Electrochemical Study of Silicon/Boron Phosphide Heterojunction Photoelectrodes

摘要

Two types of heterojunctions may be successful in the conversion of solar energy.In the first type heterojunction electrodes, type A, the valence band of the n-type substrate lies close to the conduction band of the n-type window to make it possible for the photoholes to drift into the conduction band of the window without facing a potential barrier on their way. In the second type electrodes, type B, a p-type semiconductor is coated with an n-type wide band gap material of which the conduction band is of the same energy as that of the substrate. In B type heterojunctions the optically generated electrons drift into the conduction band of the window without loss of energy and subsequently reach the electrolyte. It is still a long way to go from the described principles of type A and B heterojunction photoelectrodes to practical and efficient liquid-junction devices for solar energy conversion. Much of the success of these types of solar cells will lie in the chemical stability of the window material and the electrolyte. Also losses due to recombination of electron-hole pairs at the heterojunction and the semiconductor/electrolyte interfaces may further reduce the applicability of these devices.