM> and one or more NSs in, for example, a solution, a composition, and/or a film having a plurality of NSs, where the plurality of NSs can be similar to NS <NUM> and/or barrier layer coated NS <NUM>. In such NS solutions, NS compositions, and/or NS films, barrier layer <NUM> can help to prevent aggregation of NS <NUM> with adjacent NSs. Aggregation of NS <NUM> with adjacent NSs can lead to increase in size of NS <NUM> and consequent reduction or quenching in the optical emission properties of the aggregated NS (not shown) including NS <NUM>. In further embodiments, barrier layer <NUM> provides protection to NS <NUM> from, for example, moisture, air, and/or harsh environments (e.g., high temperatures and chemicals used during lithographic processing of NSs and/or during manufacturing process of NS based devices) that can adversely affect the structural and optical properties of NS <NUM>.

Barrier layer <NUM> includes one or more materials that are amorphous, optically transparent and/or electrically inactive. Suitable barrier layers include inorganic materials, such as, but not limited to, inorganic oxides and/or nitrides. Examples of materials for barrier layer <NUM> include oxides and/or nitrides of Al, Ba, Ca, Mg, Ni, Si, Ti, or Zr, according to various embodiments. Barrier layer <NUM> can have a thickness 406t ranging from about <NUM> to about <NUM> in various embodiments.

As illustrated in <FIG>, barrier layer coated NS <NUM> can additionally or optionally include a plurality of ligands or surfactants <NUM>, according to some embodiments. Ligands or surfactants <NUM> can be adsorbed or bound to an outer surface of barrier layer coated NS <NUM>, such as on an outer surface of barrier layer <NUM>, according to some embodiments. The plurality of ligands or surfactants <NUM> can include hydrophilic or polar heads 408a and hydrophobic or non-polar tails 408b. The hydrophilic or polar heads 408a can be bound to barrier layer <NUM>. The presence of ligands or surfactants <NUM> can help to separate NS <NUM> and/or NS <NUM> from other NSs in, for example, a solution, a composition, and/or a film during their formation. If the NSs are allowed to aggregate during their formation, the quantum efficiency of NSs such as NS <NUM> and/or NS <NUM> can drop. Ligands or surfactants <NUM> can also be used to impart certain properties to barrier layer coated NS <NUM>, such as hydrophobicity to provide miscibility in non-polar solvents, or to provide reaction sites (e.g., reverse micellar systems) for other compounds to bind.

A wide variety of ligands exist that can be used as ligands <NUM>. In some embodiments, the ligand is a fatty acid selected from lauric acid, caproic acid, myristic acid, palmitic acid, stearic acid, and oleic acid. In some embodiments, the ligand is an organic phosphine or an organic phosphine oxide selected from trioctylphosphine oxide (TOPO), trioctylphosphine (TOP), diphenylphosphine (DPP), triphenylphosphine oxide, and tributylphosphine oxide. In some embodiments, the ligand is an amine selected from dodecylamine, oleylamine, hexadecylamine, and octadecylamine. In some embodiments, the ligand is trioctylphosphine (TOP). In some embodiments, the ligand is oleylamine. In some embodiments, the ligand is diphenylphosphine.

A wide variety of surfactants exist that can be used as surfactants <NUM>. Nonionic surfactants can be used as surfactants <NUM> in some embodiments. Some examples of nonionic surfactants include polyoxyethylene (<NUM>) nonylphenylether (commercial name IGEPAL CO-<NUM>), polyoxyethylene (<NUM>) nonylphenylether (IGEPAL CO-<NUM>), octylphenoxy poly(ethyleneoxy)ethanol (IGEPAL CA-<NUM>), polyethylene glycol oleyl ether (Brij <NUM>), polyethylene glycol hexadecyl ether (Brij <NUM>), polyethylene glycol octadecyl ether (Brij S10), polyoxyethylene (<NUM>) isooctylcyclohexyl ether (Triton X-<NUM>), and polyoxyethylene branched nonylcyclohexyl ether (Triton N-<NUM>).

Anionic surfactants can be used as surfactants <NUM> in some embodiments. Some examples of anionic surfactants include sodium dioctyl sulfosuccinate, sodium stearate, sodium lauryl sulfate, sodium monododecyl phosphate, sodium dodecylbenzenesulfonate, and sodium myristyl sulfate.

In some embodiments, NSs <NUM> and/or <NUM> can be synthesized to emit light in one or more various color ranges, such as red, orange, and/or yellow range. In some embodiments, NSs <NUM> and/or <NUM> can be synthesized to emit light in the green and/or yellow range. In some embodiments, NSs <NUM> and/or <NUM> can be synthesized emit light in the blue, indigo, violet, and/or ultra-violet range. In some embodiments, NSs <NUM> and/or <NUM> can be synthesized to have a primary emission peak wavelength between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>.

