■Applications
Semiconductor nanocrystals (quantum dots) can be utilized with traditional LEDs as a phosphor in order to create high quality white light or high purity specialty colors that span the spectrum from the UV, visible, through the infra-red. Nanocrystals can be used alone or in combination with other traditional rare-earth phosphors to best combine brightness, lonegivity, and color quality. Because of the flexibility in processing nanocrystals into a usable form, they can be deposited directly on top of the LED die, within the encapsulant material, or with the lens-cap, illuminaires or fixtures.

Nanocrystals (quantum dots) are single excitation source tunable light emitters that can be used to make efficient green, orange or other wavelengths where traditional LED dies and phosphors have low efficiency . They can be used as an additive to increase the Color Rendering Index (CRI) and produce warmer or cooler tones to white light for architectural lighting purposes or for certain medical applications.


Nanocrystals (quantum dots) can be combined with a variety of optical quality matrix materials including polymers, silicones, epoxies,sol-gels, oxides, etc. Evident Technologies has demonstrated stable nanocrystal composites compatible with spin- and dip-coating processes, ink-jetting, spraying and screen-printing deposition processes, commonly used in the OLED industry. Through these composite materials and processes, nanocrystals can be seamlessly implemented into current OLED products.

Today, fluorescent color arrays, known as color changing medium, are deposited or placed on top or blue OLED structures to create full color displays. Semiconductor nanocrystal composites can be used in a similar way either in conjunction with tradition color changing materials or as an outright replacement. Nanocrystal, can be synthesized to emit high quality light throughout the visible spectrum (as well as the UV and infrared) that be excited with underlying blue OLED emitters. Because they are inorganic and protected from degradation through surface engineering, they are stable, long lasting, and resistant to temperature degradation. Nanocrystals have a response time orders of magnitude greater than the frame rate time (on the order of 10s of nanoseconds), can be seen from a wide viewing angle, and do not suffer from differential aging because the emitted color is independent of the material system.

OLED displays may be improved, or color modified, by doping the emitter with semiconductor nanocrystals. They can be dispersed within the conducting polymers and light emitting polymers used in OLEDs and orPLEDs and are also compatible with small molecule emitters. It is also possible to dope nanocrystals directly within OLED device structures as a an intrinsic phosphor that is excited via adjacent electroluminescent centers. In this manner you can create high quality and efficient full color or white emission without adding subsequent manufacturing steps associated with the color change material layer used in traditional OLED devices.

Evident Technologies has demonstrated direct electroluminescent emission at visible wavelengths and at IR wavelengths important for optical telecommunications. The wavelength and the bandwidth of the emitted light was directly determined by the size and composition of the dispersed nanocrystals within the device. The company has expertise in modifying the nanocrystal surfaces with molecules that facilitate charge transport into the nanocrystals from the conducting matrixes.

Using nanocrystals (quantum dots), vibrant colors including blue and deep blues can be generated. Because of the inorganic nature of the particles, they are inherently stable and can increase the operational lifetimes of the ensuing devices.