五基色LED照明光源技术进展
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摘要
现有的白光LED是通过蓝光LED激发黄色荧光粉获得的,虽然其光电转换效率已远超白炽灯和日光灯,但其显色指数、色温和光效之间难以协调发展。采用多色高效率LED(红、黄、绿、青、蓝光)可合成低色温、高显色指数、高光效、对人眼安全与舒适的全光谱无荧光粉白光光源,是下一代高品质光源。其难点在于获得高光效黄光LED。目前我们在黄光LED光效提升方面取得重大突破,获得了电光转换功率效率高达21.5%的硅衬底InGaN基黄光LED(565nm,20A/cm~2),对应130 lm/W,远好于文献报道和可查询到的最高水平。基于红、黄、绿、青、蓝五色LED芯片合成的白光灯珠,显色指数94.8,色温3 263K,光效100.5 lm/W,达到了实用化水平。无荧光粉五基色LED照明技术省去了稀土这一稀缺资源,具有现实价值和战略意义,同时在可见光通信、情景照明、智能照明方面有优势。
The current LED white lighting is based on phosphor conversion of blue LEDs,although the efficiency is much higher than that of incandescent and fluorescent lamps,the main weak point is the difficulty of attaining the balance among color rendering index(CRI),color temperature(Tc) and light efficiency,and too much blue light may easily cause visual fatigue.Mixing multi-colors(Red/yellow/green/cyan/blue) LEDs to form white light can provides us a healthy,comfortable and phosphor-free light source with low Tc,high CRI and high efficiency,which is a high quality light source for next generation.To realize it,the key point is to make yellow LEDs efficient.Recently,we make a significant breakthrough on improving the efficiency of the yellow LEDs,efficient In Ga N based yellow LEDs with 21.5% wall-plugefficiency(WPE) at 565 nm and 20 A/cm~2 are realized on silicon substrate,the luminous efficiency is 130 lm/W which is far better than the highest level of the public reporting.By mixing blue,cyan,green,yellow and red LEDs,white LEDs with CRI up to 94.8,Tcof 3 263 K and efficacy above 100.5 lm/W were obtained.The performance is comparable with those commercialized white LEDs.The phosphor free five primary colors LED lighting technology can save the rare earth materials.It has important practical value and strategic significance,and it will show its advantages in the fields of light communication,scene lighting and smart lighting.
The current LED white lighting is based on phosphor conversion of blue LEDs,although the efficiency is much higher than that of incandescent and fluorescent lamps,the main weak point is the difficulty of attaining the balance among color rendering index(CRI),color temperature(Tc) and light efficiency,and too much blue light may easily cause visual fatigue.Mixing multi-colors(Red/yellow/green/cyan/blue) LEDs to form white light can provides us a healthy,comfortable and phosphor-free light source with low Tc,high CRI and high efficiency,which is a high quality light source for next generation.To realize it,the key point is to make yellow LEDs efficient.Recently,we make a significant breakthrough on improving the efficiency of the yellow LEDs,efficient In Ga N based yellow LEDs with 21.5% wall-plugefficiency(WPE) at 565 nm and 20 A/cm~2 are realized on silicon substrate,the luminous efficiency is 130 lm/W which is far better than the highest level of the public reporting.By mixing blue,cyan,green,yellow and red LEDs,white LEDs with CRI up to 94.8,Tcof 3 263 K and efficacy above 100.5 lm/W were obtained.The performance is comparable with those commercialized white LEDs.The phosphor free five primary colors LED lighting technology can save the rare earth materials.It has important practical value and strategic significance,and it will show its advantages in the fields of light communication,scene lighting and smart lighting.
引文
[1]HOLONYAK N,BEVACQUA S F.Coherent(visible)light emission from Ga(As1-xPx)junction[J].Applied Physics Letters,1962,1(4):82-83.
[2]AMANO H,SAWAKI N,AKASAKI I,et al.Metalorganic vapor phase epitaxial growth of a high quality Ga N film using an Al N buffer layer[J].Applied Physics Letters,1986,48(5):353-355.
[3]AMANO H,KITO M,HIRAMATSU K,et al.P-type conduction in Mg-doped Ga N treated with low-energy electron beam irradiation(LEEBI)[J].Japanese Journal of Applied Physics,1989,28(12A):L2112.
