TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The carbon nanotubes functionalized with a semiconducting polymer are dispersed (randomly dispersed) within the electrically insulating matrix, or randomly dispersed within a region or sublayer of the electrically insulating matrix, or within the whole of the electrically insulating matrix. The electrically insulating matrix comprises an electrically insulating organic material, or a dielectric inorganic material, preferably an electrically insulating organic polymer. The carbon nanotubes are coated at least in part with the semiconducting polymer, or wrapped in the semiconducting polymer. The semiconducting polymer is a conjugated polymer or a hole-transporting polymer. The carbon nanotubes are single-walled (preferred) or multi-walled carbon nanotubes. The carbon nanotubes are semiconducting carbon nanotubes, metallic carbon nanotubes, or a mixture of semiconducting carbon nanotubes and metallic carbon nanotubes. The component for transporting charge is a hole-transporting component or a charge-transporting layer. The charge-transporting layer comprises a first sub-layer in contact with a second sub-layer, where both the first sub-layer and the second sub-layer comprise the electrically insulating matrix, and the carbon nanotubes functionalized with a semiconducting polymer and disposed in the electrically insulating matrix, where the concentration of the carbon nanotubes functionalized with a semiconducting polymer is greater in the first sub-layer than in the second sub-layer. The charge-transporting layer is a p-type layer. The photovoltaic device comprises a photoactive region disposed between a first electrode and a second electrode, where the photoactive region comprises the charge-transporting layer. The photoactive region further comprises a photoactive material. The photoactive material is in contact with the charge-transporting layer. The photoactive material comprises a photoactive semiconductor or a photosensitising dye. The photoactive material comprises a photoactive semiconductor comprising a perovskite (preferred), gallium arsenide, lead selenide, lead sulfide, indium arsenide, indium phosphide, copper indium selenide, copper zinc tin sulfide, copper zinc tin selenide, copper zinc tin selenide sulfide, copper indium gallium selenide, copper indium gallium diselenide, and copper indium gallium diselenide sulfide. The perovskite has a band gap of less than or equal to 3 electronvolt (eV), preferably less than or equal to 2 eV. The photoactive material comprises an organometal halide perovskite of formula ((A1)(B1)(X1)3) (I) or a mixed-halide perovskite of formula ((A2)(B2)(X2)3) (II)A1 = at least one organic cation;B1 = at least one metal cation comprising Sn2+, Pb2+, Cu2+, Ge2+, Ni2+ (all preferred), Ca2+, Sr2+, Cd2+, Mn2+, Fe2+, Co2+, Pd2+, Yb2+ or Eu2+;X1 = at least one halide anion;A2 = at least one organic cation of formula (R1R2R3R4N)+ and (R5R6N=CH-NR7R8)+;R1-R8 = 1-20C alkyl or aryl (both optionally substituted);B2 = at least one divalent metal cation, preferably Sn2+, Pb2+, Cu2+, Ge2+, Ni2+; andX2 = at least two different halide anions.The photoactive material is in contact with the first sub-layer of the charge-transporting layer. The photoactive region comprises: the charge-transporting layer; the photoactive material; and a mesoporous scaffold layer, comprising a mesoporous dielectric scaffold material or a mesoporous charge-transporting scaffold material, where the photoactive material is disposed between the charge-transporting layer and the mesoporous scaffold layer. The photoactive material is disposed in pores of the mesoporous scaffold layer. The charge transporting layer is a hole-transporting layer, and the mesoporous scaffold layer comprises a mesoporous dielectric scaffold material or a mesoporous n-type scaffold material. The photoactive region further comprises a compact layer of a semiconductor, disposed between the mesoporous scaffold layer and one of the electrodes. The compact layer is a compact layer of an n-type semiconductor. The mesoporous dielectric scaffold material is an oxide of aluminum, germanium, zirconium, silicon, yttrium or ytterbium, or alumina silicate. The mesoporous n-type scaffold material is: a mesoporous oxide of titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, cadmium, or a mesoporous oxide of a mixture of at least two of the metals; a mesoporous sulfide of cadmium, tin, copper, zinc or a mesoporous sulfide of a mixture of at least two of the metals; a mesoporous selenide of cadmium, zinc, indium, gallium or a mesoporous selenide of a mixture of at least two of the metals; or a mesoporous telluride of cadmium, zinc, cadmium or tin, or a mesoporous telluride of a mixture of at least two of the metals. The n-type semiconductor of the compact layer, when present, is: an oxide of titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, cadmium, zirconium or an oxide of a mixture of at least two of the metals; a sulfide of cadmium, tin, copper, zinc or a sulfide of a mixture of at least two of the metals; a selenide of cadmium, zinc, indium, gallium or a selenide of a mixture of at least two of the metals; or a telluride of cadmium, zinc, cadmium or tin, or a telluride of a mixture of at least two of the metals. The mesoporous scaffold layer comprises mesoporous alumina. The compact layer is a compact layer of titanium dioxide. The photoactive region comprises: an n-type region comprising at least one layer of an n-type material; a p-type region comprising at least one layer of a p-type material; and a layer of the photoactive material disposed between the n-type region and the p-type region, where the charge-transporting layer is a layer of a p-type material in the p-type region or a layer of an n-type material in the n-type region. The charge-transporting layer is a layer of a p-type material in the p-type region. The n-type region comprises at least one layer of an n-type material comprising a metal oxide, a metal sulfide, a metal selenide, a metal telluride, a perovskite, amorphous silicon, an n-type group-IV semiconductor, an