Novaled and Eastman Kodak presented results of their joint research efforts in the area of white PIN OLEDs for AMOLED display applications at the SID. Based on Novaleds p- and n-type doped transport layers and Eastman Kodaks fluorescent emitter systems, single unit and tandem white OLEDs for the potential use in RGBW OLED displays were presented. For both approaches high efficiencies at low voltages combined with a very good white emission and long lifetimes were achieved.
For the single unit devices, 15.8 cd/A with a lifetime of 30,000 hours and colour coordinates of x,y = 0.32/0.35 (all at 1,000 cd/m²) were reached. Display simulations based on the power life model of Eastman Kodak showed, that this formulation is very well suited for the use in RGBW displays, reaching low power consumptions and long lifetimes of 30,000 hours and 15,000 hours at white points D65 and 10,000 K, respectively.
In the tandem device approach a current efficiency of 33.2 cd/A at colour coordinates x,y = 0.28/0.31 was achieved (all at 1,000 cd/m²). The lifetime of the device was 77,000 h compared to 51,000 hours that were reached with devices based on conventional Li-doping for the connector unit. This improvement can be mainly attributed to the better stability of the molecular doping in such connector unit systems.
In a display simulation the tandem device compares favourable with a conventional tandem device based on Li-doped pn connectors; the lifetime on display level could be improved from 38,000 to 53,000 hours.
