Direct patterning of organic light-emitting devices by organic-vapor jet printing

We demonstrate small molecular weight, fluorescent organic light-emitting devices directly patterned by organic-vapor jet printing (OVJP). In OVJP, a hot inert carrier gas picks up a molecular organic vapor that expands when passed through a nozzle, resulting in physisorption of the molecules onto a cooled substrate. A (1cm)2 flat organic semiconductor thin film is achieved by sweeping the nozzle over the substrate to print closely spaced lines. Using an array of nozzles, multiple parallel stripes are simultaneously printed at a growth rate of 3.4Åcm2∕s. Organic heterostructure fluorescent-light-emitting devices consisting of a broad area hole transport layer, followed by a striped electron transport layer, both printed by OVJP, yield an external quantum efficiency of (0.84±0.03)%, which is comparable to that of similar devices deposited by vacuum thermal evaporation.