opto_wele_oc_r tr_lo_dnic

80

UNIVERSI T Y OF BRAUNSCHWEIG

⁹⁰ an important step toward

₇₀ creating a practical trans- ₆₀ parent display. The scientists ₅₀ fabricated an array of or-

^Uop OLED

U_g

TTFT

Transmissivity (%)

40 ganic light-emitting diodes 30 (OLEDs)—including their ²⁰ driving circuits—on a thin 10

₀ glass sheet, the whole being 200 300 400 500 600 700 800 greater than 70% transparent λ (nm) in the visible but able to emit green light from the pixels

The seal of the Technical University of Braunschweig is seen through a transparent OLED device contain- _{when energized (see figure).} ing 10 pixels, one of them electrically connected in the power-off state (left) and switched on (center). The _{The electroluminescent area}

OLED transmits throughout the visible spectrum (right).

consists of a bilayer of hole-

and capable of light emission on demand. temperature of the plastic. and electron-transport hosts of organic Transparent flexible plastics are one ap- Now, a group at the Technische Uni- compounds 4, 4´, 4´´-tris(N-carbazolyl)t proach; however, they are sensitive to any versität, Institut für Hochfrequenztech- riphenylamine and 1, 3,5-tris(phenyl-2- manufacturing processes that raise the nik (Braunschweig, Germany) has taken benzimidazolyl)benzene, doped with