Vacuum-deposited, nonpolymeric flexible organic light-emitting devices

We demonstrate mechanically flexible, organic light-emitting devices (OLED's) based on the nonpolymetric thin-film materials tris-(8-hydroxyquinoline) aluminum (Alq₃) and $N$, $N^{\prime }$-diphenyl-$N$, $N^{\prime }$-bis(3-methylphenyl)1-$1^{\prime }$biphenyl-4, $4^{\prime }$ diamine (TPD). The single heterostructure is vacuum deposited upon a transparent, lightweight, thin plastic substrate precoated with a transparent, conducting indium tin oxide thin film. The flexible OLED performance is comparable with that of conventional OLED's deposited upon glass substrates and does not deteriorate after repeated bending. The large-area ($\sim 1$-${\mathrm{cm}}^2$) devices can be bent without failure even after a permanent fold occurs if they are on the convex substrate surface or over a bend radius of $\sim 0.5 \mathrm{cm}$ if they are on the concave surface. Such devices are useful for ultralightweight, flexible, and comfortable full-color flat panel displays.