Vladimir Bulovic

Achieving full-color organic light-emitting devices for lightweight, flat-panel displays

We review recent results in the field of organic light-emitting devices (OLEDs), with particular attention to the application of organic light-emitting devices to ultra-lightweight, full color, flat-panel displays. We show that OLED brightness, efficiency, operating voltage, and lifetime is sufficient to compete with other flat-panel display technologies such as backlit liquid crystal displays. We describe a novel, tunable OLED consisting of vertically stacked, transparent light-emitting devices which can serve as a color-tunable element in high-resolution full-color display., In addition, the unique physical properties of organic thin films allow for flexible, conformable, or foldable displays which are unobtainable with conventional, inorganic semiconductor technologies.

A surface-emitting vacuum-deposited organic light emitting device

We demonstrate a vacuum-deposited organic light emitting device which emits from its top surface through a transparent indium-tin-oxide anode. This device employs a novel protective cap layer which prevents damage to the organic layers during sputter deposition of the anode, while also improving hole injection. Mechanisms of current transport and carrier injection from the contacts are investigated. This device configuration allows for integration of organic light emitting devices with n-channel field effect transistors used in display active matrix backplanes.

Unique optical properties of organic semiconductor lasers

We have studied the optical properties of two different organic semiconductor laser (OSL) structures: a waveguide edge-emitting OSL and an organic vertical-cavity surface-emitting laser (OVCSEL). The optically pumped edge-emitting OSL consists of a 3000 /spl Aring/ thick organic film vacuum-deposited onto a [100] InP substrate precoated with a 2-/spl mu/m thick layer of SiO/sub 2/. The organic films were grown in high vacuum by thermal coevaporation of tris(8-hydroxyquinoline) aluminum (Alq/sub 3/) and DCM molecules at mass ratios from 10:1 to 200:1. The organic film forms a slab optical waveguide with the SiO/sub 2/ cladding layer on one side and air on the other. The laser optical cavity is formed by the 7% reflective facets of the as-deposited organic film, which conforms to the cleaved parallel edges of the substrate. Unique optical and electronic properties of these OSLs such as thermal stability of emission wavelength, lasing threshold and output power, extremely narrow linewidth combined with a low material cost, and ease of integration of amorphous organic films with other optoelectronic devices make these lasers attractive for a number of applications, such as optical communication, optical sensing, and memory.