NOVELTY - Substituted benzodithiophene compounds (I) are new.    USE - (I) are useful in luminescent solar concentrator, which is useful in a solar device (all claimed) such as photovoltaic cells and photoeletrolytic cells.    ADVANTAGE - (I) have high luminescence quantum efficiency, high stokes shift values, high values of the highest energy band maximum in the emission spectrum, and high molar extinction coefficient values, hence it is capable of increasing the number of photons that can be effectively converted into radiations that can be used by a solar device.    DETAILED DESCRIPTION - Substituted benzodithiophene compounds of formula (I) or their mixtures are new.    X = heteroatom comprising O, S, Se or Te;    R1-R4 = T1 or benzodithiophene groups of formula (II) or (III);    T1 = aryl, heteroaryl, cycloalkyl, heterocyclic (all optionally substituted), trialkyl, triarylsilane, dialkyl or diaryl-amine, dialkyl or diaryl-phosphine, alkoxy or aryloxy, thioalkoxy or thioaryloxy, cyano, H, halo such as F, Cl, Br, linear or branched 1-20C-alkyl, optionally saturated, optionally containing heteroatoms;    Y1, Z, W1, P1, Q, T = S, provided that at least one of P1, Q or T and at least one of W1, Z or Y1 is S, where in (III), Q and Z do not contemporaneously represent S, the remaining Y1, Z, W1, P1, Q and T represent a group comprising -C-R9, -C-R10, -C-R11 or -C-R12, so that the sum of the double carbon-carbon (C=C) bonds present in the two thiophene rings and in the benzene ring is equal to 5;    R5-R12 = T1; and    R5R6, R1R2, R2R3, R3R4 = aryl, heteroaryl, cycloalkyl, heterocyclic (all optionally substituted), optionally bound to each other so as to form, together with the other atoms to which they are bound, a cycle containing from 3-12C-atoms, optionally saturated, aromatic, optionally substituted with linear or branched 1-20C-alkyl, optionally saturated or unsaturated, optionally containing heteroatoms, trialkyl- or triaryl-silane, dialkyl- or diaryl-amine, dialkyl- or diaryl-phosphine, alkoxy or aryloxy, thioalkoxy or thioaryloxy, cyano, where the cycle optionally contains heteroatoms such as O, S, N, Si, P or Se.    Provided that at least one of R1-R4 is (II) or (III).