NSs <NUM> and/or <NUM> can be synthesized to display a high QY. In some embodiments, NSs <NUM> and/or <NUM> can be synthesized to display a QY between <NUM>% and <NUM>% or between <NUM>% and <NUM>%.

Thus, according to various embodiments, NSs <NUM> can be synthesized such that the presence of barrier layer <NUM> on NSs <NUM> does not substantially change or quench the optical emission properties of NSs <NUM>.

<FIG> illustrates a cross-sectional view of a NS film <NUM>, according to some embodiments. In some embodiments, NS-based CC layer <NUM> can be similar to NS film <NUM>.

NS film <NUM> can include a plurality of barrier layer coated core-shell NSs <NUM> (<FIG>) and a matrix material <NUM>, according to some embodiments. NSs <NUM> can be embedded or otherwise disposed in matrix material <NUM>, according to some embodiments. As used herein, the term "embedded" is used to indicate that the NSs are enclosed or encased within matrix material <NUM> that makes up the majority component of the matrix. It should be noted that NSs <NUM> can be uniformly distributed throughout matrix material <NUM> in some embodiments, though in other embodiments NSs <NUM> can be distributed according to an application-specific uniformity distribution function. It should be noted that even though NSs <NUM> are shown to have the same size in diameter, a person skilled in the art would understand that NSs <NUM> can have a size distribution.

In some embodiments, NSs <NUM> can include a homogenous population of NSs having sizes that emit in the blue visible wavelength spectrum, in the green visible wavelength spectrum, or in the red visible wavelength spectrum. In other embodiments, NSs <NUM> can include a first population of NSs having sizes that emit in the blue visible wavelength spectrum, a second population of NSs having sizes that emit in the green visible wavelength spectrum, and a third population of NSs that emit in the red visible wavelength spectrum.

Matrix material <NUM> can be any suitable host matrix material capable of housing NSs <NUM>. Suitable matrix materials can be chemically and optically compatible with NSs <NUM> and any surrounding packaging materials or layers used in applying NS film <NUM> to devices. Suitable matrix materials can include non-yellowing optical materials which are transparent to both the primary and secondary light, thereby allowing for both primary and secondary light to transmit through the matrix material. In some embodiments, matrix material <NUM> can completely surround each of the NSs <NUM>. The matrix material <NUM> can be flexible in applications where a flexible or moldable NS film <NUM> is desired. Alternatively, matrix material <NUM> can include a high-strength, non-flexible material.

Matrix material <NUM> can include polymers and organic and inorganic oxides. Suitable polymers for use in matrix material <NUM> can be any polymer known to the ordinarily skilled artisan that can be used for such a purpose. The polymer can be substantially translucent or substantially transparent. Matrix material <NUM> can include, but not limited to, epoxies, acrylates, norbornene, polyethylene, poly(vinyl butyral):poly(vinyl acetate), polyurea, polyurethanes; silicones and silicone derivatives including, but not limited to, amino silicone (AMS), polyphenylmethylsiloxane, polyphenylalkylsiloxane, polydiphenylsiloxane, polydialkylsiloxane, silsesquioxanes, fluorinated silicones, and vinyl and hydride substituted silicones; acrylic polymers and copolymers formed from monomers including, but not limited to, methylmethacrylate, butylmethacrylate, and laurylmethacrylate; styrene-based polymers such as polystyrene, amino polystyrene (APS), and poly(acrylonitrile ethylene styrene) (AES); polymers that are crosslinked with bifunctional monomers, such as divinylbenzene; cross-linkers suitable for cross-linking ligand materials, epoxides which combine with ligand amines (e.g., APS or PEI ligand amines) to form epoxy, and the like.

In some embodiments, matrix material <NUM> includes scattering microbeads such as TiO<NUM> microbeads, ZnS microbeads, or glass microbeads that can improve photo conversion efficiency of NS film <NUM>. In some embodiments, matrix material <NUM> can include light blocking elements such as light blocking elements <NUM> described above with reference to <FIG>.

In another embodiment, matrix material <NUM> can have low oxygen and moisture permeability, exhibit high photo- and chemical-stability, exhibit favorable refractive indices, and adhere to outer surfaces of NSs <NUM>, thus providing an air-tight seal to protect NSs <NUM>. In another embodiment, matrix material <NUM> can be curable with UV or thermal curing methods to facilitate roll-to-roll processing.

