(a) Materials for interlayer and light emitting polymers, (b) structures used for preparation of fluorescent red, green, and blue LEP devices, (c) HOMO and LUMO position of interlayer and each LEP layer.
AFM image of (a) pristine BFEC, (b) annealed film at , (c) annealed and washed (with toluene) film. Annealing time was 30 min onto the hot plate within a nitrogen atmosphere.
(a) Current density-voltage characteristics (b) brightness-voltage characteristics of Lumation Green 1304 LEP devices with and without a BFEC interfacial layer.
Power efficiency vs brightness characteristics of (a) green (b) red, and (c) blue LEP devices with and without a BFEC interfacial layer.
Hole mobility as a function of the square of electric field strength. (pristine BFEC and annealed film at ). Lines are linear fits to get the Poole-Frenkel parameters.
The EL and PL emission spectra of the LEP devices and polymeric films. (a) EL spectra of green, red, and blue LEP devices with and without BFEC. (b) PL spectra of Green 1304 LEP (pristine, bi-layers on top of BFEC) and BFEC (pristine, annealed at , and annealed/washed with toluene).
The decay of brightness in (a) green and (b) red LEP devices. The reference device, without an interfacial layer, is represented for comparison. The initial brightness was for green devices and for red devices.
Measured thicknesses of BFEC, Green 1304 polymer LEP, and BFEC/LEP bilayers. The annealed and washed BFEC polymer forms a thin interfacial layer composed of an insoluble residue, which cannot be measured directly by a surface profiler (Tencor P-10). Assumed BFEC interfacial layer thickness from the bilayer is .
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