TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The composition comprises 0-2 (preferably 0-0.5) mol.% mono-adduct fullerene derivative(s), 0-2 (preferably 0-0.5) mol.% tris-adduct fullerene derivative(s), and 0-2 (preferably 0-0.5) mol.% multi-adduct fullerene derivative(s). The bis-adduct fullerene derivatives are bis-(60) (6,6)-phenyl 61C butyric acid methyl ester (PCBM) or bis-(70)PCBM. The tris-adduct fullerene derivatives are tris-(60)PCBM or tris-(70)PCBM. Tetra-adduct fullerene derivatives are tetra-(60)PCBM or tetra-(70)PCBM. Penta-adduct fullerene derivatives are penta-(60)PCBM or penta-(70)PCBM. Hexa-adduct fullerene derivatives are hexa-(60)PCBM or hexa-(70)PCBM. The bis-adduct fullerene derivatives are bis-methanofullerene. The tris-adduct fullerene derivatives are tris-methanofullerene. The tetra-adduct fullerene derivatives are tetra-methanofullerene. The penta-adduct fullerene derivatives are penta-methanofullerene. The hexa-adduct fullerene derivatives are hexa-methanofullerene. The multi-adduct fullerene derivatives are methanofullerenes. The bis-adduct fullerene derivatives are a combination of bis-(60)methanofullerene and bis-(70)methanofullerene. The tris-adduct fullerene derivatives are a combination of tris-(60)methanofullerene and tris-(70)methanofullerene. The tetra-adduct fullerene derivatives are a combination of tetra-(60)methanofullerene and tetra-(70)methanofullerene. The penta-adduct fullerene derivatives are a combination of penta-(60)methanofullerene and penta-(70)methanofullerene. The hexa-adduct fullerene derivatives are a combination of hexa-(60)methanofullerene and hexa-(70)methanofullerene. The multi-adduct fullerene derivatives are a combination of multi-adduct-(60)methanofullerene and multi-adduct-(70)methanofullerene. The fullerene derivatives are methanofullerene derivatives, Prato fullerene derivatives, Diels-Alder fullerene derivatives, diazoline fullerene derivatives, Bingel fullerene derivatives, ketolactam fullerene derivatives, or azafulleroid fullerene derivatives. The fullerene derivatives are derivatives of C60 or derivatives of C70. The bis-adduct fullerene derivatives are bis-(60)PCBM fullerene derivative, bis-(70)PCBM fullerene derivative, bis-(60)ThCBM fullerene derivative, bis-(70)ThCBM fullerene derivative, 3,4-OMe-(60)PCBM bis-adduct, 3,4-OMe-(70)PCBM bis adduct, bis(60)PCB-C4, bis(70)PCB-C4, bis(60)PCB-C8, bis(70)PCB-C8, mono-methoxy-mono- (60)PCBM, or mono-methoxy-mono-(70)PCBM. EXAMPLE - No suitable example given.