A method for increasing the luminous intensity of an ultraviolet light emitting diode includes heating an ultraviolet light emitting diode to a working temperature, and supplying electricity to the ultraviolet light emitting diode at the working temperature to make the ultraviolet light emitting diode emit ultraviolet light. An apparatus for increasing the luminous intensity of an ultraviolet light emitting diode includes a substrate, an ultraviolet light emitting diode mounted on the substrate, an electric heater mounted on the substrate, a temperature sensor, and a controller electrically connected to the ultraviolet light emitting diode, the electric heater, and the temperature sensor. The controller can heat the ultraviolet light emitting diode through the substrate. When the temperature sensor detects that the temperature of the ultraviolet light emitting diode reaches a working temperature, the controller supplies electricity to the ultraviolet light emitting diode to make the ultraviolet light emitting diode emit ultraviolet light.

A nitride white-light LED includes: a substrate; an epitaxial layer; an N-type electrode and a P-type electrode; channels are formed on the substrate and the epitaxial layer; temperature isolation layers are formed with low thermal conductivity material thereon to form three independent temperature zones (Zones I/II/III) on a single chip; temperature control layers are formed with high thermal conductivity material on the side wall of the epitaxial layer and the back surface of the substrate at Zones I/II/III, and control temperature of the epitaxial layer and the substrate; based on different thermal expansion coefficients, lattice constants of the nitride and the substrate at Zones I/II/III are regulated to adjust the biaxial stress to which the nitride; quantum wells change conduction band bottom and valence band top positions to change forbidden band widths and light-emitting wavelengths; the LED can emit red, green and blue lights by a single chip.

Example superlattice structures and methods for thermoelectric devices are provided. An example structure may include a plurality of superlattice periods. Each superlattice period may include a first material layer disposed adjacent to a second material layer. For each superlattice period, the first material layer may be formed of a first material and the second material layer may be formed of a second material. The plurality of superlattice periods may include a first superlattice period and a second superlattice period. A thickness of a first material layer of the first superlattice period may be different than a thickness of a first material layer of the second superlattice period.

Certain embodiments are directed to a lighting device comprising one or more of the following: a plurality of LEDs; a plurality of optic devices corresponding to the plurality of LEDs; at least one optical separator for substantially preventing the light emitted from one LED from effecting the other LEDs; a thermoelectric device configured to harvest heat generated by the LEDs and convert the harvested heat into electrical energy; and a low temperature material for creating a temperature difference across the thermoelectric device.

An illumination system includes: a light-emitting module including a blue LED light source that emits blue light having a light emission peak in a blue range of from 400 nm to 470 nm and a red LED light source that emits red light having a light emission peak in a red range of from 610 nm to 680 nm; a light regulator that controls a first light intensity, which is light intensity at the light emission peak in the blue range, and a second light intensity, which is light intensity at the light emission peak in the red range, in a light emission spectrum of light emitted by the light-emitting module; and a clock that measures a time. The light regulator causes the second light intensity to change in conjunction with a change in the first light intensity, in accordance with the time measured by the clock.