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 Kα 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.
Bibliographical noteFunding Information:
This work was supported by the Brain Korea 21 (BK21) project of the Korea Research Foundation (KRF) and the Korea Science and Engineering Foundation (KOSEF) through the National Core Research Center for Nanomedical Technology. Additional support by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Research Chair program is gratefully acknowledged.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry