저분자 화합물을 이용한 유기 전계발광소자의 제작과 특성 연구

Preparation and Properties of Organic Electroluminescent Devices Using Low Molecule Compounds

본 연구에서는 ITO (indium tin oxide)/glass 투명기판 위에 다층구조의 OELD (organic electroluminescent devices) 소자를 진공 열증착법으로 제작하였다. 발광층 재료로서 Alq₃(tris-(8-hydroxyquinoline)aluminum)물질을 사용하였고, 정공수송층으로는 TPD (triphenyl-diamine) 및 α-NPD를 사용하였다. 정공주입층 재료로서 CuPc (Copper phthalocyanine)를 사용하였다. 또한 QD2(quinacridone2) 물질을 Alq₃ 발광층내에 약 10Å 두께로 증착하여 발광효율 향상을 시도하였다. 제작된 모든 소자의 발광개시전압은 약 7 V 이었으며, 정공수송층으로 TPD 물질대신에 열적안정성이 우수한 α-NPD를 사용한 경우 휘도값과 발광효율이 개선되었다. Alq₃ 발광층 사이에 QD2 물질을 적층한 소자에서 발광효율은 1.55 lm/W 값을 나타내어 Alq₃ 발광층만을 사용한 경우에 비해 약 8배 발광효율이 향상되었다.

The multi-layered OELDs(organic electroluminescent devices) were prepared on the patterened ITO (indium tin oxide)/glass substrates by the vacuum thermal evaporation method. The Alq₃ (tris-(8-hydroxyquinoline)aluminum) low molecule compound was used as the light emission layer. TPD(triphenyl-diamine) and α-NPD were used as the hole transport layer. CuPc (Copper phthalocyanine) was also used as the hole injection layers. In addition, QD2 (quinacridone2) organic material with 10Å thickness was deposited in the Alq₃ emission layer to improve the luminance efficiency. The threshold voltage was about 7V for all devices. The luminance and efficiency of devices was improved by substitution the α-NPD for TPD as the hole as the hole transport layer. The luminance efficiency of the OELD sample with QD2 thin film in the Alq₃ emission layer was found to be 1.55 lm/W, which is about 8 times larger value compared to the sample without QD2 thin layer.