TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: Compound (I) is preferably of formula (IV).A2=direct bond, -O-, -S-, -PR3-, -NR4-, or -C(-R5)2-, preferably direct bond;two of X1-X3=-CR6=, with the remainder being -S-, -O-, or -NR7-;two of X4-X6=-CR6=, with the remainder being -S-, -O-, or -NR7-;R6,R7=H or substituent;andR6 groups,R6+R7=bond.(i) When X1 or X2 is -CR6= or -NR7-, R6 or R7 may form bond grouping with E1; X4 or X5 is -CR6= or -NR7-; When c is 1-3, R6 or R7 may form bond grouping with L1; and When c is 1-3, E1+L1, and each combination of L1 may form bond. Preferred Properties: The thin film has a film thickness of 0.2 nm to 1 mm. The energy difference (S1-T1) of the minimum singlet excitation energy (S1) obtained by the computing science method and the minimum triplet excitation energy (T1) is below 1.5 (eV). Preferred Definitions:    A1=direct bond.    EXAMPLE - (In g) 4,4'-dibromo-2,2'-bis(trimethylsilyl)bithiophene (0.446) and ether (10 mL) were put in a flask and cooled to -80 degrees C. n-Butyllithium (125 mL) (1.59M hexane solution) was, returned to room temperature, and stirred for 1 hour. About 0.2 mL was sampled and generation of dilithio forming component was confirmed by gas chromatography after hydrolysis. Tetrahydrofuran (10 mL) and diiodophenyl bismuth (0.415) were taken in a flask, followed by addition of the dilithio forming component at room temperature. After heating the mixture to 50 degrees C and distilling ether off, the mixture was heated to 70 degrees C and refluxed overnight. About 0.2 mL was sampled, and after hydrolysis, the solvent was distilled off after confirming the disappearance of dilithio forming component, the residue was hydrolyzed and extracted with toluene. The solvent was distilled off after drying. The residue was purified using toluene to obtain a crude product. The crude product was recrystallized using ethanol, to obtain 7-phenyl-2,5-bis-trimethylsilanyl-7H-3,4-dithia-7-bisma-cyclopenta(a)pentalene (0.322) with a yield of 57%, as pale yellow needle crystal. The energy difference was 1.24 eV. The compound showed red light emission in solid powder state and solution state (solvent: chloroform or 2-methyl-tetrahydrofuran) by UV-ray excitation (365 nm). The excitation life time of red-light emission was 5.6 mu seconds.