n-type group III-V semiconductor, an n-type group II-VI semiconductor, an n-type group I-VII semiconductor, an n-type group IV-VI semiconductor, an n-type group V-VI semiconductor, and an n-type group II-V semiconductor, any of which may be doped or undoped. The layer of the photoactive material forms a planar heterojunction with the n-type region or the p-type region, where the layer of the photoactive material forms a first planar heterojunction with the n-type region and a second planar heterojunction with the p-type region. The substrate comprises a photoactive material and the surface of the substrate on which the carbon nanotubes functionalized with a semiconducting polymer are disposed is a surface of the photoactive material. The substrate further comprises: a mesoporous scaffold layer, where the photoactive material is disposed on the mesoporous scaffold layer, which mesoporous scaffold layer comprises a mesoporous dielectric scaffold material or a mesoporous charge-transporting scaffold material; a compact layer of a semiconductor, where the mesoporous scaffold layer is disposed on the compact layer; an n-type region comprising at least one layer of an n-type material, or a p-type region comprising at least one layer of a p-type material, where the photoactive material is disposed on the n-type region or the p-type region, optionally the photoactive material forms a planar heterojunction with the n-type region or the p-type region on which it is disposed; and an electrode material. The electrode material comprises a transparent conducting oxide, optionally where the transparent conducting oxide is one of Indium tin oxide, fluorine doped tin oxide and aluminum doped zinc oxide. Preferred Process: The process comprises: (a1) disposing the carbon nanotubes functionalized with a semiconducting polymer on the surface of the substrate; and the step (b) as above per se. The step of (a1) comprises: (a11) disposing a composition comprising a solvent and the carbon nanotubes functionalized with a semiconducting polymer on the surface of the substrate; and (a12) removing the solvent. The step (a11) comprises disposing the composition on the surface of the substrate by spin-coating, slot-die-coating or spray coating. The process further comprises: producing the carbon nanotubes functionalized with a semiconducting polymer; and disposing a counter electrode material on the component for transporting charge, where the counter electrode material comprises a metal. The step of producing the carbon nanotubes functionalized with a semiconducting polymer comprises: (a1a) preparing a composition comprising carbon nanotubes, a solvent and, dissolved in the solvent, the semiconducting polymer; (a1b) agitating the composition, optionally by sonicating the composition; (a1c) separating solid material from the composition, which solid material comprises non-functionalized carbon nanotubes and carbonaceous particles, and recovering the supernatant; (a1d) treating the supernatant to induce aggregation of carbon nanotubes functionalized with the semiconducting polymer, optionally by heating the supernatant and/or by adding a further solvent to the supernatant; (a1e) recovering the aggregated carbon nanotubes functionalized with the semiconducting polymer; (a1f) washing the carbon nanotubes functionalized with the semiconducting polymer with a solvent, to remove any free semiconducting polymer; (a1g) recovering the carbon nanotubes functionalized with the semiconducting polymer; and (a1h) optionally repeating (a1f) and (a1g). The step (b) comprises either: (b1) disposing onto the carbon nanotubes functionalized with a semiconducting polymer a composition comprising a solvent and the electrically insulating matrix, and (b2) removing the solvent; or disposing the electrically insulating matrix onto the carbon nanotubes to form a first sub-layer, which first sub-layer comprises the electrically insulating matrix and, disposed in the electrically insulating matrix at a first concentration, the carbon nanotubes functionalized with a semiconducting polymer, and continuing to dispose the electrically insulating matrix to form a second sub layer on the first sub-layer, where the second sub-layer comprises the electrically insulating matrix and, disposed in the electrically insulating matrix at a second concentration, the carbon nanotubes functionalized with a semiconducting polymer, where the second concentration is less than the first concentration. The electrically insulating matrix comprises an electrically insulating organic polymer and the step (b) comprises: (b11a) disposing onto the carbon nanotubes functionalized with a semiconducting polymer a composition comprising a solvent and the electrically insulating organic polymer, and (b12a) removing the solvent; or (b11b) disposing onto the carbon nanotubes functionalized with a semiconducting polymer a composition comprising at least one monomer suitable for producing an electrically insulating organic polymer, and (b12b) polymerizing the monomers, thus producing the electrically insulating organic polymer; or (b11c) disposing onto the carbon nanotubes functionalized with a semiconducting polymer a composition comprising an uncured precursor to an electrically insulating organic polymer, and (b12c) curing the composition, thus producing the electrically insulating organic polymer. The steps (b11a)-(b11c) comprise disposing the composition onto the carbon nanotubes functionalized with a semiconducting polymer by spin-coating, slot-die-coating or spray coating.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The electrically insulating organic polymer comprises a poly(acrylate), a poly(methacrylate), a polyvinyl alcohol, a polystyrene, a polybutyrate, a polyimide or a polycarbonate, preferably poly(methyl methacrylate). The semiconducting polymer comprises: a polythiophene, such as poly(3-hexylthiophene), poly(3-octylthiophene) or poly(3-dodecylthiophene); a polyfluorene, such as poly(9,9-dioctofluorene), poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) or poly(indenofluorene); or a poly(phenylene vinylene).