In situ electrochemical doping enhances the efficiency of polymer photovoltaic devices

Ming Shin Su, Hai-Ching Su, Chih Yin Kuo, Yi Ren Zhou, Kung-Hwa Wei*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

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 languageEnglish
Pages (from-to)6217-6224
Number of pages8
JournalJournal of Materials Chemistry
Volume21
Issue number17
DOIs
StatePublished - 7 May 2011

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