According to some embodiments, NS film <NUM> can be formed by mixing NSs <NUM> in a polymer (e.g., photoresist) and casting the NS-polymer mixture on a substrate, mixing NSs <NUM> with monomers and polymerizing them together, mixing NSs <NUM> in a sol-gel to form an oxide, or any other method known to those skilled in the art.

According to some embodiments, the formation of NS film <NUM> can include a film extrusion process. The film extrusion process can include forming a homogenous mixture of matrix material <NUM> and barrier layer coated core-shell NSs such as NS <NUM>, introducing the homogenous mixture into a top mounted hopper that feeds into an extruder. In some embodiments, the homogenous mixture can be in the form of pellets. The film extrusion process can further include extruding NS film <NUM> from a slot die and passing extruded NS film <NUM> through chill rolls. In some embodiments, the extruded NS film <NUM> can have a thickness less than about <NUM>, for example, in a range from about <NUM> to about <NUM> , from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, or form about <NUM> to about <NUM>. In some embodiments, NS film <NUM> has a thickness less than <NUM>. In some embodiments, the formation of NS film <NUM> can optionally include a secondary process followed by the film extrusion process. The secondary process can include a process such as co-extrusion, thermoforming, vacuum forming, plasma treatment, molding, and/or embossing to provide a texture to a top surface of NS film <NUM>. The textured top surface NS film <NUM> can help to improve, for example defined optical diffusion property and/or defined angular optical emission property of NS film <NUM>.

Described herein are various compositions having luminescent nanostructures (NSs). The various properties of the luminescent nanostructures, including their absorption properties, emission properties and refractive index properties, can be tailored and adjusted for various applications.

The material properties of NSs can be substantially homogenous, or in certain embodiments, can be heterogeneous. The optical properties of NSs can be determined by their particle size, chemical or surface composition. The ability to tailor the luminescent NS size in the range between about <NUM> and about <NUM> can enable photoemission coverage in the entire optical spectrum to offer great versatility in color rendering. Particle encapsulation can offer robustness against chemical and UV deteriorating agents.

Luminescent NSs, for use in embodiments described herein can be produced using any method known to those skilled in the art. Suitable methods and example nanocrystals are disclosed in <CIT>; <CIT>; <CIT>; and <CIT>.

Luminescent NSs for use in embodiments described herein can be produced from any suitable material, including an inorganic material, and more suitably an inorganic conductive or semiconductive material. Suitable semiconductor materials can include those disclosed in <CIT>, and can include any type of semiconductor, including group II-VI, group III-V, group IV-VI and group IV semiconductors. Suitable semiconductor materials can include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SuS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si<NUM>N<NUM>, Ge<NUM>N<NUM>, Al<NUM>O<NUM>, (Al, Ga, In)<NUM> (S, Se, Te)<NUM>, Al<NUM>CO, and an appropriate combination of two or more such semiconductors.

In certain embodiments, the luminescent NSs can have a dopant from the group consisting of a p-type dopant or an n-type dopant. The NSs can also have II-VI or III-V semiconductors. Examples of II-VI or III-V semiconductor NSs can include any combination of an element from Group II, such as Zn, Cd and Hg, with any element from Group VI, such as S, Se, Te and Po, of the Periodic Table; and any combination of an element from Group III, such as B, Al, Ga, In, and Tl, with any element from Group V, such as N, P, As, Sb and Bi, of the Periodic Table.

The luminescent NSs, described herein can also further include ligands conjugated, cooperated, associated or attached to their surface. Suitable ligands can include any group known to those skilled in the art, including those disclosed in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>. Use of such ligands can enhance the ability of the luminescent NSs to incorporate into various solvents and matrixes, including polymers. Increasing the miscibility (i.e., the ability to be mixed without separation) of the luminescent NSs in various solvents and matrixes can allow them to be distributed throughout a polymeric composition such that the NSs do not aggregate together and therefore do not scatter light. Such ligands are described as "miscibility-enhancing" ligands herein.

In certain embodiments, compositions having luminescent NSs distributed or embedded in a matrix material are provided. Suitable matrix materials can be any material known to the ordinarily skilled artisan, including polymetic materials, organic and inorganic oxides. Compositions described herein can be layers, encapsulants, coatings, sheets or films. It should be understood that in embodiments described herein where reference is made to a layer, polymeric layer, matrix, sheet or film, these terms are used interchangeably, and the embodiment so described is not limited to any one type of composition, but encompasses any matrix material or layer described herein or known in the art.

Down-converting NSs (for example, as disclosed in <CIT>) utilize the emission properties of luminescent nanostructures that are tailored to absorb light of a particular wavelength and then emit at a second wavelength, thereby providing enhanced performance and efficiency of active sources (e.g., LEDs).

