Electronic structure of NPB and BCP molecules probed by x-ray emission spectroscopy

Abstract

Soft x-ray absorption and emission spectroscopies have been employed to investigate the electronic structure and chemical bonding of two prototypical molecules, N,N(')-bis-(1-naphthyl)-N,N(')-diphenyl-1,1(')-biphenyl-4,4(')-diamine (NPB) and bathocuproine (BCP), which are frequently chosen because of their hole-transporting and hole-blocking properties, respectively. The resulting resonant C Kalpha x-ray emission spectra of these materials reveal different spectral features depending on the resonant excitation energy. According to the N absorption and emission spectra, the contribution of N atoms to the highest occupied and lowest unoccupied molecular orbitals is different for in NPB and in BCP. Detailed knowledge of these materials will allow tailoring charge transport properties of organic devices in order to develop high performance organic light-emitting diodes and photovoltaic cells.

Probing Interfacial Characteristics of Rubrene/Pentacene and Pentacene/Rubrene Bilayers with Soft X-Ray Spectroscopy

“…The DFT calculations were carried out using the nonlocal hybrid Becke three-parameter Lee−Yang−Parr (B3LYP) function with the basis set of 6-31G after optimizing the geometries of rubrene and pentacene using the same method. More details can be found elsewhere 2 (a) C 1s XAS spectra of (i) rubrene/pentacene, (ii) rubrene reference, and (iii) calculated carbon partial density of states of rubrene using DFT.…”

Retracted: Emerging 2D MXene/Organic Heterostructures for Future Nanodevices

“…Table 4 summarizes the bandgaps of various organic materials. [86,[105][106][107][108][109][110][111][112][113][114][115][116][117]…”

Degradation of the N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine by photon irradiation

“…Moreover, the properties of hole transport are due to the nitrogen that has a pair of electrons weakly bound and consequently easily ejected because of its sp 3 hybridization (an important contribution in the charge transport). As reported by Zhang et al [6,9] the good hole transporting properties of NPB are due to its electron deficiency of the energetically excited N that can be stabilized by the delocalized π character of adjacent C atoms because the N atoms are located at the junctions of the conjugated C chains. Fig.…”

“…1 present stronger degradation during the first minutes with respect to the other peaks. Based on the Density Functional Theory (DFT) it is possible to assign the dominant contributions to the UPS spectra by the partial density of states (not presented here) [6,7]. Peak a contains contribution mainly of the Benzene and Biphenyl rings, whereas peak c presents mainly contribution from Naphthalene.…”