TECHNOLOGY FOCUS - ELECTRONICS - Preferred Heterojunction: The heterojunction is sensitized by at least one sensitizing agent. The n-type material and the cathode are separated by a distance of no less than 1 nm at their closest point, by the barrier layer. The n-type material and the cathode are separated by a porous barrier layer of at least one insulating material, over substantially all of the overlapping area between the n-type material and the cathode. Solid-state p-n heterojunction further comprises a solid p-type material (hole transporter) in the form of an organic semiconductor, preferably a molecular, oligomeric or polymeric hole transporter. Insulating barrier layer comprises at least one insulating metal oxide. Insulating metal oxide is selected from aluminum oxide (A12O3), silicon dioxide (SiO2), zirconium oxide (ZrO), magnesium oxide (MgO), hafnium dioxide (HfO2), tantalum pentoxide (Ta2O5), niobium pentoxide (Nb2O5), neodymium oxide (Nd2O3), samarium oxide (Sm2O3), lanthanum oxide (La2O3), scandium oxide (Sc2O3), yttrium oxide (Y2O3), nickel oxide (NiO), molybdenum oxide (MoO3), manganese oxide (MnO), SiAlO3, Si2AlO5, SiTiO4, AlTiO5, and its mixtures. Insulating barrier layer comprises at least one insulating polymer and/or block copolymer. The insulating polymer is selected from polystyrene, acrelate, methacrylate, methylmethacrylate, ethelene oxide, ethelene glycol, cellulose, imide polymers and its mixtures. Insulating block copolymer is selected from polyisoprene-block-polystyrene, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), polystyrene-block-polylactide, polystyrene-block-poly(ethylene oxide) and its mixtures. Insulating barrier layer has a thickness of 1 to 1000 nm. Insulating barrier layer has a porosity of 10 to 90%. The insulating barrier layer is composed of material having a resistivity of greater than 109 ohm-cm. Sensitizing agent comprises at least one dye selected from a ruthenium complex dye, a metal-phalocianine complex dye, a metal-porphryin complex dye, a squarine dye, a thiophene based dye, a fluorine based dye, a polymer dye, and its mixtures. The p-type material is an organic hole-transporter, preferably a molecular organic hole transporter. The organic hole-transporter is at least one optionally oligomerized, polymerized and/or cross-linked compound comprising (Ra)x-A-(Rp)z (tI), and formulae (tII), (tIII), (tIV), and (tV); or the organic hole-transporter comprises formula tXVII.N=if present, is a nitrogen atom;n=if applicable, is in the range of 1-20;A=a mono-, or polycyclic system comprising at least one pair of a conjugated double bond (-C=C-C=C-), the cyclic system optionally comprising one or several heteroatoms, and optionally being substituted, where in a compound comprising several structures A, each A may be selected independently from another A present in the same structure (tI-tV);A1-A4=if present, is an A independently selected from the A;v=number of cyclic systems A linked by a single bond to the nitrogen atom and is 1, 2 or 3;(R)w=an optional residue selected from a hydrocarbon residue comprising from 1 to 30 carbon atoms, optionally substituted and optionally comprising 1 or several heteroatoms, with w being 0, 1 or 2 provided that v + w does not exceed 3, and, if w=2, the respective Rw1 or Rw2 being the same or different;Ra=represents a residue capable, optionally together with other Ra present on the same structure (tI-tV), of decreasing the melting point of an organic compound and is selected from a linear, branched or cyclic alkyl or a residue comprising one or several oxygen atoms, where the alkyl and/or the oxygen comprising residue is optionally halogenated;x=the number of independently selected residues Ra linked to an A and is selected from 0 to a maximum possible number of substituents of a respective A, independently from the number x of other residues Ra linked to another A optionally present; with the proviso that per structure (I-V) there is at least one Ra being an oxygen containing residue as defined above; and, if several Ra are present on the same structure (tI-tV), they are the same or different; and where two or more Ra may form an oxygen-containing ring;Rp=represents an optional residue enabling a polymerization reaction with compounds comprising structure (tI-tV) used as monomers, and/or a cross-linking between different compounds comprising structures (tI-tV); where Rp may be linked to an N-atom, to an A and/or to a substituent Rp of other structures according (tI-tV), resulting in repeated, cross-linked and/or polymerized moieties of (tI-tV);z=the number of residues Rp linked to an A and is 0, 1, and/or 2, independently from the number z of other residues Rp linked to another A optionally present;(Ra/p)x/z and (R1-4a/p)x/z=if present, represent independently selected residues Ra and Rp; andR=1-6C alkyl or 1-6C O-alkyl.The n-type semiconductor material comprises at least one single metal oxide, compound metal oxide, doped metal oxide, carbonate, sulfide, selenide, teluride, nitrides and/or multicompound semiconductor, most preferably TiO2, tin oxide (SnO2), or ZnO. The n-type material is porous, preferably having a surface area of 1-1000 m2/g and preferably in the form of an electrically continuous layer, most preferably of thickness 0.1 to 20 mu m. It is selected from oxides of titanium (Ti), zinc (Zn), tin (Sn), tungsten (W) and its mixtures, where the n-type material is optionally surface coated. The n-type semiconductor material is essentially pure material or is doped throughout with at least one dopant material of greater valency than the bulk material (n-type doping) and/or is doped with at least one dopant material of lower valency than the bulk (p-type doping), and where the n-type material is optionally surface coated. Preferred Device: The device is encapsulated so as to be substantially isolated from atmospheric oxygen. EXAMPLE - No suitable example given.