Research And Application Of Phosphor In Glass Film In Laser Lighting Field

Laser lighting has become the most valuable and potential new lighting mode in the21st century due to its advantages of small size,low energy consumption,high brightness and long lighting distance.At present,the fluorescent materials that can be used for laser lighting include single crystal,fluorescent ceramics,phosphor in glass（Pi G）and phosphor in glass film（Pi GF）.Among the first three,single crystal and fluorescent ceramics have high requirements on cost and process,which limits their commercial application.In addition,the thermal conductivity of Pi G cannot withstand high power laser irradiation,and its application in laser lighting is also limited.The Pi GF has the advantages of low cost,mass production and excellent heat dissipation performance,which perfectly solves the problems of the above three materials and becomes the most important material form in the field of laser lighting.At the same time,with the development of the times,the requirements for laser lighting materials are getting higher and higher.It not only requires high luminous efficiency and excellent thermal stability,but also has high color rendering in special lighting environments（such as indoor stages and art galleries）.Therefore,it is urgent to develop new Pi GFs that can meet the above requirements.Based on this,in this paper,Pi GF with good luminous efficiency and excellent thermal stability were designed and prepared by screen printing and solid phase sintering.The effects of sintering temperature,the ratio of glass powder to phosphor（Gt P）,and the thickness of the film on the luminescent properties of the fluorescent film were studied.The composite Pi GFs were designed and prepared according to the color rendering problem,and the following main results were obtained:（1）A series of Pi GFs were prepared by changing the sintering temperature and Gt P ratio,and the effects of these two preparation conditions on the luminescent properties of Pi GF were studied.The results showed that the transmittance of Pi GF increased with the increase of temperature,while the photoluminescence quantum yield（PLQY）showed the opposite rule.In addition,with the increase of phosphors,the transmittance gradually decreases,while PLQY gradually increases.Finally,considering the balance of transmittance and PLQY,the optimal sintering temperature is determined as 600℃,and the optimal Gt P ratio is 1:4,which will be used as the best preparation condition in subsequent experiments.In order to improve the color rendering index of Pi GF,cyan phosphor(BSON:Eu²⁺)was used to fill the“cyan cavity”for the first time,and（YAGG+BSON）/CASN composite Pi GF was developed,and studied the effect of different color fluorescent layers on the luminescent properties of composite Pi GF.Finally,it was found that when the film combination of the composite Pi GF was G2R2,a high color rendering cold white light with a luminous efficiency（LE）of 58.72lm/W,a color rendering index（CRI）of 95,and a correlated color temperature（CCT）of 5500K can be obtained under blue laser excitation,indicating the application potential of the composite Pi GF in high color rendering lighting.（2）By changing the number of layers of film,a series of Pi GFs with different thickness were prepared to further study the influence of film thickness on the luminescent properties of Pi GF.The results show that the thickness has a great influence on the transmittance of Pi GF,and the thicker the thickness,the lower the transmittance.At the same time,the increase of thickness will lead to the increase of PLQY and luminescence intensity.After considering the balance between transmittance,heat accumulation and luminous efficiency,the optimal film thickness is determined to be 3 layers,that is,about 70μm.In addition,in view of the low luminous efficiency of Pi GF,we also studied the effect of special optical film（Si O₂-Ti O₂）on the luminous flux and luminous efficiency of Pi GF.It is found that this special optical film can improve luminous flux and lumen efficiency by at least 55%.（3）In order to optimize the preparation method and improve the luminous efficiency,the combination of YAGG+BSON was replaced.Lu AG phosphor with higher luminous efficiency was mixed with CASN phosphor to prepare composite Pi GF.The effect of CASN content on the luminescence properties of composite Pi GF was studied.The results show that the composite Pi GF with 10%CASN content can obtain warm white light with LE of101.62 lm/W,CRI of 92 and CCT of 3522 K under the excitation of blue laser,and the indoor lighting effect is excellent,indicating the application potential of the composite Pi GF in indoor lighting.