Characterization of Photoinduced Electron Tunneling in Gold/SAM/Q-CdSe Systems by Time-Resolved Photoelectrochemistry

• Published in: The journal of physical chemistry. B Vol. 104; no. 31; pp. 7266 - 7272
• Main Authors: Bakkers, E. P. A. M, Roest, A. L, Marsman, A. W, Jenneskens, L. W, de Jong-van Steensel, L. I, Kelly, J. J, Vanmaekelbergh, D
• Format: Journal Article
• Language: English
• Published: American Chemical Society 10.08.2000
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp000286u

Colloidal CdSe quantum dots were chemisorbed on a gold electrode using a variety of self-assembled monolayers (SAMs) consisting of dithiols and rigid disulfides. After absorption of a photon with an energy larger than the band gap, a long-lived excited state is formed in the quantum dot; this state can decay by electron tunneling via the gold. The rate of photoinduced tunneling was measured directly by intensity-modulated photocurrent spectroscopy (IMPS), and its distance dependence was studied using rigid SAMs separating the Q-CdSe and Au. The tunneling rate was found to depend exponentially on the distance, with a decay length of 2 Å.