NOVELTY - A cyclohexadiene fullerene derivative (I), is new.    USE - New cyclohexadiene fullerene derivative is used as electron acceptor or n-type semiconductor used in mixture used as semiconducting, charge transport, electroconductive, photoconductive, thermoelectric, or light-emitting material used in formulation used for preparing component e.g. charge-injection layer, charge-transport layer, interlayer, planarizing layer, antistatic film, polymer electrolyte membrane, conducting substrate, and conducting pattern for operating optical, electro-optical, electronic, electroluminescent, or photoluminescent device e.g. organic field effect transistor, organic thin film transistor, organic light-emitting diode, organic light-emitting transistor, bulk heterojunction of bulk heterojunction organic photovoltaic device or inverted bulk heterojunction organic photovoltaic device, organic photodetector, organic solar cell, thermoelectric device, laser diode, Schottky diode, photoconductor and photodetector used for forming assembly e.g. integrated circuit, radio frequency identification tag and security marking of security device, backlight of flat panel display, electrophotographic device, electrophotographic recording device, organic memory device, sensor device e.g. biosensor and biochip (all claimed).    ADVANTAGE - The cyclohexadiene fullerene derivative has excellent solubility with respect to organic solvent, light stability, thermal stability, film-forming property, electronic property, carrier mobility, and processability, and provides organic photovoltaic device with excellent durability, and is manufactured with high productivity.    DETAILED DESCRIPTION - A cyclohexadiene fullerene derivative of formula (I), is new.    Cn=fullerene containing n carbon atoms, optionally containing one or more atoms trapped in inner side;    adduct=secondary adduct bonded to Cn with connectivity;    o,m=1 or more;    R1-R4=H, halo, CN, R5, or R6;    R5=saturated or unsaturated, non-aromatic carbocyclyl or heterocyclyl, or aryl, heteroaryl, aryloxy, or heteroaryloxy containing 3-20 ring atoms (all optionally substituted by halo or CN), which are monocyclic or polycyclic groups optionally containing fused ring;    R6=linear, branched or cyclic 1-30C alkyl, in which CH2 is optionally substituted by -O-, -S-, -C(=O)-, -C(=S)-, -C(=O)-O-, -O-C(=O)-, -NR0-, -C(=O)-NR0-, --NR0-C(=O)-, -SiR0R00-, -CF2-, -CHR0=CR00-, -CY1=CY2- or -CC- such that O and S are not linked directly to each other, and H is optionally substituted by F, Cl, Br, I or CN;    Y1,Y2=H, F, Cl or CN;and    R0,R00=H or optionally substituted 1-40C carbyl or hydrocarbyl.    INDEPENDENT CLAIMS are included for the following:    (1) mixture, which contains 2 or more fullerene derivatives containing cyclohexadiene fullerene derivative; and    (2) formulation, which contains the cyclohexadiene fullerene derivative or the mixture, and an organic solvent.