TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The optically inert atom or the molecule or any part of the optically inert molecule exhibits a spin-orbit coupling constant of greater than 1000 cm-1, preferably greater than 4000 cm-1. The optically inert atom or the molecule does not exhibit absorptions or emissions in the emission region and/or in the highest occupied molecular orbital- or lowest unoccupied molecular orbital region of the organic molecule. The optically inert atom or the molecule comprises krypton or xenon, bromine-containing compounds, iodine-containing compounds, metal atoms, metal nanoparticles, metal ions, gadolinium complexes and/or lead complexes.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The amount of the composition in the emitter layer is 0.5-100 wt.%, preferably 6-30 wt.%.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic molecule exhibits the energy difference between the lowest excited singlet state and the underlying triplet state of less than 1500 cm-1, preferably less than 1000 cm-1. The organic molecule comprises: at least one conjugated organic group, preferably aromatic, heteroaromatic or conjugated double bonds, at least one chemically bonded donor group with electron-donating effect, and/or at least one chemically bonded acceptor group with electron-withdrawing effect. The organic molecule does not contain metal atom or metal ion. The organic molecule is of formulae (I)-(III). The ratio between the organic molecules and the optically inert atoms or molecules, is 1:0.1-1:50. The organic molecule exhibits an emission decay time of less than 500 milliseconds, preferably less than 1 microsecond at a temperature of 300 K. The composition exhibits an emission quantum yield of at least 30%, preferably greater then 80%, measured at a temperature of 300 K. The organic molecule comprises at least one deuterium atom. The organic molecule is embedded in a matrix or crosslinked with the matrix, where the matrix optionally exhibits at least one deuterium atom. The organic molecule comprises substituted acridine compounds of formula (IV).D1 = chemical group or substituent with electron-donating property, where (I)-(III) contains 1, 2 or several D1;A = chemical group or substituent with electron-withdrawing property, where (I)-(III) contains 1, 2 or several A;B1 = backbone, which is composed of conjugated organic groups comprising aromatic, heteroaromatic and/or conjugated double bonds; eitherR1-R9 = H, Br, I or groups, which form a donor D1 and/or an acceptor A; oradjacent groups of R1-R9 = (hetero)aromatic ring (optionally conjugated and optionally substituted by donor and/or acceptor groups), where Br and/or I are optionally bonded to the aromatic backbone through 1-2C alkyl; andR11 = H, alkyl, O or S, where R11 is optionally present.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The matrix is a polymer matrix or a polymer crosslinked matrix, where the matrix is covalently bonded with the organic molecule. The matrix exhibits at least one additive, preferably a bromine or iodine atom. EXAMPLE - No suitable example given.