8.9% single-stack inverted polymer solar cells with electron-rich polymer nanolayer-modified inorganic electron-collecting buffer layers

Sungho Woo, Wook Hyun Kim, Hwajeong Kim, Yeonjin Yi, Hong Kun Lyu, Youngkyoo Kim

Research output: Contribution to journalArticle

181 Citations (Scopus)

Abstract

Enhanced power conversion efficiency (PCE) is reported in inverted polymer solar cells when an electron-rich polymer nanolayer (poly(ethyleneimine) (PEI)) is placed on the surface of an electron-collecting buffer layer (ZnO). The active layer is made with bulk heterojunction films of poly[[4,8-bis[(2- ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The thickness of the PEI nanolayer is controlled to be 2 nm to minimize its insulating effect, which is confirmed by X-ray photoelectron spectroscopy and optical absorption measurements. The Kelvin probe and ultraviolet photoelectron spectroscopy measurements demonstrate that the enhanced PCE by introducing the PEI nanolayer is attributed to the lowered conduction band energy of the ZnO layer via the formation of an interfacial dipole layer at the interfaces between the ZnO layer and the PEI nanolayer. The PEI nanolayer also improves the surface roughness of the ZnO layer so that the device series resistance can be noticeably decreased. As a result, all solar cell parameters including short circuit current density, open circuit voltage, fill factor, and shunt resistance are improved, leading to the PCE increase up to ≈8.9%, which is close to the best PCE reported using conjugated polymer electrolyte films. 8.9% power conversion efficiency is achieved using inverted-type polymer:fullerene solar cells. 2 nm-thick electron-rich poly(ethyleneimine) nanolayers are placed on the ZnO electron-collecting buffer layers and the increased built-in electric field caused by the lowered conduction band energy of ZnO layers enhances performance.

Original languageEnglish
Article number1301692
JournalAdvanced Energy Materials
Volume4
Issue number7
DOIs
Publication statusPublished - 2014 May 13

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Buffer layers
Conversion efficiency
Polymers
Electrons
Conduction bands
Solar cells
Ultraviolet photoelectron spectroscopy
Butyric acid
Fullerenes
Conjugated polymers
Open circuit voltage
Butyric Acid
R Factors
Short circuit currents
Light absorption
Heterojunctions
Esters
Current density
X ray photoelectron spectroscopy
Electrolytes

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

Cite this

@article{858378b10cc04ebea5d83ebda2f1ab1a,
title = "8.9{\%} single-stack inverted polymer solar cells with electron-rich polymer nanolayer-modified inorganic electron-collecting buffer layers",
abstract = "Enhanced power conversion efficiency (PCE) is reported in inverted polymer solar cells when an electron-rich polymer nanolayer (poly(ethyleneimine) (PEI)) is placed on the surface of an electron-collecting buffer layer (ZnO). The active layer is made with bulk heterojunction films of poly[[4,8-bis[(2- ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The thickness of the PEI nanolayer is controlled to be 2 nm to minimize its insulating effect, which is confirmed by X-ray photoelectron spectroscopy and optical absorption measurements. The Kelvin probe and ultraviolet photoelectron spectroscopy measurements demonstrate that the enhanced PCE by introducing the PEI nanolayer is attributed to the lowered conduction band energy of the ZnO layer via the formation of an interfacial dipole layer at the interfaces between the ZnO layer and the PEI nanolayer. The PEI nanolayer also improves the surface roughness of the ZnO layer so that the device series resistance can be noticeably decreased. As a result, all solar cell parameters including short circuit current density, open circuit voltage, fill factor, and shunt resistance are improved, leading to the PCE increase up to ≈8.9{\%}, which is close to the best PCE reported using conjugated polymer electrolyte films. 8.9{\%} power conversion efficiency is achieved using inverted-type polymer:fullerene solar cells. 2 nm-thick electron-rich poly(ethyleneimine) nanolayers are placed on the ZnO electron-collecting buffer layers and the increased built-in electric field caused by the lowered conduction band energy of ZnO layers enhances performance.",
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8.9% single-stack inverted polymer solar cells with electron-rich polymer nanolayer-modified inorganic electron-collecting buffer layers. / Woo, Sungho; Hyun Kim, Wook; Kim, Hwajeong; Yi, Yeonjin; Lyu, Hong Kun; Kim, Youngkyoo.

In: Advanced Energy Materials, Vol. 4, No. 7, 1301692, 13.05.2014.

Research output: Contribution to journalArticle

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AB - Enhanced power conversion efficiency (PCE) is reported in inverted polymer solar cells when an electron-rich polymer nanolayer (poly(ethyleneimine) (PEI)) is placed on the surface of an electron-collecting buffer layer (ZnO). The active layer is made with bulk heterojunction films of poly[[4,8-bis[(2- ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The thickness of the PEI nanolayer is controlled to be 2 nm to minimize its insulating effect, which is confirmed by X-ray photoelectron spectroscopy and optical absorption measurements. The Kelvin probe and ultraviolet photoelectron spectroscopy measurements demonstrate that the enhanced PCE by introducing the PEI nanolayer is attributed to the lowered conduction band energy of the ZnO layer via the formation of an interfacial dipole layer at the interfaces between the ZnO layer and the PEI nanolayer. The PEI nanolayer also improves the surface roughness of the ZnO layer so that the device series resistance can be noticeably decreased. As a result, all solar cell parameters including short circuit current density, open circuit voltage, fill factor, and shunt resistance are improved, leading to the PCE increase up to ≈8.9%, which is close to the best PCE reported using conjugated polymer electrolyte films. 8.9% power conversion efficiency is achieved using inverted-type polymer:fullerene solar cells. 2 nm-thick electron-rich poly(ethyleneimine) nanolayers are placed on the ZnO electron-collecting buffer layers and the increased built-in electric field caused by the lowered conduction band energy of ZnO layers enhances performance.

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