High pressure photoelectric studies of semiconductor-electrolyte systems

Data are presented which show the behavior of the valence and conduction band-edge energies (Ev and Ec, respectively) as a function of pressure for the n-type semiconductor electrodes TiO2, CdS, and CdSe. For TiO2, the 3 meV/kbar increase in the band-gap energy (Eg) is due entirely to an increase in Ec. For CdS, the 5.1 meV/kbar increase in Eg is the difference between the 9.5–11.5 meV/kbar increase in Ec and the (calculated) 4.5–6.5 meV/kbar increase in Ev. In the case of CdSe, both Ec and Ev move to lower energies with increasing pressure. Their behavior is complex.