Abstract
From the analysis of current density-luminance-voltage characteristics of the double layered device in ITO/N,N'-diphenyl-N-N'bis(3-methylphenyl)-1,1'biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline)aluminum($Alq_3$)/Al, we divided the conductive mechanism by four region according to applied voltage. We have obtained a coefficient of ${\beta}_{ST}$ in schottky region (I) is $4.14{\times}10^{-24}$ at the electric field of $3.2{\times}10^5$ V/cm, a slope in negative resistance region (II) appears negative properties decreasing the current density J for proportional in -1.58 square at a electric field of $7.3{\times}10^5$ V/cm. A coefficient of ${\beta}_{PF}$ in Poole-Frenkel region (III) is $8.28{\times}10^{-24}$ at the electric field of $8.4{\times}10^5$ V/cm, it was confirm어 that ${\beta}_{PF}$ is agrees with a value that relates with ${\beta}_{ST}$ such as ${\beta}_{PF}=2{\beta}_{ST}$ as the ${\beta}_{PF}$ and 2 ${\beta}_{ST}$ satisfied a theoretical prediction. And it was obtained a potential barrier of ${\Phi}_{FN}$ in Fower-Nordheim region(IV) is 0.3 eV at the electric field of $11.2{\times}10^5$ V/cm.
