Kenichi Nakayama

Stacked Device of Polymer Light-Emitting Diode Driven by Metal-Base Organic Transistor

We fabricated a new light-emitting device that combined a polymer light-emitting diode (PLED) and a vertical-type metal-base organic transistor (MBOT) through a floating electrode. By employing a layered floating electrode of Mg:Ag/Au, the MBOT on the PLED was operated successfully and a current amplification factor of approximately 20 was observed. The PLED luminescence exceeding 100 cd/m2 can be modulated using the MBOT with a low base voltage (2.8 V) and VCC (8 V). The emission contrast (on/off ratio) was improved with insertion of an insulating layer under the base, and the cut-off frequency was estimated to be 8 kHz. This device is expected to be a promising driving system of organic light-emitting diode (OLED), realizing low voltage and high numerical aperture.

Electron Injection and Transport Properties of Phenazine Compounds with Fused Rings

Electron injection and the transport properties of three phenazine compounds, tetrabenzophenazine (TBP), dibenzodipyridophenazine (DBDPP), and tetrapyridophenazine (TPP), were investigated to determine the effect of nitrogen atoms in fused-ring molecules. These three compounds worked as electron transport materials, exhibiting high electron mobility – on the order of 10-3 cm2 V-1 s-1. Increasing the number of nitrogen atoms deepened the energy levels and lowered crystallinity in vacuum-deposited films. In particular, TPP containing six nitrogen atoms showed very efficient electron injection from an aluminum cathode.