Light and electric field induced unusual large-scale charge separation in hybrid semiconductor objects

Abstract

Separation of electric charges is the most crucial phenomenon in natural photosynthesis, and is also extremely important for many artificial energy conversion systems based on semiconductors. The usual roadblock in this context is the fast recombination of electrons and holes. Here we demonstrate that the synergy of light and electric fields allows separating very efficiently electric charges over an unusually large distance in TiO₂. The generated internal electric field can also be used to shuttle electrons simultaneously to the two opposite sides of a hybrid TiO₂–polyaniline object. This counterintuitive behavior is based on the combination of the principles of bipolar electrochemistry and semi-conductor physics.