The energy level alignments of nucleosides fabricated between conventional Al and indium tin oxide (ITO) electrodes by means of a vacuum electrospray deposition technique were investigated using in situ ultraviolet and X-ray photoelectron spectroscopy measurements. The electronic structures of four nucleosides - deoxyguanosine, deoxyadenosine, deoxycytidine, and deoxythymidine - were determined, and their interactions with Al and ITO were analyzed. When in contact with ITO, each nucleoside showed an interface dipole that reduced the work function. On the other hand, when Al was deposited on the nucleoside layers, strong chemical interactions were observed due to electron transfer from Al to the nucleosides. Compared to their nucleobase counterparts, nucleosides commonly had lower ionization energies (IEs) and electron affinities (EAs). The origin of this difference in electronic structure was analyzed with density functional theory calculations. The sugar moieties in the nucleosides were found to induce electron-donating effects on the base moiety and led to reductions in IE and EA.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (Grant Nos. NRF-2015R1C1A1A01055026 and 2012M3A7B4049801) and by Samsung Display Company.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films