It is the king of LED technology CSP component is not enough?

In 1981, a new concept of nanoscale semiconductor light-emitting particles was discovered, and we call it "Dot" (Quantum, QD). From the discovery to the previous 10 years, people also only in the academic point of view of its nature, and after a period of 10 years and basically did not find its application areas. After 2000, quantum dots preparation technology to improve the development of its application field, especially the spectral quantum dot technology with adjustable size, large Stokes shift, high luminous efficiency, good light stability and a series of unique optical properties has become the focus of research in recent years, and has made significant progress. At present, the quantum dot biotechnology first applied in medicine, quantum dot TV display has appeared, quantum dot LED (QLED) light source was born in the laboratory.

1 the next 15 years, quantum dot LED will light up the world

In 1879, the incandescent lamp finished the last step from the laboratory to the practical lighting, creating a new era of human electric lighting, only a short period of 20 years, the incandescent lamp ripped off the night, lit the world.

In 1938, the fluorescent lamp turned out, mankind entered the era of gas discharge lighting, 20 years later, the fluorescent lights will be lit every night thousands of households. In 1980, the emergence of three primary fluorescent lights will be brought into the era of decorative lighting. 20 years later, energy-saving lamps become the cheapest light source covered the world's 5 continents.

1998, the world's first practical white light LED came out, 15 years later, LED is beginning to take over the entire lighting market, LED lit up in twenty-first Century.

2009, the first quantum dot LED (QLED) light bulb was born in the United states. In 2010, the Chinese made a breakthrough in quantum dot technology, QLED lighting into a practical starting point.

Although expensive quantum dot material is now impossible to enter the field of mass lighting, but we have reason to believe: 15 years later in 2030, indoor lighting will become the world's QLED!

2 magical quantum dots: Incredible nanocrystals

Quantum dot is a kind of nano crystal. The composition is not limited to the II-VI group (BaS, CdTe) or III-V (GaAs, InGaAs) and now I - III - VI (AgInS2) of several elements, with the in-depth study, more system will be developed.

Most of the quantum dots are inorganic compounds, and their properties are stable and can be formed in water, which is between 1 and 20 nm in size, which is equivalent to the size of 5~100 atoms. The 3 dimensions of the quantum dot are below nm, and the quantum dot is a quasi zero dimensional nanomaterial (see figure 100) from the dimensions of the quantum dots (see Figure 1). We are particularly interested in the properties of the quantum dots, which are closely related to the excitation and luminescence properties, such as surface effect, quantum confinement effect and size effect.

Surface effect of 2.1 quantum dots

With the decrease of the number of atoms, the particle size decreases, and the specific surface area increases.

Due to the fact that most of the atoms are located on the surface of the particles, and the chemical properties are very active, it is easy to produce chemical reactions which can not occur in the macroscopic state.

In optical properties, the reflection coefficient decreases with the decrease of particle size. The smaller the particle size, the deeper the color, that is, the stronger the optical absorption ability of the nanoparticles, showing a strong absorption spectrum of broadband, until the black.

2.2 quantum confinement effect

Quantum dots are made up of a small number of atoms. Due to the limitation of the size, the motion of the electrons in the interior of the quantum dots is limited and can not move freely. It is this effect that leads to the appearance of a quantum like discontinuity of the electron energy level, so that quantum dots are also called "artificial atoms". The "artificial atom" is no longer the band spectrum of the ordinary crystal when it is excited, but has a very narrow linear spectrum like an atom.

2.3 quantum size effect

The biggest characteristic of quantum dots is that the energy gap increases with the increase of grain size. The larger the grain size is, the smaller the energy gap is. In other words, the smaller the quantum dots, the shorter the wavelength of light (blue), the greater the quantum dots, the longer the wavelength of light (red shift). According to the size effect of quantum dots, we can use the method to change the size of the crystal to change the luminescence spectrum, and no longer need to change the chemical composition of quantum dots (see Figure 2).

Luminescence of 2.4 quantum dots LED

Quantum dots are the basic materials of QLED luminescence. The realization of QLED luminescence mainly has two forms: one is used as the light conversion layer in GaN based LED, the effective absorption of blue emission wavelength in the visible range can be adjusted accurately; two is the use of the electroluminescent form, the coating on the thin film electrode between the light (see Figure 3).

3 historical review: from quantum dots to QLED

The last century at the beginning of 80s, the Baer Luis Bruce Laboratory (Louis Brus), and the former Soviet Union yof Institute Alexander Evros (Alexander Efros) and Dr. Victor Klimov (Victor I. Klimov), many researchers found that the fluorescence of different diameter of CDs particles will produce different colors under conditions of passion. It is found that the correlation between the size and color of quantum dots