Single-layered light-emitting diodes possessing methoxy-modified pyrazoloquinoline dyes in poly-N-vinylcarbazole matrix

A principal opportunity to operate by current-voltage and electroluminescent-current dependences for the single-layered light-emitting diodes (LED) on the basis of the polyvinylcarbazole (PVK) polymers doped by methoxy-substituted pyrazoloquinoline (PQ) emitting dye chromphore is demonstrated. The principal light-emitting parameters in the architecture ITO/PQ: PVK/Ca (Al) were investigated. The maximally achieved quantum efficiency of the investigated LED was equal to about 0.87% and corresponded to the brightness about the 44 Cd/m2. The absence of blue shift for the electroluminescence (EL) compared to PL may indicate on an absence of near-the-surface exciton diffusion for the methoxy-PQ contrary to the phenyl-methyl-substituted PQ. The quantum chemical calculations have shown principal role of the dye chromophore state dipole moments in the observed carrier kinetics determining the EL.