Figure 2
From: Inverted Quantum Dot Light Emitting Diodes using Polyethylenimine ethoxylated modified ZnO
Electronic energy level.
(a) Secondary cutoff region and valence (or HOMO) region after background removal obtained via UPS spectra of ZnO NPs, PEIE and ZnO/PEIE films deposited on ITO glass substrate, respectively and (b) corresponding energy level diagrams. (c) Schematic illustration of energy band diagram of inverted QDLEDs consisting of ITO/ZnO NPs/PEIE/CdSe-ZnO QD/poly TPD:PVK/MoO3/Ag. The ZnO NPs/PEIE energy level was estimated from UPS and optical absorption measurement. Other energy level values are taken from literatures. The pathways of the holes and the electrons are indicated by the arrows.
