Carrier behavior in special multilayer device composed of different transition metal oxide-based intermediate connectors

The impact of illumination on the connection part of the tandem organic light-emitting diodes was studied by using a special organic multilayer sample consisted of two organic active layers coupled with different transition metal oxide (TMO)-based intermediate connectors (ICs). Through measuring the current density-voltage characteristic, interfacial electronic structures, and capacitance-voltage characteristic, we observe an unsymmetrical phenomenon in current density-voltage and capacitance-voltage curves of Mg:Alq ₃/MoO₃ and MoO₃ composed devices, which was induced by the charge spouting zone near the ICs region and the recombination state in the MoO₃ layer. Moreover, Mg:Alq₃/MoO₃ composed device displays a photovoltaic effect and the V_oc shifts to forward bias under illumination. Our results demonstrate that the TMO-based IC structure coupled with photovoltaic effect can be a good approach for the study of photodetector, light sensor, and so on.