DURABLE MOLECULAR ORGANIC ELECTROLUMINESCENT DEVICES AND THEIR FREQUENCY RESPONSES TO A NEW ACCURATE DRIVING METHOD

Citation
H. Fujii et al., DURABLE MOLECULAR ORGANIC ELECTROLUMINESCENT DEVICES AND THEIR FREQUENCY RESPONSES TO A NEW ACCURATE DRIVING METHOD, IEICE transactions on electronics, E81C(7), 1998, pp. 1034-1040
Citations number
15
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Engineering, Eletrical & Electronic
ISSN journal
0916-8524
Volume
E81C
Issue
7
Year of publication
1998
Pages
1034 - 1040
Database
ISI
SICI code
0916-8524(1998)E81C:7<1034:DMOEDA>2.0.ZU;2-V
Abstract
In order to improve the running durability of organic electroluminesce nt devices (OELDs), the doping sites of molecular OELDs were optimized , and the frequency responses of the optimized devices were examined f or Mg-In/bis (10-hydroxybenzo[h]quinolinato) beryllium (BeBq(2))/N, N' -diphenyl-N, N'-(3-methylphenyl)-1, 1'-biphenyl-4, 4'-diamine (TPD)/4, 4', 4 ''-tris (3-methylphenylphenylamino) triphenylamine (MTDATA)/ITO . The TPD hole transport layer was the optimum doping site for 5, 6, 1 1, 12-tetraphenylnaphthacene (rubrene) dopant, and a very high efficie ncy of 13 cd/A at 0.13 kcd/m(2) was obtained for yellow emission. Half -decay times under a constant direct current density of 1.0 mA/cm(2) f rom an initial luminance of 0.13 kcd/m(2) extended to longer than 26,0 00 hours. The luminance of the optimized device decreases lineally wit h respect to the logarithm of the frequency as the frequency increases in the range from 1 kHz to 0.3 MHz when a square wave with a duty rat io of 50% and a maximum voltage of 5.0 V is applied. A new driving met hod involving frequency modulation is proposed. This may offer accurat e control of pixel luminance, and enable simple driving circuits adapt ed to highly integrated digital LSI chips, or the concept of system on glass.