NOVELTY - A benzo(b)naphtho(2,1-d)furan derivative (I) is new.    USE - New benzo(b)naphtho(2,1-d)furan derivative is used for solar cell, organic light-emitting element and manufacture of field-effect transistor for array used for display apparatus (all claimed) e.g. liquid crystal display device and organic electroluminescent display device.    ADVANTAGE - The benzo(b)naphtho(2,1-d)furan derivative has high storage stability under atmospheric condition.    DETAILED DESCRIPTION - A benzo(b)naphtho(2,1-d)furan derivative of formula (I) is new.    R1-R4=aromatic group, alkoxy, aromatic oxy, alkyl-substituted amino, aromatic-substituted amino, acyl, 1-20C aliphatic hydrocarbyl (all optionally substituted), H, halo, hydroxy, mercapto, nitro or amino;    a,b=0-3;and    c,d=0-6.    INDEPENDENT CLAIMS are included for the following:    (1) field-effect transistor (1A), which has organic semiconductor layer containing the benzo(b)naphtho(2,1-d)furan derivative (I);    (2) manufacture of field-effect transistor, which involves forming organic semiconductor layer by dip coating, coating method and printing method using composition containing the benzo(b)naphtho(2,1-d)furan derivative (I), and toluene, chlorobenzene, dichlorobenzene, trichlorobenzene, dichloromethane and/or chloroform;    (3) solar cell, which has organic semiconductor layer containing the benzo(b)naphtho(2,1-d)furan derivative (I);    (4) organic light-emitting element, which has carrier transport layer containing the benzo(b)naphtho(2,1-d)furan derivative (I);    (5) composition for forming organic semiconductor layer of field-effect transistor, which contains the benzo(b)naphtho(2,1-d)furan derivative (I);    (6) composition for forming carrier transport layer of the organic light-emitting element, which contains the benzo(b)naphtho(2,1-d)furan derivative (I);    (7) array, which has the field-effect transistor as a switching element; and    (8) display apparatus, which has image-signal output component which generates and sends an image signal, drive component which generates an electric current or a voltage based on the image signal, and light-emission component which emits light using the generated electric current or voltage. The light-emission component is organic light-emitting element.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the field-effect transistor manufactured using the benzo(b)naphtho(2,1-d)furan derivative.    Field-effect transistor (1A)    Gate electrode (12)    Gate insulating film (13)    Source electrode (14)    Drain electrode (15)    Organic semiconductor layer (16)