Fabrication and Characteristics of Organic Thin-film Solar Cells with Active Layer of Interpenetrated Hetero-junction Structure

Interpenetrated hetero-junction structures based on poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5 -b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl] (PTB7)/[6,6]-Phenyl C71 butyric acid methyl ester(PC71BM) were prepared for organic solar cell device fabrication by using wet process combination of spin-coating (PTB7) and spray-coating (PC71BM). Precursor solutions for the wet process of active layers were prepared with 1,8-Diiodooctane(DIO) as additive solvent and four different hetero-junction structures were prepared. Light absorbance and surface morphology for each single layer and hetero-junction structures were investigated by UV-Vis spectrometer and AFM, respectively. J-V characteristics of the resulting organic solar cell devices were measured to evaluate their performance. The interpenetrated hetero-junction structure of PTB7/PC71BM prepared with DIO additive attributed to drastic increase of power conversion efficiency (h=3.54%) from that (h=1.24%) of without DIO additive.