NOVELTY - A naphthalene derivative (I-1) or (I-2) is new.    USE - New naphthalene derivative is used as organic thin-film transistor material, organic-semiconductor material and coating solution for organic-semiconductor thin film for organic thin-film transistor (all claimed). Uses include but are not limited to solid-state image sensor of optical sensor, solar cell for energy conversion, gas sensor, organic rectifier, organic inverter, and information recording element.    ADVANTAGE - The organic thin-film transistor containing the naphthalene derivative exhibits high carrier mobility and reduced change in threshold voltage after driven repeatedly.    DETAILED DESCRIPTION - A naphthalene derivative of formula (I-1) or (I-2) is new.    X=S or O;    R1-R6=H or substituents, where at least one R1-R6 is substituent of formula (W'): -L-R;    L=bivalent coupling group of formula (L-1)-(L-12) or bivalent coupling group in which two or more bivalent coupling group are bonded;    R=alkyl, trialkylsilyl (both optionally substituted), oligo siloxane having 2 or more silicon atoms, or oligo oxyethylene having two or more of number repeating number of oxyethylene unit;    m=4;    m1=2;and    R'=H or substituents.    (i) When L is group (L-1) and R is optionally substituted alkyl, carbon number of principal chain is three or more; (ii) When L is group (L-2) or (L-3), carbon number of principal chain is two or more; (iii) When L is group (L-4)-(L-12), carbon number of principal chain is four or more; and (iv) When L adjacent to R is bivalent coupling group (L-3), R is optionally substituted trialkylsilyl. INDEPENDENT CLAIMS are included for the following:    (1) organic thin-film transistor comprises semiconductor active layer (14) including naphthalene derivative (1-1) or (1-2);    (2) coating solution containing naphthalene derivative; and    (3) organic-semiconductor thin film containing naphthalene derivative.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the organic thin-film transistor containing the naphthalene derivative.    Substrate (11)    Electrodes (12,15a,15b)    Insulator layer (13)    Semiconductor active layer (14)