电致发光屏界面的阻抗谱和分形研究

采用电学方法测量ZnS:Mn,Cu DCEL粉末屏的复阻抗谱,运用多节RC等效电路、逾渗理论和自仿射康托体分形模型,分析EL屏界面和发光区在形成或老化过程的变化,认为逾渗相变形成发光区,发光区导电相分布具有分形特征,发光区内铜离子进一步迁移导致老化,老化屏发光区分维值趋于2。

An Investigation of the Impedance Spectrum and Fractal of DCEL Powder Devices During Forming and Aging Processes

A system is set to measure the electrical impedance-freqency spectrum of DCEL ZnS:Mn,Cu-powder panels. It's suggested that the forming process is one of the percolation phase transitions. Adopting RC parallel equivalent circuit model, the variation charecteristics of the luminescent region (LR) and the non-LR during the aging progress are investigated. It's confirmed that during the aging progress the width of the LR almost keeps unchanged and the resistivity increases rapidly and causes the failure of the EL panel. The small increase of resistance of the non-LR has little effect on failure. According to the Cantor-block fractal RC network theory, the CPA behavior of the admittance spectra is analoged and the fractal dimensions of the LR under the different aging voltages are calculated. The fractal dimention of the LR approaches to 2 for the aging panels.