Preparation And Properties Optimized Of La₃Si₆N₁₁:Ce³⁺ Phosphor-in-glass Films For Laser Lighting And Display

Since the advent of light-emitting diodes（LEDs）in the 1990s,they have achieved success due to their high efficiency and energy saving advantages.However,the problem of"efficiency decline"always exists in blue LED chips,which makes LED chips not suitable for high-brightness,high-power solid-state lighting applications.Compared to blue LED chips,the efficiency of blue laser diodes（LDs）increases linearly as the current density increases,do not have the above problems.Therefore,laser lighting technology,which combines blue laser diode with fluorescent materials,has become an effective way to obtain high-brightness,high-power white light lighting and display.The key to the development of laser lighting technology lies in the development of fluorescent conversion materials with excellent performance,of which high thermal dissipation and high temperature stability are indispensable,only in this way can withstand the excitation of high-power lasers.Based on this approach,various high-strength phosphor ceramics,phosphor-in-glass（Pi G）films and luminescent single crystals have been extensively studied.Among them,Pi G films show a great prospect in laser lighting and display applications because of its excellent comprehensive properties.In view of the lighting and display requirements of high power,high brightness and high color rendering,this work studied the preparation process,luminescence performance and heat dissipation performance of La₃Si₆N₁₁:Ce³⁺Pi G films,and carried out a series of adjustment and optimization of its microstructure,and finally applied in devices.The specific research contents are as follows:1.At present,the most used preparation method of Pi G films is low temperature co-sintering.By mixing glass powder with phosphor powder and sintering it on sapphire substrate,the mixing ratio of glass powder and phosphor powder,film thickness and sintering temperature conditions become the key factors affecting the luminescence properties of Pi G film.In this paper,adjustable high-quality white light laser was achieved by controlling the ratio,film thickness and sintering temperature.By optimizing the preparation process,LSN:Ce³⁺Pi G film（Phosphor to glass ratio=1:1,thickness 50μm）was prepared at 800℃.Its comprehensive performance is excellent.It can withstand the power density of 13.37 W/mm² blue laser for a long time,and the luminous efficiency reaches 79.7lm/W at the peak,and the maximum luminous flux is 797lm.2.In the current research,the most used way to improve the light efficiency is to plating Blue-Pass（BP）film on sapphire substrate with high thermal conductivity.At present,this work is to explore whether the addition of BP film will affect the Pi G film itself and its luminescence properties.The thermal stability of BP film and the luminescence saturation threshold and the change of luminous flux before and after adding BP film.Firstly,the sapphire substrate（with BP film）was held at 600°C,700°C,800°C and 900°C for 10 minutes in air atmosphere.The results showed that the linear penetrating rate of sapphire with excellent heat resistance did not change with the increase of calcination temperature,but the BP film was calcined at high temperature.The transmittance curve is slightly offset to the long wave direction,and the transmittance decreases a small part in the blue band,but it is still higher than that of sapphire itself.In addition,with the blue laser excitation,coated BP film through the membrane samples due to the launch of the yellow light reflected backward,thus luminous flux and luminous efficiency increased nearly 1 times,while the light saturation threshold fell by less than 5%,the results can show that high temperature and the process of preparation of Pi G film won’t cause too much influence of the BP film,Due to the reflectance curve of blue light passing through the film,the luminescence performance of the sample of Pi G film is obviously improved,and the laser saturation threshold of the sample is not affected.3.For the application of high-power laser lighting,we further optimized the thermal dissipation performance of Pi G film.By adding the third phase Al₂O₃ into the Pi G glass,we developed the composite La₃Si₆N₁₁:Ce³⁺Pi G film.Due to the good thermal conductivity of Al₂O₃ and its refractive index matching with glass powder and sapphire substrate,the composite Pi G film shows excellent thermal dissipation and optical properties.Moreover,as the scattering center of Al₂O₃,the light conversion efficiency of the sample can also be improved.In this work,the effects of different proportions of Al₂O₃,phosphor and glass powder concentration on the luminescence and thermal dissipation properties of composite Pi G films are analyzed in detail.The peak temperature of the final sample（Glass to Al₂O₃（Gt A）=2:5,50μm）is 22%lower than that of the undoped sample.The sample produced a white laser with a luminous flux of 3120lm,1.5 times that of the undoped sample.The color rendering performance of the sample is 69.7,the color coordinates are（0.3245,0.3655）,and the color temperature is 6612 K.These results show that under the designed composite structure,the Pi G film shows excellent thermal dissipation and luminescence performance,and shows a good prospect in the field of high brightness and high-power laser lighting and display.