MEHPPV:PCBM-based Bulk Heterojunction Organic Solar Cell Blended with Various Organic Salts

摘要

The objective of the experiment is to investigate the effect of different types of organic salt, namely tetrabutylammonium hexafluorophosphate (TBAPF_6), tetrabutylammonium perchlorate (TBAClO_4) and tetrabutylammonium iodide (TBAI) on the performance of organic solar cell with ITO/MEHPPV:PCBM/Al structure, where poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV) acted as donor and (6,6)-phenyl-C61 butyric acid methyl ester (PCBM) as acceptor. The 20 wt% of TBAPF_6, TBAClO_4 and TBAI-blended MEHPPV:PCBM thin films were spin coated onto the ITO, followed by deposition of Al by electron gun evaporation technique. A control device without organic salt was also fabricated for comparison. The performance of the devices was analyzed through the current-voltage (I-V) curve under illumination with a solar simulator AM 1.5 G sunlight at 100 mW/cm~2. Electric field treatment was given by applying the constant voltage of 8 V for 60 s to the device before the I-V characterization. The TBAPF_6-blended device exhibited the highest power conversion efficiency of 0.16 % followed by TBAClO_4-blended and TBAI-blended devices with power conversion efficiency of 0.07 % and 0.002 %, respectively. The smallest power conversion efficiency obtained for TBAI-blended device could be attributed to the reduced number of separated organic salt ions at the photoactive layer-electrode interface as a result of agglomeration of TBAI and stronger ionic bonding of TBAI with smallest anion size.