We have fabricated a metal/organic semiconductor Schottky photodiode based on Al/pentacene junction. Since the energy band gap of thin solid pentacene was determined to be 1.82 eV, as characterized by direct absorption spectroscopy, we measured spectral photoresponses on our Schottky photodiode in the monochromatic light illumination range of 325-650 nm applying a reverse bias of -2 V. The main features of photo-response spectra were found to shift from those of direct absorption spectra toward higher photon energies. It is because the direct absorption spectra mainly show exciton level peaks rather than the true highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps while the photo-response spectra clearly represents the true HOMO-LUMO gap. Our photo-response spectra reveal 1.97 eV as the HOMO-LUMO gap.
|Number of pages||4|
|Journal||Thin Solid Films|
|Publication status||Published - 2004 Mar 22|
|Event||Proceedings of Symposium D on Thin Film and Nano-Structured - Strasbourg, France|
Duration: 2003 Jun 10 → 2003 Jun 13
Bibliographical noteFunding Information:
The authors are very appreciative of the financial support from KISTEP (Program No. M1-0214-00-0228), and they also acknowledge the support from Brain Korea 21 program.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry