Solar energy converter

Claim 1

A liquid-junction photoelectrochemical semiconductor cell adapted for producing electricity, fuel, chemicals and/or chemical energy by use of light radiation comprising: (I) a first electrode comprising: a bulk or film electrode comprising a photoactive true solid/solid solution semiconductor material having a band gap of approximately 1.4 eV and which, in the case of a film electrode, is disposed on a supporting electrically conductive substrate; (II) a second electrode comprising: a semiconductive or conductive layer which is transparent to radiation of energy corresponding to the band gap of said first electrode (I), and which is disposed on a supporting conductive substrate, wherein said substrate also is transparent to radiation of energy corresponding to the band gap of component (I), further characterized in that said second electrode, if a semiconductor, is of opposite conductivity type in relation to said first electrode; (III) an electrolyte disposed between, and in intimate contact with, both components (I) and (II); (IV) a means for receiving the electrical energy produced; wherein component (I) is further characterized in that said semiconductor material thereof is a photoactive true solid/solid solution mixed metal oxide semiconductor material derived from precursor substances selected from the group consisting of elemental metals, non-oxide metal compounds, and mixtures thereof; said phhotoactive true solid/solid solution mixed metal oxide semiconductor material corresponding to the formula A r ya M y vm O z -2 ; where said formula represents the stoichiometry of the basic repeating unit lattice cell; where M is the combination of component (a) metal and component (b) metal; A when present is at least one different metal which does not substantially alter the optical absorption accruing from M in the above formula; O represents oxygen, said formula being further characterized in that r, y, z, va and vm are defined by the relationship va(r)+vm(y)=2z, wherein r equals a value of from 0 to 2, inclusive, y is from 1 to 2, inclusive, z is from 1 to 7, inclusive, va equals the positive valence of A, vm equals the positive mean valence of M, and the valence of oxygen is -2; and wherein all said metal components of said formula are selected from the group consisting of boron, aluminum, tin, lead, the transition metals of families 1b through 7b, inclusive, and 8 of the periodic table of elements, and the lanthanide series; wherein M in the above formula comprises: (a) 50 to 99.9 mole percent, based on the total metals mole fraction, of one or more component (a) metals; and (b) 0.1 to 50 mole percent, based on the total metals mole fraction, of one or more component (b) metals; with the proviso that said component (b) metals are different than said component (a) metals and with the further proviso that said component (a) metals, when in comparable oxide form, have a larger band gap that said component (b) metals, when said component (b) metals are in their comparable oxide form; wherein said photoactive true solid/solid solution mixed metal oxide material's optical absorption edge is thereby optimized to approximately 1.4 eV.