NOVELTY - A photoelectric system comprises a semiconductor and a phosphorescent compound with an emission spectrum comprising photons with energy levels equal to or greater than the activation energy of the semiconductor, where the phosphorescent compound is characterized by the emission spectrum being produced by excitation of the phosphorescent compound with lower energy photons and the separation distance between the semiconductor and the phosphorescent compound is less than the distance at or above which scattering losses predominate.    USE - The photoelectric system and methods are useful for remediating chemical waste; for cleaning and sterilizing surfaces; for generating ozone; for purifying air or water contaminated with microbes or undesirable organic compounds; for producing hydrogen or a hydrocarbon fuel; for treating cancer; for killing or slowing the growth of tumor cells, pathogenic viruses, bacteria, fungi, allergens, parasites or prions; for suppressing the proliferation of hyperactive immune system cells in patients; and for removing toxins or allergens responsible for inflammation, kidney disease or liver disease from a patient in need (all claimed).    ADVANTAGE - The photoelectric system and methods can be efficiently to purify air and water, remediate chemical wastes, generate electricity, treat cancer, produce hydrogen fuel from water, clean and sterilize objects and surfaces.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) a method for remediating chemical waste comprising contacting material containing organic species for remediation with the photoelectric system and irradiating the semiconductor system with photons of sufficient energy to excite the phosphorescent compound to emit photons of sufficient energy to activate the semiconductor to generate species that degrade or decompose the volatile organic species;    (2) a method for cleaning and sterilizing surfaces comprising irradiating a surface coated with or formed from the photoelectric system with photons of sufficient energy to excite the phosphorescent compound to emit photons of sufficient energy to activate the semi-conductor to generate species that kill microbes or degrade or decompose organic substances on the coated surface;    (3) a method for generating ozone comprising contacting the photoelectric system with an oxygen source and irradiating the photoelectric system with photons of sufficient energy to excite the phosphorescent compound to emit photons of sufficient energy to activate the semiconductor and generate species that produce ozone from oxygen;    (4) a method for purifying air or water contaminated with microbes or undesirable organic compounds or organic matter comprising contacting the photoelectric system with an air or water source contaminated with microbes or undesirable organic compounds or organic matter and irradiating the photoelectric system with photons of sufficient energy to excite the phosphorescent compound to emit photons of sufficient energy to activate the semiconductor and generate species that purify the air or water by killing the microbes or degrade or decompose the undesirable organic compounds or organic matter;    (5) a method for producing hydrogen or a hydrocarbon fuel comprising contacting the photoelectric system with a source of hydrogen or a source of hydrocarbon fuel and irradiating the system with photons of sufficient energy to excite the phosphorescent compound to emit photons of sufficient energy to activate the semiconductor and generate species that decompose the hydrogen source to produce hydrogen or the hydrocarbon fuel source to produce hydrocarbon fuel;    (6) a method of treating cancer comprising delivering to the site of a tumor in a patient the photoelectric system, where the phosphorescent compound is a rare earth doped upconverting phosphor that upon excitation with IR wavelength photons emits photons capable of activating the semiconductor, and irradiating the tumor with IR light, so that the upconverting phosphor emits photons of sufficient energy to activate the semiconductor to generate species that kill tumor cells;    (7) a method for killing or slowing the growth of tumor cells, hematological cell malignancies, and other undesirable cell growths, malignant or benign comprising contacting the cells with the photoelectric system, and irradiating the system with IR light, so that the phosphorescent compound emits photons of sufficient energy to activate the semiconductor to generate species that kill at least a portion of the cells;    (8) a method for killing or slowing the growth of pathogenic viruses, bacteria, fungi, allergens, parasites or prions comprising contacting the viruses, bacteria, fungi, allergens, parasites or prions with the photoelectric system, and irradiating the system with IR light, so that the phosphorescent compound emits photons of sufficient energy to activate the semiconductor to generate species that kill or inactivate at least a portion of the viruses, bacteria or prions;    (9) a method for suppressing the proliferation of hyperactive immune system cells in patients suffering from an autoimmune or inflammatory disease comprising contacting the cells with the photoelectric system, and irradiating the system with IR light, so that the phosphorescent compound emits photons of sufficient energy to activate the semiconductor to generate species that kill an amount of the cells effective to suppress the disease;    (10) a method for removing toxins or allergens responsible for inflammation, kidney disease or liver disease from a patient in need, comprising contacting the toxins or allergens with the photoelectric system, and irradiating the system with IR light, so that the phosphorescent compound emits photons of sufficient energy to activate the semi-conductor to generate species that break down the toxins;    (11) an architectural product, automotive product, article of furniture, computer hardware or display or appliance surface coated with the photoelectric system;    (12) a ship hull or other maritime surface coated with the photoelectric system;    (13) a building facade or roof coated with the photoelectric system, where the phosphorescent compound is a rare earth doped upconverting phosphor that upon excitation with IR wavelength photons emits photons of sufficient energy to activate the semi-conductor; and    (14) a dye-sensitized solar cell characterized by a titanium dioxide layer comprising the photoelectric system, where the semiconductor is titanium dioxide.