Electric-Field-Assisted Charge Generation and Separation Process in Transition Metal Oxide-Based Interconnectors for Tandem Organic Light-Emitting Diodes

The charge generation and separation process in transition metal oxide (TMO)‐based interconnectors for tandem organic light‐emitting diodes (OLEDs) is explored using data on electrical and spectral emission properties, interface energetics, and capacitance characteristics. The TMO‐based interconnector is composed of MoO3 and cesium azide (CsN3)‐doped 4,7‐diphenyl‐1,10‐phenanthroline (BPhen) layers, where CsN3 is employed to replace the reactive metals as an n‐dopant due to its air stability and low deposition temperature. Experimental evidences identify that spontaneous electron transfer occurs in a vacuum‐deposited MoO3 layer from various defect states to the conduction band via thermal diffusion. The external electric‐field induces the charge separation through tunneling of generated electrons and holes from MoO3 into the neighboring CsN3‐doped BPhen and hole‐transporting layers, respectively. Moreover, the impacts of constituent materials on the functional effectiveness of TMO‐based interconnectors and their influences on carrier recombination processes for light emission have also been addressed. The impacts of constituent materials on the functional effectiveness of transition metal oxide‐based interconnectors in tandem organic light‐emitting diodes are addressed. Spontaneous electron transfer occurs in a vacuum‐deposited MoO3 layer from various defect states to the conduction band via thermal diffusion. The external electric field induces charge separation through tunneling of generated electrons and holes from MoO3 into the neighboring electron‐ and hole‐transporting layers.