Organic solar cell and method for fabricating the same

An organic solar cell comprising:

• a lower electrode formed on a substrate;
• a photoactive layer formed on the lower electrode and comprising (a) a p-type organic semiconductor material, (b) an n-type organic semiconductor material, and (c) a solvent;
• and an upper electrode formed on the photoactive layer wherein the p-type organic semiconductor material (a) comprises (a-1) a first organic semiconductor material represented by Formula 1:
• wherein X1, X2, X3, and X4 are the same or different and are each independently hydrogen or a halogen and R1, R2, R3, and R4 are the same or different and are each independently a C1-C22 linear or branched alkyl group, and (a-2) a second organic semiconductor material represented by Formula 2:
• wherein R5 and R6 are the same or different and are each independently H or a C1-C22 linear or branched alkyl group, n is an integer from 1 to 10,000,000, and Ar is selected from aromatic groups having the following structures 2a:
• wherein R7, R8, R9, and R10 are the same or different and are each independently H or a C1-C22 linear or branched alkyl group.