Stable and efficient electrophosphorescent organic light-emitting devices grown by organic vapor phase deposition

An electrophosphorescent organic light-emitting device (PHOLED™) employing fac-tris(2-phenylpyridine)iridium $\left[\mathrm{Ir}{\left(\mathrm{ppy}\right)}_3\right]$ as the green emitting phosphor has been fabricated using a pilot-production organic vapor phase deposition (OVPD™) system. Highly controlled mass transport of the organic vapor to the substrate results in deposition rates of over $10\mathrm{\AA }∕\mathrm{s}$ and spatial uniformity better than $\pm 2\%$ across a $150\mathrm{mm}\times 150\mathrm{mm}$ substrate with less than $\pm 2\%$ run-to-run variations. The device current–voltage, luminous efficiency, and operational lifetime performances are compared to those of a similar device grown by conventional vacuum thermal evaporation (VTE). The green OVPD-grown PHOLED exhibits a maximum external quantum efficiency of $(7.0\pm 0.1)\%$ at a luminance of $1000\mathrm{cd}∕{\mathrm{m}}^2$ , comparable to the VTE device performance. The operational lifetime of the OVPD-grown devices was found to be comparable to or even somewhat longer than the lifetime achieved by VTE. Furthermore, PHOLEDs with emissive layers deposited at 4.8 and $10.8\mathrm{\AA }∕\mathrm{s}$ are compared, and demonstrate equivalent performance.