Organic solar cells of FTO/PEDOT: PSS/P3HT: PCBM/Al has been fabricated, and its performance has been tested in dark and under various illumination of light intensity 1000 W/m 2. The active materials used in this study are poly (3-hexylthiophene)(P3HT) and [6, 6]-phenyl-C 61-butyric acid methyl ester (PCBM). P3HT is the donor while PCBM acts as an acceptor. Variation of PCBM and P3HT are 1: 1, 1: 2, 1: 3, 1: 4 and 1: 5. P3HT: PCBM was mixed by chlorobenzene solvents. The mixing was done by using the ultrasonic cleaner. The absorbance characterization using by UV-Visible Spectrometer Lambda 25 instrument and IV characterization has been tested using a set of 2602A Keithley instrument. Absorbance characterization shows that two peaks are formed. The first peak in the range of 300 to 350 nm which is a range of PCBM and the second peak range from 450 to 600 nm which is a range of P3HT. As the mass ratio increases, the second peak of P3HT increases while the first peak does not change. The gap energy estimated by the Tauc method is 2.0 eV. IV characterization of the efficiency was obtained. The efficiency of sample 1, 2, 3, 4, and 5 are 5.80 x10-2%; 6.46 x10-2%; 7.72 x10-2%; 8.25 x10-2% and 9.81 x10-2%, respectively. The highest value of efficiency was obtained at mass ratio 1: 5.