High power LED lamp is the main component of the LED lighting source, high power led is restricted by heat, light efficiency, in recent years LED developed very slowly. This year with the development of cooling technology, the package technology improvement ,high power LED lamp has a rapid development, becomes one of the main light source.
Integrated current injection efficiency, radio-luminescence quantum efficiency, light extraction efficiency of the outside of the chip, and finally only about 30-40% of the input electric energy can be turned into light energy, the rest of the 60-70% energy is mainly converted to heat energy by lattice vibration from non- radiative -recombination occurring in the form of the conversion of heat.
While the chip temperature increases, it will enhance non-radiative--recombination, and further weaken the luminous efficiency. Because people subjectively think no heat from large power LED, in fact there is a lot of heat, so that the problems take place in the use of the process. Moreover a lot of people first use high-power LED, they don't understand and how to effectively solve the heat problem and then make the reliability of products have become a major problem. Then, LED whether there is heat generation? How much heat can LED produce .
LED in the forward voltage, the electron gains energy from the power supply, under the electric drive, LED overcomes the PN junction electric field, jump from N to the P zone, these electron recombination with vacancies in P zone. And as the free electron drifts to P region, whose energy is higher than that of P valence electrons. when recombining ,the electron is back to low energy state, the excess energy is emitted in the form of a photon . a photon wavelength by emitting is relative to and the energy difference of Eg. Visibly, light region is mainly located near the PN junction , the luminescence is due to the energy release by recombining electron and vacancies. A semiconductor diode, electron will encounter the resistance during the process from going into the semiconductor region to all walk away from the semiconductor region. Simply from the theory, the physical structure of semiconductor diode simply from the theory, the physical structure source’s cathode of semiconductor diode sends the same numbers of electrons with those which returns to anode semiconductor. Common diode ,in the event of the recombination of electron -hole pairs , due to the factors of energy difference Eg . the photon spectra by releasing is in no visible range.
LED heat production has nothing to do with the light effect; it doesn’t exist a few percent of the electric power generating light, the other a few percent of the electric power generating heat . Through the analysis of LED heat generation; thermal resistance; junction temperature and measurement of thermal resistance of high power, understanding of the concept and the formula derivation. We can do research on the actual packaging design of high power LED, evaluation and product application need to note is the thermal management is a key issue in the LED luminous efficiency which is not high at the present stage, Fundamentally, we need to improve the luminous efficiency to reduce heat generation, which is a fundamental solution, so we need to improve each link’s technology like the chip manufacturing, packaging and application and development of LED products.
LED light source is solid green light, energy saving advantages are obvious, especially under the background of the national energy-saving and emission reduction policies, LED has becomes strategic industry driven by the government, enterprises investment ,LED lighting will gradually be extended, and may gradually replace other lighting source.