NOVELTY - A nitrogen-containing polycyclic dye (I) and merocyanine dyes (II), (IV) and (V) are new.    USE - In a semiconductor electrode in a solar cell, and in photoelectric conversion materials and devices (claimed).    ADVANTAGE - The compounds have an excellent stability with the passage of time and an excellent photoelectric conversion property.    DETAILED DESCRIPTION - An organic dye of formula (I) and merocyanine dyes of formulae (II), (IV) and (V), are new.    R1,R5 and R24 = alkyl, aralkyl, alkenyl, aryl or heterocyclic (all optionally substituted); or    R1+benzene ring = a cyclic ring;    R2,R3,R15 and R16 = H, alkyl, alkoxy, alkylthio, aralkyl, alkenyl, aryl, heterocyclic or mono- or di-substituted amino; or    R2+R3 = a cyclic structure directly or through a binding group;    R4 = a substituent having an acidic group;    X = methylene, O, S or optionally substituted amino;    n,m and b = 0 or 1;    R6 and R25 = alkyl, alkoxy (both optionally substituted) or halo;    R7,R8,R26 and R27 = H, alkyl, alkoxy, alkylthio, aryl, aryloxy, arylthio or heterocyclic moiety (all optionally substituted);    R9 = a substituent having an acidic group (preferably a group of formula (i));    R10 = a divalent alkylene or arylene group    X2 = O or S;    X3 = O, S, or dicyanomethylene;    X1 = a binding group (preferably a group of formula (ii));    X4 = a divalent alkylene forming 5- - 7-membered ring;    X5 = a binding group;    X1+amino group, X5+amino group and X8+amino group = a cyclic structure;    R13 = optionally substituted arylene or heterocyclic;    R14 = H, alkyl, alkoxy or halo;    R17 = a substituent having an acidic group (preferably a group of formula (iii));    X6 = O or S;    X7 = O, S or dicyanomethylene;    R18, R19 = H, alkyl, aryl or heterocyclic (optionally substituted) or form a ring;    R20,R21 and R22 = H, alkyl, alkoxy, aryl or heterocyclic;    R23 = alkylene or arylene;    R28 = a quaternary ammonium or metal salt of an acidic group, an amido or a substituent having an ester group;    p, q = 0-2.    Carbon-carbon double bond may be E or Z form.    INDEPENDENT CLAIMS are included for the following:    (a) a semiconductor electrode formed of a substrate having an electrically conductive surface, a semiconductor layer coated on the electrically conductive surface and a dye adsorbed on the surface of the layer. The dye contains (I), (II), (IV) and (V); and    (b) a photoelectric conversion device having the semiconductor electrode.