Abstract
In this study, we found that the formation of a p-i-n junction through in situ electrochemical doping is a promising way to enhance the performance of polymer photovoltaic devices. We applied a pre-bias to metal triflate [LiOTf, KOTf, Ca(OTf)2, Zn(OTf)2]/poly(ethylene oxide) (PEO)-incorporated poly[5-(2′-ethylhexyloxy)-2-methoxy-1,4- phenylenevinylene] (MEH-PPV)/{6}-1-(3-(methoxycarbonyl)propyl)-{5}-1-phenyl-[5, 6]-C61 (PCBM) photovoltaic devices to form p-i-n junctions in their active layers. Auger depth profile analyses and alternating-current capacitance analyses of these doped devices revealed that the positive and negative ions were distributed unequally to form an asymmetrical p-i-n structure in a thin layer of ca. 100 nm of the polymer, and the intrinsic layer became thinner when formed under a higher pre-bias voltage. Atomic force microscopy and transmission electron microscopy revealed that the addition of metal triflate/PEO to MEH-PPV/PCBM improved the morphology of the composite films. Among the various doped devices, the MEH-PPV/PCBM device incorporating a LiOTf/PEO mixture exhibited the highest power conversion efficiency, a 40% increase relative to that of the reference device (MEH-PPV/PCBM).
Original language | English |
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Pages (from-to) | 6217-6224 |
Number of pages | 8 |
Journal | Journal of Materials Chemistry |
Volume | 21 |
Issue number | 17 |
DOIs | |
State | Published - 7 May 2011 |