Band-Tail Transport of CuSCN: Origin of Hole Extraction Enhancement in Organic Photovoltaics

Minju Kim, Soohyung Park, Junkyeong Jeong, Dongguen Shin, Jimin Kim, Sae Hee Ryu, Keun Su Kim, Hyunbok Lee, Yeonjin Yi

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Copper thiocyanate (CuSCN) is known as a promising hole transport layer in organic photovoltaics (OPVs) due to its good hole conduction and exciton blocking abilities with high transparency. Despite its successful device applications, the origin of its hole extraction enhancement in OPVs has not yet been understood. Here, we investigated the electronic structure of CuSCN and the energy level alignment at the poly(3-hexylthiophene-2,5-diyl) (P3HT)/CuSCN/ITO interfaces using ultraviolet photoelectron spectroscopy. The band-tail states of CuSCN close to the Fermi level (EF) were observed at 0.25 eV below the EF, leading to good hole transport. The CuSCN interlayer significantly reduces the hole transport barrier between ITO and P3HT due to its high work function and band-tail states. The barrier reduction leads to enhanced current density-voltage characteristics of hole-dominated devices. These results provide the origin of hole-extraction enhancement by CuSCN and insights for further application.

Original languageEnglish
Pages (from-to)2856-2861
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume7
Issue number14
DOIs
Publication statusPublished - 2016 Jul 21

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Ultraviolet photoelectron spectroscopy
augmentation
Fermi level
Excitons
Transparency
Electron energy levels
Electronic structure
Current density
Copper
ITO (semiconductors)
Electric potential
ultraviolet spectroscopy
cuprous thiocyanate
interlayers
energy levels
alignment
excitons
photoelectron spectroscopy
current density
electronic structure

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physical and Theoretical Chemistry

Cite this

Kim, Minju ; Park, Soohyung ; Jeong, Junkyeong ; Shin, Dongguen ; Kim, Jimin ; Ryu, Sae Hee ; Kim, Keun Su ; Lee, Hyunbok ; Yi, Yeonjin. / Band-Tail Transport of CuSCN : Origin of Hole Extraction Enhancement in Organic Photovoltaics. In: Journal of Physical Chemistry Letters. 2016 ; Vol. 7, No. 14. pp. 2856-2861.
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Band-Tail Transport of CuSCN : Origin of Hole Extraction Enhancement in Organic Photovoltaics. / Kim, Minju; Park, Soohyung; Jeong, Junkyeong; Shin, Dongguen; Kim, Jimin; Ryu, Sae Hee; Kim, Keun Su; Lee, Hyunbok; Yi, Yeonjin.

In: Journal of Physical Chemistry Letters, Vol. 7, No. 14, 21.07.2016, p. 2856-2861.

Research output: Contribution to journalArticle

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AU - Kim, Minju

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AU - Jeong, Junkyeong

AU - Shin, Dongguen

AU - Kim, Jimin

AU - Ryu, Sae Hee

AU - Kim, Keun Su

AU - Lee, Hyunbok

AU - Yi, Yeonjin

PY - 2016/7/21

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N2 - Copper thiocyanate (CuSCN) is known as a promising hole transport layer in organic photovoltaics (OPVs) due to its good hole conduction and exciton blocking abilities with high transparency. Despite its successful device applications, the origin of its hole extraction enhancement in OPVs has not yet been understood. Here, we investigated the electronic structure of CuSCN and the energy level alignment at the poly(3-hexylthiophene-2,5-diyl) (P3HT)/CuSCN/ITO interfaces using ultraviolet photoelectron spectroscopy. The band-tail states of CuSCN close to the Fermi level (EF) were observed at 0.25 eV below the EF, leading to good hole transport. The CuSCN interlayer significantly reduces the hole transport barrier between ITO and P3HT due to its high work function and band-tail states. The barrier reduction leads to enhanced current density-voltage characteristics of hole-dominated devices. These results provide the origin of hole-extraction enhancement by CuSCN and insights for further application.

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