Energy resolved-electrochemical impedance spectroscopy investigation of the role of Al-doped ZnO nanoparticles in electronic structure modification of polymer nanocomposite LEDs

•The novel method (energy resolved-electrochemical impedance spectroscopy) for the characterization of the electronic structure of nanocomposite thin film, which serves as an active layer in prepared PLEDs, is used.•Two kinds of nanoparticle addition effects were investigated.•(A) Non-specific modification of the polymer chain packing ordering results into polymer electronic structure alteration.•(B) Specific roles connected with the electronic structure of the particles, their conductivity and doping contribution to the electronic structure of the emissive layer.