TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Layer: The semiconductor layer contains titanium oxide or zinc oxide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No general preparation given. Preferred Definitions:    Z=coupling group of formula (a);    R3,R4=H, optionally substituted alkyl or alkoxy;    R3+R4=ring;    Y'=O, S or NRa;    Ra=H, or alkyl or aryl (both optionally substituted);    asterisk=bond;    X=group of formula: -CH=C(-CN)(-COOM);and    M=H or salt formation cation.    SPECIFIC COMPOUNDS - 12 Spiro-bifluorene-type compounds (I) are disclosed e.g. 2-cyano-3-(7-(7-(9,9'-spirobi(fluorene)-2-yl)-2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)-2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)prop-2-enoic acid of formula (Ia), 2-cyano-3-(3-hexyl-5-(3-hexyl-5-(9,9'-spirobi(fluorene)-2-yl)thiophen-2-yl)thiophen-2-yl)prop-2-enoic acid, 2-cyano-3-(3-hexyl-5-(4-hexyl-5-(7-(9,9'-spirobi(fluorene)-2-yl)-2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)thiophen-2-yl)thiophen-2-yl)prop-2-enoic acid, 2-cyano-3-(5-(7-(9,9'-spirobi(fluorene)-2-yl)-2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)thieno(3,2-b)thiophen-2-yl)prop-2-enoic acid and 2-cyano-3-(7,7-dihexyl-10-(7-(9,9'-spirobi(fluorene)-2-yl)-2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)-3,11-dithia-7-silatricyclo(6.3.0.02,6)undeca-1(8),2(6),9-trien-4-yl)prop-2-enoic acid.    EXAMPLE - 5-(9,9'-Spirobi(fluorene)-2-yl)-7-(2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)-2H,3H-thieno(3,4-b)(1,4)dioxine (in g) (1.7) was dissolved in dry tetrahydrofuran (40 ml). n-Butyl lithium hexane solution (1.6 mol/L) was dropped at -78 degrees C in argon atmosphere. The solution was heated and dissolved in N,N-dimethyl formamide (0.32). Dry tetrahydrofuran (2 ml) was dropped and stirred. Water was added to the reaction solution, organic layer was extracted with diethyl ether (100 ml), and dried with magnesium sulfate. Solvent was distilled off under reduced pressure, and residue was purified. 7-(7-(9,9'-Spirobi(fluorene)-2-yl)-2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)-2H,3H-thieno(3,4-b)(1,4)dioxine-5-carbaldehyde (1.05) was obtained. The obtained compound (0.3) was dissolved in chloroform (90 ml), heated and refluxed. Cyano acetic acid (0.061) and piperidine (0.102) were added. Solvent was distilled off under reduced pressure after cooling. Small amount of tetrahydrofuran was added to residue, and acidified with diluted hydrochloric acid. Precipitated crystal was filtered, separated, washed with water and dried. 2-cyano-3-(7-(7-(9,9'-spirobi(fluorene)-2-yl)-2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)-2H,3H-thieno(3,4-b)(1,4)dioxin-5-yl)prop-2-enoic acid (0.193) was obtained at yield of 58%.