[4]NAKAMURA S.Ga N growth using Ga N buffer layer[J].Japanese Journal of Applied Physics,1991,30(10A):L1705
[5]NAKAMURA S,IWASA N,SENOH M,et al.Hole compensation mechanism of p-type Ga N films[J].Japanese Journal of Applied Physics,1992,31(5R):1258.
[6]国家半导体照明工程研发及产业联盟产业研究院.2016年中国半导体照明产业发展白皮书.2016.
[7]THOMAS D G.Isoelectronic Traps Due to Nitrogen in Gallium Phosphide[J].Physical review,1966,150(2):680-689.
[8]GROVES W O,HERZOG A H,CRAFORD M G.Effect of nitrogen doping on Ga As1-xPxelectroluminescent diodes[J].Applied Physics Letters,1971,19(6):184-186.
[9]KUO C P,FLETCHER R M,OSENTOWSKI T D,et al.High performance Al Ga In P visible lightemitting diodes[J].Applied Physics Letters,1990,57(27):2937-2939.
[10]KISH F A,STERANKA F M,DEFEVERE D C,et al.Very high-efficiency semiconductor wafer-bonded transparent-substrate(AlxGa1-x)0.5In0.5P/Ga P lightemitting diodes[J].Applied Physics Letters,1994,64(21):2839-2841.
[11]SATO H,CHUNG R B,HIRASAWA H,et al.Optical properties of yellow light-emitting diodes grown on semipolar(112-2)bulk Ga N substrates[J].Applied Physics Letters,2008,92(22):221110.
[12]SAITO S,HASHIMOTO R,HWANG J,et al.In Ga N Light-Emitting Diodes on c-Face Sapphire Substrates in Green Gap Spectral Range[J].Applied Physics Express,2013,6(11):1004.
[13]ZHANG Jianli,XIONG Chuanbing,LIU Junlin,et al.High brightness In Ga N-based yellow light-emitting diodes with strain modulation layers grown on Si substrate[J].Appllied Physics A,2014,114:1049-1053.
[2]AMANO H,SAWAKI N,AKASAKI I,et al.Metalorganic vapor phase epitaxial growth of a high quality Ga N film using an Al N buffer layer[J].Applied Physics Letters,1986,48(5):353-355.
[3]AMANO H,KITO M,HIRAMATSU K,et al.P-type conduction in Mg-doped Ga N treated with low-energy electron beam irradiation(LEEBI)[J].Japanese Journal of Applied Physics,1989,28(12A):L2112.
[4]NAKAMURA S.Ga N growth using Ga N buffer layer[J].Japanese Journal of Applied Physics,1991,30(10A):L1705
[5]NAKAMURA S,IWASA N,SENOH M,et al.Hole compensation mechanism of p-type Ga N films[J].Japanese Journal of Applied Physics,1992,31(5R):1258.
[6]国家半导体照明工程研发及产业联盟产业研究院.2016年中国半导体照明产业发展白皮书.2016.
[7]THOMAS D G.Isoelectronic Traps Due to Nitrogen in Gallium Phosphide[J].Physical review,1966,150(2):680-689.
[8]GROVES W O,HERZOG A H,CRAFORD M G.Effect of nitrogen doping on Ga As1-xPxelectroluminescent diodes[J].Applied Physics Letters,1971,19(6):184-186.
[9]KUO C P,FLETCHER R M,OSENTOWSKI T D,et al.High performance Al Ga In P visible lightemitting diodes[J].Applied Physics Letters,1990,57(27):2937-2939.
[10]KISH F A,STERANKA F M,DEFEVERE D C,et al.Very high-efficiency semiconductor wafer-bonded transparent-substrate(AlxGa1-x)0.5In0.5P/Ga P lightemitting diodes[J].Applied Physics Letters,1994,64(21):2839-2841.
[11]SATO H,CHUNG R B,HIRASAWA H,et al.Optical properties of yellow light-emitting diodes grown on semipolar(112-2)bulk Ga N substrates[J].Applied Physics Letters,2008,92(22):221110.
[12]SAITO S,HASHIMOTO R,HWANG J,et al.In Ga N Light-Emitting Diodes on c-Face Sapphire Substrates in Green Gap Spectral Range[J].Applied Physics Express,2013,6(11):1004.
[13]ZHANG Jianli,XIONG Chuanbing,LIU Junlin,et al.High brightness In Ga N-based yellow light-emitting diodes with strain modulation layers grown on Si substrate[J].Appllied Physics A,2014,114:1049-1053.