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Stabilized Blue Emission from Organic Light-Emitting Diodes Using Poly(2,6-(4,4-bis(2-ethylhexyl)-4 H -cyclopenta[ d ef ]phenanthrene))

2005; American Chemical Society; Volume: 38; Issue: 15 Linguagem: Inglês

10.1021/ma050812l

1520-5835

Hongsuk Suh, Youngeup Jin, Sung Heum Park, Doohwan Kim, Jinwoo Kim, Changyoon Kim, Jin Young Kim, Kwanghee Lee,

Conducting polymers and applications

A new electroluminescence (EL) polymer utilizing a new backbone, poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta-[def]phenanthrene)) (PCPP), with stabilized blue emission is reported. PCPP was synthesized from 4H-cyclopenta[def]phenanthrene over five steps. The photoluminescence (PL) spectra of PCPP did not show any peak in the long wavelength region even after annealing for 18 h at 150 °C in air. The OLED with the configuration of ITO/PEDOT:PSS/PCPP/Al generates EL emission with a maximum peak at 400 nm, low turn-on voltage (6.0 V), and excellent CIE coordinates (x = 0.17, y = 0.12) for the blue color without any filtering. The maximum brightness of the OLEDs using PCPP was 1500 cd/m2 at 14 V. The maximum luminescence efficiency of the polymer LEDs with PCPP was 0.70 cd/A at 180 mA/cm2. In addition to this, PCPP displays stabilized blue EL emission without any low-energy emission band in the region of 500−600 nm even after annealing for 18 h at 150 °C or operation of the device for 40 min in air.