Charge carriers bulk recombination instead of electroplex emission after their tunneling through hole-blocking layer in OLEDs
Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing, 100044, P.R. China
Corresponding author: a firstname.lastname@example.org
Revised: 25 November 2005
Published online: 1 August 2006
Charge carriers bulk recombination instead of forming electroplex after their tunneling through a hole-blocking layer, i.e. 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), in organic electroluminescence (EL) device ITO/poly-(N-vinyl-carbazole)(PVK)/BCP/tris(8-hydroxyquinoline) aluminum (Alq3)/Al is reported. By changing the thickness of BCP layer, one can find that high electric fields enhance the tunneling process of holes accumulated at the PVK/BCP interface into BCP layer instead of forming “electroplex emission” as reported earlier in literatures. Our experimental data show that charge carriers bulk recombination takes place in both PVK layer and BCP layer, and even in Alq3 layer when BCP layer is thin enough. Further, it is suggested that PVK is the origin of the emission shoulder at 595 nm in the EL spectra of trilayer device ITO/PVK/BCP/Alq3/Al.
PACS: 73.20.-r – Electron states at surfaces and interfaces / 73.40.-c – Electronic transport in interface structures / 74.78.Fk – Multilayers, superlattices, heterostructures / 77.84.Jd – Polymers; organic compounds
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2006