While any method known to the ordinarily skilled artisan can be used to create luminescent NSs, a solution-phase colloidal method for controlled growth of inorganic nanomaterial phosphors can be used. See <NPL>); <NPL>); and <NPL>).

According to some embodiments, CdSe can be used as the NS material, in one example, for visible light down-conversion, due to the relative maturity of the synthesis of this material. Due to the use of a generic surface chemistry, it can also possible to substitute non-cadmium-containing NSs.

In semiconductor NSs, photo-induced emission arises from the band edge states of the NS. The band-edge emission from luminescent NSs competes with radiative and non-radiative decay channels originating from surface electronic states. As a result, the presence of surface defects such as dangling bonds provide non-radiative recombination centers and contribute to lowered emission efficiency. An efficient and permanent method to passivate and remove the surface trap states can be to epitaxially grow an inorganic shell material on the surface of the NS. The shell material can be chosen such that the electronic levels are type <NUM> with respect to the core material (e.g., with a larger bandgap to provide a potential step localizing the electron and hole to the core). As a result, the probability of non-radiative recombination can be reduced.

Core-shell structures can be obtained by adding organometallic precursors containing the shell materials to a reaction mixture containing the core NSs. In this case, rather than a nucleation event followed by growth, the cores act as the nuclei, and the shells can grow from their surface. The temperature of the reaction is kept low to favor the addition of shell material monomers to the core surface, while preventing independent nucleation of nanocrystals of the shell materials. Surfactants in the reaction mixture are present to direct the controlled growth of shell material and to ensure solubility. A uniform and epitaxially grown shell can be obtained when there is a low lattice mismatch between the two materials.

Example materials for preparing core-shell luminescent NSs can include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, Co, Au, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTc, BeS, BcSe, BcTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuP, CuCl, CuBr, CuI, Si<NUM>N<NUM>, Ge<NUM>N<NUM>, Al<NUM>O<NUM>, (Al, Ga, In)<NUM> (S, Se, Te)<NUM>, AlCO, and shell luminescent NSs for use in the practice of the present invention include, but are not limited to, (represented as Core/Shell), CdSe/ZnS, InP/ZnS, InP/ZnSe, PbSe/PbS, CdSe/CdS, CdTe/CdS, CdTe/ZnS, as well as others.

Luminescent NSs for use in the embodiments described herein can be less than about <NUM> in size, and down to less than about <NUM> in size and invention absorb visible light. As used herein, visible light is electromagnetic radiation with wavelengths between about <NUM> and about <NUM> nanometers that is visible to the human eye. Visible light can be separated into the various colors of the spectrum, such as red, orange, yellow, green, blue, indigo and violet. Blue light can comprise light between about <NUM> and about <NUM>, green light can comprise light between about <NUM> and <NUM> and red light can comprise light between about <NUM> and about <NUM> in wavelength.

According to various embodiments, the luminescent NSs can have a size and a composition such that they absorb photons that are in the ultraviolet, near-infrared, and/or infrared spectra. The ultraviolet spectrum can comprise light between about <NUM> to about <NUM>, the near-infrared spectrum can comprise light between about <NUM> to about <NUM> in wavelength, and the infrared spectrum can comprise light between about <NUM> to about <NUM> in wavelength.

While luminescent NSs of other suitable material can be used in the various embodiments described herein, in certain embodiments, the NSs can be ZnS, InAs, CdSe, or any combination thereof to form a population of nanocrystals for use in the embodiments described herein. As discussed above, in further embodiments, the luminescent NSs can be core/shell nanocrystals, such as CdSe/ZnS, InP/ZnSe, CdSe/CdS or InP/ZnS.

Suitable luminescent nanostructures, methods of preparing luminescent nanostructures, including the addition of various solubility-enhancing ligands, can be found in Published <CIT>.

Claim 1:
A display device comprising:
a backlight unit comprising a light source; and
a liquid crystal display (LCD) module comprising:
a nanostructure-based color conversion (NS-based CC) layer configured to receive a primary light, from the light source, having a first peak wavelength and to convert a portion of the primary light to emit a first portion of a secondary light having a second peak wavelength that is different from the first peak wavelength; and
a light extraction layer, optically coupled to the NS-based CC layer, configured to prevent total internal reflection of a second portion of the secondary light, wherein the light extraction layer comprises a substrate and patterned features with one or more dimension in nanometer scale disposed on the substrate,
characterised in that
the substrate is disposed between the NS-based CC layer and the patterned features, and wherein top surfaces of the patterned features face away from a top surface of the NS-based CC layer.