Abstract

Surface mediated electron transfer is the most ubiquitous of all surface reaction types and forms the basis of electrochemistry and many imaging technologies (photography, xerography). This process also holds great promise as a simple system for efficient solar energy conversion. Providing interfacial charge transfer processes can be made to occur competitively with thermalization dynamics, it should be possible to store energy as chemical potential at hybrid semiconductor/molecular junctions and avoid heat losses in conventional solid state solar cells (and thereby double theoretical efficiency limits). This specific mechanism is referred to as the hot electron model for semiconductor photochemistry [1] (Fig.1) and requires that the electron transfer occur in the strong coupling or adiabatic regime. The degree of electronic coupling between a discrete molecular state adsorbed to the surface and the highly delocalized band states of the single crystal is the key fundamental issue. In addition, the dynamics of interfacial charge transfer have to be quantified relative to the electron thermalization dynamics of field accelerated electrons (≤ 1 eV above the CBM) which are the dominant source of photoinduced hot electrons at semiconductor liquid junctions.

© 1996 Optical Society of America