New structure of white LED backlight - — Quantum dots mixed leds

In recently, according to researchers at the university of Ghent in Belgium found a using a mixture of quantum dots LED, LED by the blue LED light source is mixed with non-contact fluorescence of membrane materials, the main fluorescent membrane is red with cadmium sulphide selenide cadmium ( CdSe／CdS） Quantum dot material and mixed with europium ( Eu） Green fluorescent materials. Because of the quantum dot structure on the conversion of light have good light conversion rate, light spectrum of regulatory, narrow spectral band. So the researchers say the hybrid structure in terms of cost and efficiency with good performance. Research methods, the researchers used the red selenide cadmium and the cadmium sulfide ( CdSe／CdS） Quantum dots materials and green SrGa2S4: Eu2 + ( STG） To make the fluorescent membrane material, and will these materials dissolved in methyl ethyl ketone ( Contains certain toluene) In the solution. At the same time, the mixture will be dripping ways ( drop-casting) Plating on the 18 mm in diameter of thin glass. For fluorescent membrane, the researchers designed a variety of different fluorescent membrane structure to evaluate the performance of the leds. Simple red green fluorescent membrane structure such as | RG |; Use two pieces of glass separate fluorescent membrane ( In the middle is filled with air) 。 Or structure, such as | R | | G | | G | | R |; Using similar to the structure of the second, but the middle is filled with ethylene glycol, this structure can alleviate the problem of the refractive index matching, structure such as | R | | G | or | G | | R |. Research content of hybrid fluorescent membrane structure as shown in figure 1 a, | RAGA | mixed structure of LED color temperature of 7082 k, and in the CIE ( X, Y) The coordinates of ( 345). , its internal quantum efficiency ( 以) 80% ( Separate | R | is 71%, | G | 93%) 。 At the same time, the researchers found that the hybrid structure of light intensity attenuation and separate material have different place. According to figure 1 d, STG material attenuation almost no change, but the attenuation of the luminous intensity of quantum dots in the whole process ensure the rise. This mainly comes from the direct excitation and STG blue light material indirect excitation. Figure 1 mix of white LED light emitting spectrum a | RA | | | GA structure of optical | RA b | | | | RA and GA | | | | structure of optical c GA GA | | RA | and | GA | | RA | structure of red and green fluorescence spectrum d membrane luminous intensity attenuation figure separate fluorescent membrane structure by comparing figure 1 b, 1 c, the researchers found that the structure of a separate there is a strong order relationship. When the quantum dot material near the light source side, ｜RA｜｜GA｜） , the luminous intensity of STG material will be strong. Likewise, if STG material on this side of the light source ( ｜GA｜｜RA｜） , the luminous intensity of quantum dot material will also be suppressed. This kind of phenomenon is mainly comes from the lambert beer's law ( 啤酒, 朗伯定律) , at the bottom of the light conversion materials under blue light irradiation after general meeting had the highest luminous intensity. Than the air filled with separate structure, ethylene glycol filling | RA | | | and | GA GA | | RA | structure has higher red light green light intensity of luminous intensity and lower, this is due to the better material of refractive index matching led to STG optical coupling rate of rise, more and more green to red. At the same time, the high refractive index matching conditions, the green light from any Angle to the quantum dot material, thereby improving the average path length of light in a quantum dot material. Conclusions, the researchers found that the fixed fluorescent membrane structure, hybrid LED luminous efficiency depends on the fluorescent layer in the middle of the material ( As previously mentioned ethylene glycol) 。 Among them, the heavy absorption and fluorescence quantum dot material for green powder crystal (for) the red light absorption inhibitory effect is the main factor. In three kinds of fluorescent membrane structure, economic benefit is the best structure of high refractive index matching separated structure. Internship editor: zhi-zhao Yang