Flexible Transparent Organic Light Emitting Devices on Plastic Films with Alkali Metal Doping as Electron Injection Layer

Flexible transparent organic light emitting devices (FTOLEDs) with of both mechanical flexibility and transparency to visible light were fabricated. For the design of FTOLEDs, the electron and hole injection layers and carrier blocking layers have to be taken into consideration. By the insertion of BCP as a hole blocking layer, carriers and excitons were confined to increase recombination rate. Moreover, by alkali metal doping of 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), the electron injection of FTOLEDs was improved. The device showed 70% transparency at 520 nm, and the total external quantum efficiency from both surfaces of the device was 0.36%. The radius of curvature of FTOLED cells was approximately 2.5 cm.