The origin of high PCE in PTB7 based photovoltaics: Proper charge neutrality level and free energy of charge separation at PTB7/PC 71 BM interface

Soohyung Park, Junkyeong Jeong, Gyeongho Hyun, Minju Kim, Hyunbok Lee, Yeonjin Yi

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The energy level alignments at donor/acceptor interfaces in organic photovoltaics (OPVs) play a decisive role in device performance. However, little is known about the interfacial energetics in polymer OPVs due to technical issues of the solution process. Here, the frontier ortbial line-ups at the donor/acceptor interface in high performance polymer OPVs, PTB7/PC 71 BM, were investigated using in situ UPS, XPS and IPES. The evolution of energy levels during PTB7/PC 71 BM interface formation was investigated using vacuum electrospray deposition, and was compared with that of P3HT/PC 61 BM. At the PTB7/PC 71 BM interface, the interface dipole and the band bending were absent due to their identical charge neutrality levels. In contrast, a large interfacial dipole was observed at the P3HT/PC 61 BM interface. The measured photovoltaic energy gap (E PVG ) was 1.10 eV for PTB7/PC 71 BM and 0.90 eV for P3HT/PC 61 BM. This difference in the E PVG leads to a larger open-circuit voltage of PTB7/PC 71 BM than that of P3HT/PC 61 BM.

Original languageEnglish
Article number35262
JournalScientific reports
Volume6
DOIs
Publication statusPublished - 2016 Oct 13

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polarization (charge separation)
energy levels
free energy
dipoles
vacuum deposition
polymers
open circuit voltage
alignment

All Science Journal Classification (ASJC) codes

  • General

Cite this

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title = "The origin of high PCE in PTB7 based photovoltaics: Proper charge neutrality level and free energy of charge separation at PTB7/PC 71 BM interface",
abstract = "The energy level alignments at donor/acceptor interfaces in organic photovoltaics (OPVs) play a decisive role in device performance. However, little is known about the interfacial energetics in polymer OPVs due to technical issues of the solution process. Here, the frontier ortbial line-ups at the donor/acceptor interface in high performance polymer OPVs, PTB7/PC 71 BM, were investigated using in situ UPS, XPS and IPES. The evolution of energy levels during PTB7/PC 71 BM interface formation was investigated using vacuum electrospray deposition, and was compared with that of P3HT/PC 61 BM. At the PTB7/PC 71 BM interface, the interface dipole and the band bending were absent due to their identical charge neutrality levels. In contrast, a large interfacial dipole was observed at the P3HT/PC 61 BM interface. The measured photovoltaic energy gap (E PVG ) was 1.10 eV for PTB7/PC 71 BM and 0.90 eV for P3HT/PC 61 BM. This difference in the E PVG leads to a larger open-circuit voltage of PTB7/PC 71 BM than that of P3HT/PC 61 BM.",
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The origin of high PCE in PTB7 based photovoltaics : Proper charge neutrality level and free energy of charge separation at PTB7/PC 71 BM interface. / Park, Soohyung; Jeong, Junkyeong; Hyun, Gyeongho; Kim, Minju; Lee, Hyunbok; Yi, Yeonjin.

In: Scientific reports, Vol. 6, 35262, 13.10.2016.

Research output: Contribution to journalArticle

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AU - Yi, Yeonjin

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