Three-Phase Morphology Evolution in Sequentially Solution-Processed Polymer Photodetector: Toward Low Dark Current and High Photodetectivity

Hanyu Wang, Shen Xing, Yifan Zheng, Jaemin Kong, Junsheng Yu, Andre Taylor

Research output: Contribution to journalArticle

Abstract

Sequentially solution-processed polymer photodetectors (SSP PPDs) based on poly(3-hexylthiophene-2,5-diyl) (P3HT)/[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) are fabricated by depositing the top layers of PC71BM from an appropriate cosolvent of 2-chlorophenol (2-CP)/o-dichlorobenzene (ODCB) onto the predeposited bottom layers of P3HT. By adjusting the ratio of 2-CP/ODCB in the top PC71BM layers, the resulting SSP PPD shows a decreased dark current and an increased photocurrent, leading to a maximum detectivity of 1.23 × 1012 Jones at a wavelength of 550 nm. This value is 5.3-fold higher than that of the conventional bulk heterojunction PPD. Morphology studies reveal that the PC71BM partially penetrates the predeposited P3HT layer during the spin-coating process, resulting in an optimal three-phase morphology with one well-mixed interdiffusion P3HT/PC71BM phase in the middle of the bulk and two pure phases of P3HT and PC71BM at the two electrode sides. We show that the pure phases form high Schottky barriers (>2.0 eV) at the active layer/electrodes interface and efficiently block unfavorable reverse charge carrier injection by significantly decreasing the dark current. The interdiffussion phase enlarges the donor-acceptor interfacial area leading to a large photocurrent. We also reveal that the improved performance of SSP PPDs is also due to the enhanced optical absorption, improved P3HT crystallinity, increased charge carrier mobilities, and suppressed bimolecular recombination.

Original languageEnglish (US)
Pages (from-to)3856-3864
Number of pages9
JournalACS Applied Materials and Interfaces
Volume10
Issue number4
DOIs
StatePublished - Jan 31 2018

Fingerprint

Butyric acid
Butyric Acid
Dark currents
Photodetectors
Esters
Polymers
Charge carriers
Photocurrents
Electrodes
Carrier mobility
Tuberculin
Spin coating
Light absorption
Heterojunctions
Wavelength

Keywords

  • cosolvent
  • P3HT/PCBM
  • polymer photodetectors (PPDs)
  • sequentially solution-processed
  • three-phase morphology

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Three-Phase Morphology Evolution in Sequentially Solution-Processed Polymer Photodetector : Toward Low Dark Current and High Photodetectivity. / Wang, Hanyu; Xing, Shen; Zheng, Yifan; Kong, Jaemin; Yu, Junsheng; Taylor, Andre.

In: ACS Applied Materials and Interfaces, Vol. 10, No. 4, 31.01.2018, p. 3856-3864.

Research output: Contribution to journalArticle

Wang, Hanyu ; Xing, Shen ; Zheng, Yifan ; Kong, Jaemin ; Yu, Junsheng ; Taylor, Andre. / Three-Phase Morphology Evolution in Sequentially Solution-Processed Polymer Photodetector : Toward Low Dark Current and High Photodetectivity. In: ACS Applied Materials and Interfaces. 2018 ; Vol. 10, No. 4. pp. 3856-3864.
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abstract = "Sequentially solution-processed polymer photodetectors (SSP PPDs) based on poly(3-hexylthiophene-2,5-diyl) (P3HT)/[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) are fabricated by depositing the top layers of PC71BM from an appropriate cosolvent of 2-chlorophenol (2-CP)/o-dichlorobenzene (ODCB) onto the predeposited bottom layers of P3HT. By adjusting the ratio of 2-CP/ODCB in the top PC71BM layers, the resulting SSP PPD shows a decreased dark current and an increased photocurrent, leading to a maximum detectivity of 1.23 × 1012 Jones at a wavelength of 550 nm. This value is 5.3-fold higher than that of the conventional bulk heterojunction PPD. Morphology studies reveal that the PC71BM partially penetrates the predeposited P3HT layer during the spin-coating process, resulting in an optimal three-phase morphology with one well-mixed interdiffusion P3HT/PC71BM phase in the middle of the bulk and two pure phases of P3HT and PC71BM at the two electrode sides. We show that the pure phases form high Schottky barriers (>2.0 eV) at the active layer/electrodes interface and efficiently block unfavorable reverse charge carrier injection by significantly decreasing the dark current. The interdiffussion phase enlarges the donor-acceptor interfacial area leading to a large photocurrent. We also reveal that the improved performance of SSP PPDs is also due to the enhanced optical absorption, improved P3HT crystallinity, increased charge carrier mobilities, and suppressed bimolecular recombination.",
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