ZnS:TbF3,ErF3,HoF3ACTFEL的亮度与跃迁几率的关系

测量了低浓度下ZnS:TbF3,ErF3和ZnS:TbF3,HoF3交流电致发光薄膜(ACTFEL)中的Tb3+,Er3+,HO3+主要发射峰的相对积分强度,并与Tb3+,Er3+,Ho3+主要发射能级的辐射跃迁几率及高浓度时的发光特性进行了比较,发现稀土氟化物掺杂的ZnS薄膜电致发光(ACTFEL)的最大亮度,不完全取决于稀土离予本身的辐射跃迁几率,而主要取决于稀土离子主要发射能级激发态的运动。本文首次给出了Tb3+离子在ZnS中的强度参数Ω2=3.2×10-19cm2,Ω4=1.6×10-19cm2,Ω6=2.6×10-19cm2,并应用这组Ωλ参数估算了Tb3+离子的交叉弛豫(cross-relaxation)几率。

THE RELATIONSHIP BETWEEN ACEL BRIGHTNESS AND TRANSITION PROBABILITIES IN ZnS:TbF3,ErF3,HoF3 THIN FILMS

We have measured the integrated intensities of main emission lines for Tb3+, Er3+, Ho3+ ions in ZnS. TbF3, ErF3 and ZnS:TbF3, HoF3 ACEL thin films (TF) at low concentration, furthermore, compared them with their transition probabilities and their ACEL characteristics at high concentration.It is found that when the concentration is low(-10-4mol),the concentration quenching process could be neglected and transition probabilities of the main emission energy levels 5D4 2H11/2+4S3/2, 5S2(6F4)for Tb3+, Er3+, Ho3+ ions can be determined by decay time. The transition probabilities of 5D4-7F5, 2H11/2+4S3/2-4I15/2 and 5S2 (5F4)-5I8 are about 5300s-1, 13000s-1 and 7700s-1, respectively. In this case,the integrated intensities of main emission lines for Tb3+, Er3+ and Ho3+ in ZnS ACELTF are approximately proportional to the transition probabilities. But the maximum brightness of ACEL in ZnS:Tb3+, ZnS:Er3+ and ZnS:Ho3+ thin films is about 2300cd/m2, 1100cd/m2 and 500cd/m2 respectively. Therefore, the maximum brightness of ACEL in ZnS thin films doped with rare earth fluorides is not determined completely by the transition probability of rare earth ions themselves, but mainly depends on the concentration quenching process dominated by the cross-relaxation process of main emission energy level of rare earth ions.In the present paper, the intensity parameters for Tb3+ in ZnS thin film have been obtained for the first time. They are Ω2=3.2×10-19cm2, Ω4=1.6×1019cm2. Ω6=2.6×1019cm2. They have been used to estimate the cross-relaxation probability between Tb3+ ions. The calculated result is in agreement with the experimental observation.