Energy transfer process to the emission center for the electroluminescence of ZnS thin films and the pure blue-emitting devices

1. 为了明确ZnS薄膜电致发光器件发射中心的激发过程，制作了各种器件并测量了几种发射性能。得到了以下结果：(1)测量了掺杂Tb^<3+>离子或Mn^<2+>离子的ZnS薄膜在极短宽度交变脉冲电压下的瞬态特性。Tb^<3+>离子和Mn^<2+>离子的发射在施加的脉冲电压内饱和。在320nm ~ 700nm波长范围内观察到ZnS宿主的宽带发射，其寿命很短。观测到的Tb^<2+>离子和Mn^<2+>离子的发射叠加在宽带发射上，并延迟到ZnS宿主的宽带发射。(2)光致发光的瞬态行为表现出与电致发光相似的特征。(3) ZnS主体的350nm发光，Mn^<2+>和Tb^<3+>在电致发光中表现出相似的退火温度依赖性。(4)从紫外光辐照电致发光的实验结果中观察到了解发射中心激发过程的宝贵结果。(5)从这些结果可以看出，电致发光器件的发射中心受到来自主体的能量传递的激发。在此激发过程的基础上，制备了掺杂Tm^<3+>离子的致蓝电致发光器件，得到了以下结果：(1)作为发射中心，TmOF中心比TmF_x中心效率更高。(2)研究了几种基质作为掺杂tm离子EL器件的基质材料。这些发射中最主要的谱线随宿主材料的种类而变化。随着主体材料带隙能量的增加，谱线向较短波长区域移动。

1. In order to clear the excitation process of the emission center for ZnS thin film electroluminescent devices, various devices were fabricated and several emission properties were measured. The following results were obtained.(1) The transient characteristics in ZnS thin-films doped with Tb^<3+> ions or Mn^<2+> ions under an alternating pulse voltage with very short width were measured. The emission from the Tb^<3+> ions and Mn^<2+> ions saturated within the applied pulse voltage. Broad-band emission intrinsic to the ZnS host was observed in the wavelength region from 320nm to 700nm with very short lifetime. The observed emission from Tb^<2+> ions and Mn^<2+> ions are superimposed on the broad-band emission and delayed to the broad-band emission from the ZnS host.(2) The transient behavior of the photoluminescence show similar characteristics to that in electroluminescence.(3) The 350nm emission from the ZnS host, Mn^<2+> emission and Tb^<3+> emission show a similar tendency toward the dependence of annealing temperature in electroluminescence.(4) The precious results for understanding the excitation process of the emission center were observed from the experimental results of ultravioletmlight irradiation on electroluminescence.(5) From these results, it is concluded that the emission center of the electroluminescent devices are excited by the energy transfer from the hosts.2. Blue-emitting electroluminescent devices doped with Tm^<3+> ion were fabricated on the basis of the excitation process, and the following results were obtained.(1) As the emission center, TmOF center is more efficient than TmF_x center.(2) As the host materials for Tm-ion-doped EL devices, several hosts were investigated. The most dominant lines in these emission varied with the kind of host materials. The spectral line shifted to a shorter-wavelength region with increase of the band-gap energy of host materials.