TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The intermediate layer consists of an electrolyte and a charge transport electrically conductive material. The charge transport electrically conductive material is an ionic liquid or a porous or lamellar inorganic material. The intermediate layer consists of the redox couple I-/I3- dissolved in an organic solvent, or a redox couple I-/I3- dissolved in an ionic liquid, or a redox couple I-/I3- confined in an inorganic material, or a redox couple I-/I3- confined in an inorganic material modified with organic molecules.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Disclosed): Preparation of the dye (I) involves reacting aldehyde derivative of formula D'-G'-C(=O)-H and heterocyclic compound of formula (II) to give the compound (I) (R'1 is H). Preferred Compounds: The compound (I) is conjugated with an optically active nanoparticle (NP), preferably fluorescent.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The passive substrate is glass or polymeric material. The polymeric material is selected from polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polyimide, 3-acetylcellulose and polyethersulfone. Preferred Definitions:    D'=nanoparticle selected from quantum dots with a diameter of 1-10 nm, composite quantum dots with a diameter of 2-50 nm, porous fluorescent silica nanoparticles with a diameter of 5-200 nm, non-porous fluorescent silica nanoparticles with a diameter of 5-200 nm, fluorescent polymeric nanoparticles with a diameter of 5-200 nm, fluorescent lipid nanoparticles with a diameter of 10-400 nm.    SPECIFIC COMPOUNDS - 40 Compounds are specifically claimed as the compound (I), e.g. 2-((E)-2-(4-diphenylamino-phenyl)-vinyl)-3,3-dimethyl-3H-indole-5-carboxylic acid (I'); 2-((E)-2-(4-diphenylamino-phenyl)-vinyl)-benzothiazole-6-carboxylic acid; 2-((E)-2-(4-diphenylamino-phenyl)-vinyl)-benzooxazole-6-carboxylic acid; 2-((E)-2-(5-(4-diphenylamino-phenyl)-thiophen-2-yl)-vinyl)-3,3-dimethyl-3H-indole-5-carboxylic acid; and 2-((E)-2-(5'-(4-(bis-(9,9-dimethyl-9H-fluoren-2-yl)-amino)-phenyl)-(2,2')bithiophenyl-5-yl)-vinyl)-3,3-dimethyl-3H-indole-5-carboxylic acid.    EXAMPLE - Diphenylaminobenzaldehyde (3.3 mmol) was reacted with 2,3,3-trimethyl-3H- indolo-5-carboxylic acid (5 mmol) in a solution of sodium hydroxide (NaOH) in triethylamine for 12 hours at 80 degrees C. After work up, 2-((E)-2-(4-diphenylamino-phenyl)-vinyl)-3,3-dimethyl-3H-indole-5-carboxylic acid was obtained.