Photoinduced Interfacial Charging and “Explosion” of Monolayer Pentacene Islands

Chemistry Chemistry
Physics Physics
R&D R&D
Technology Technology
Alex K. Shalek Alex K. Shalek

Chen L. et al.▾ Chen L., Cherniavskaya, O., Shalek, A.K., and Brus, L.

Nano Lett , Volume 5

November, 2005

Abstract

Abstract

Electrostatic force microscopy shows that the electric field gradients above pentacene monolayer islands on 2-nm SiO2/Si substrates, in a dark, dry nitrogen environment, display a wide distribution of signs and magnitude that is dependent on sample history. Under 12 mW/cm2 green (532 nm) illumination, pentacene islands accumulate positive charge because of photoexcited electron transfer across the oxide to the Si substrate. At a strong illumination of 60 mW/cm2, pentacene islands reform into small spherical particles, apparently because the positive charge Coulomb repulsion energy becomes comparable to the cohesive energy of the pentacene monolayer.