Interfacial charge transfer and charge generation in organic electronic devices

We have recently proposed that improvement of device performance using a buffer layer of molybdenum trioxide (MoO₃) originates from interfacial charge generation at an interface of MoO₃ and an organic hole-transport layer [17]. However, there is no clear experimental evidence enough to support the charge generation in our recent report. In this study, from comparison of current density-voltage characteristics of organic hole-only devices and ultraviolet/visible/near-infrared absorption spectra of composite films, we can conclude that the interfacial charge generation surly occurs to realize space-charge-limited currents of a wide variety of organic hole-transport layers. Moreover, a drastic increase in current density of a bilayer device of n-type C60 and p-type N,N′-diphenyl-N,N′-bis(1- naphthyl)-1,1′-biphenyl-4,4′-diamine (α-NPD) by using a MoO₃ layer can provide the evidence of the charge generation.