Study of Hole-Injection Assisted Layer in Double-Layer Organic Light-Emitting Diodes by Electric-Field-Induced Optical Second-Harmonic Generation Measurement

Autor:	Mitsumasa Iwamoto, Yoshiaki Oda, Dai Taguchi, Masahiro Fukuzawa, Atsuo Sadakata, Takaaki Manaka
Rok vydání:	2013
Předmět:	Materials science business.industry General Engineering Analytical chemistry General Physics and Astronomy Second-harmonic generation Electroluminescence Threshold voltage Indium tin oxide Pentacene chemistry.chemical_compound chemistry Electric field OLED Optoelectronics business Diode
Zdroj:	Japanese Journal of Applied Physics. 52:05DC03
ISSN:	1347-4065 0021-4922
DOI:	10.7567/jjap.52.05dc03
Popis:	By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we studied the physical reason for the decrease in the threshold voltage of indium tin oxide (ITO)/N,N ′-di-[(1-naphthyl)-N,N ′-diphenyl]-(1,1′-biphenyl)-4,4′-diamine (α-NPD)/tris(8-hydroxy-quinolinato)aluminum(III) (Alq3)/Al diodes with a pentacene layer sandwiched between ITO and α-NPD layers. The amount of charge accumulated at the α-NPD/Alq3 interface was the same as that at ITO/α-NPD/Alq3/Al diodes under an applied DC voltage corresponding to the threshold voltage, although the charge accumulation proceeded faster. Results showed that the pentacene layer assists hole injection and the succeeding hole accumulation at the α-NPD/Alq3 interface, followed by the electroluminescence (EL) emission. The decrease in threshold voltage by inserting a hole-injection assisted layer such as pentacene is one way of improving the EL device performance.
Databáze:	OpenAIRE
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