PTB7:PC71BM Bulk Heterojunction Solar Cells with Multiple Additives
In this work, active layers were fabricated by spin coating 1,2-dichlorobenzene (500 μl) solutions of PTB7 (5 mg): PC71BM (7.5 mg) containing 0.369 mg (3wt%) of DIO and additional DMSO with different weight ratios to the total weight of PTB7:PC71BM (12.5 mg) from 0 to 30 wt% (0 to 3.69 mg). It was found that the solar cells with 13wt% (1.60 mg) of DMSO additives exhibited the best solar cell performance of an open circuit voltage of 0.72 V, short circuit current density of 15.63 mA/cm2, fill factor of 0.49, and power conversion efficiency of 5.47%. The significant structural changes were found from the surface morphology observations of the active layers depending on the DMSO concentration as observed by atomic force microscope.
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