Charge selectivity in polymer:Fullerene-based organic solar cells with a chemically linked polyethylenimine interlayer

Fu Chiao Wu, Kuo Cheng Tung, Wei Yang Chou, Fu-Ching Tang, Horng Long Cheng

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The power conversion efficiency of solar cells can be optimized via an efficient charge collection by electrodes. In this study, a simple linear polyethylenimine (LPEI), which is an insulating polymer, was adopted as the cathode interfacial layer of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-based bulk-heterojunction organic solar cells (OSCs) with a non-inverted configuration. All photovoltaic parameters of the OSCs were significantly enhanced by depositing LPEI onto the oxygen plasma-treated P3HT:PCBM active layers. The causes of performance enhancement in OSCs were studied. Results revealed that the microstructure and morphology of the P3HT:PCBM layer were almost unaffected by the oxygen plasma treatment and the subsequent LPEI deposition. The X-ray photoelectron spectra of the specimens demonstrated that with the aid of oxygen plasma treatment, the linked LPEI molecules formed a well-aligned dipole layer on top of the P3HT:PCBM layer through the bonding of nitrogen (N) with oxygen (O). The results from quantum chemical calculations showed that the LPEI molecule with an N-O bond had a larger dipole moment at an appropriate direction than that without an N-O bond. By contrast, the LPEI molecules can form a dipole layer with a random orientation in the absence of N-O bonds. The conductive atomic force microscopy images of the specimens showed that the well-aligned dipole layer could facilitate electron transfer and could block hole transfer from the P3HT:PCBM to the cathodes. The well-aligned and augmented interface dipoles improved the charge selectivity at the cathodes and the photovoltaic performance of the devices.

Original languageEnglish
Pages (from-to)120-126
Number of pages7
JournalOrganic Electronics
Volume29
DOIs
Publication statusPublished - 2016 Feb 1

Fingerprint

Fullerenes
Polyethyleneimine
Butyric acid
fullerenes
interlayers
butyric acid
Esters
Polymers
Butyric Acid
solar cells
selectivity
esters
polymers
Cathodes
Oxygen
oxygen plasma
Plasmas
dipoles
Molecules
cathodes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering

Cite this

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abstract = "The power conversion efficiency of solar cells can be optimized via an efficient charge collection by electrodes. In this study, a simple linear polyethylenimine (LPEI), which is an insulating polymer, was adopted as the cathode interfacial layer of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-based bulk-heterojunction organic solar cells (OSCs) with a non-inverted configuration. All photovoltaic parameters of the OSCs were significantly enhanced by depositing LPEI onto the oxygen plasma-treated P3HT:PCBM active layers. The causes of performance enhancement in OSCs were studied. Results revealed that the microstructure and morphology of the P3HT:PCBM layer were almost unaffected by the oxygen plasma treatment and the subsequent LPEI deposition. The X-ray photoelectron spectra of the specimens demonstrated that with the aid of oxygen plasma treatment, the linked LPEI molecules formed a well-aligned dipole layer on top of the P3HT:PCBM layer through the bonding of nitrogen (N) with oxygen (O). The results from quantum chemical calculations showed that the LPEI molecule with an N-O bond had a larger dipole moment at an appropriate direction than that without an N-O bond. By contrast, the LPEI molecules can form a dipole layer with a random orientation in the absence of N-O bonds. The conductive atomic force microscopy images of the specimens showed that the well-aligned dipole layer could facilitate electron transfer and could block hole transfer from the P3HT:PCBM to the cathodes. The well-aligned and augmented interface dipoles improved the charge selectivity at the cathodes and the photovoltaic performance of the devices.",
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Charge selectivity in polymer:Fullerene-based organic solar cells with a chemically linked polyethylenimine interlayer. / Wu, Fu Chiao; Tung, Kuo Cheng; Chou, Wei Yang; Tang, Fu-Ching; Cheng, Horng Long.

In: Organic Electronics, Vol. 29, 01.02.2016, p. 120-126.

Research output: Contribution to journalArticle

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AU - Cheng, Horng Long

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