Solution-processed annealing-free ZnO nanoparticles for stable inverted organic solar cells

S. Alem, J. Lu (Corresponding Author), R. Movileanu, Terho Kololuoma, A. Dadvand, Y. Tao (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

18 Citations (Scopus)

Abstract

We report the development and application of high-quality zinc oxide nanoparticles (ZnO NPs) processed in air for stable inverted bulk heterojunction solar cells as an electron extraction layer (EEL). The ZnO NPs (average size ~11 nm) were dispersed in chloroform and stabilized by propylamine (PA). We demonstrated that the ZnO NP dispersion with 4 vol.% of PA as stabilizer can be used in air directly and remains clear up to one month after preparation. Our inverted solar cells consisted of a blade-coated poly(N-9'-heptadecanyl-2, 7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1', 3'-benzothiadiazole (PCDTBT) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) (1: 4 by weight) active layer sandwiched between a ZnO electron extraction layer and a MoO3/Ag anode. All solar cells with ZnO films fabricated in air using PA-stabilized ZnO dispersions prepared within a time window of one month exhibited power conversion efficiencies (PCE) above 4%. In contrast, if the ZnO film was prepared in air using regular un-stabilized ZnO NP dispersion, the PCE would drop to 0.2% due to poor film quality. More interestingly, X-ray photoelectron spectroscopy and nuclear magnetic resonance measurements indicated that the PA ligands were not covalently bonded to ZnO NPs and did not exist in the deposited ZnO films. The spin-cast ZnO thin films (without any thermal treatment) are insoluble in organic solvents and can be directly used as an EEL in solar cells. This feature is beneficial for fabricating organic solar cells on flexible polymer substrates. More importantly, our non-encapsulated inverted solar cells are highly stable with their PCEs remaining unchanged after being stored in air for 50 days.
Original languageEnglish
Pages (from-to)1035-1042
Number of pages7
JournalOrganic Electronics
Volume15
Issue number5
DOIs
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed

Fingerprint

Zinc Oxide
Propylamines
Zinc oxide
Solar cells
zinc oxides
solar cells
Annealing
Nanoparticles
nanoparticles
annealing
Air
air
Conversion efficiency
Electrons
Magnetic resonance measurement
Butyric acid
Butyric Acid
Chloroform
Chlorine compounds
electrons

Keywords

  • Bulk heterojunction
  • inverted solar cell
  • propylamine
  • stability
  • zinc oxide nanoparticles

Cite this

Alem, S. ; Lu, J. ; Movileanu, R. ; Kololuoma, Terho ; Dadvand, A. ; Tao, Y. / Solution-processed annealing-free ZnO nanoparticles for stable inverted organic solar cells. In: Organic Electronics. 2014 ; Vol. 15, No. 5. pp. 1035-1042.
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abstract = "We report the development and application of high-quality zinc oxide nanoparticles (ZnO NPs) processed in air for stable inverted bulk heterojunction solar cells as an electron extraction layer (EEL). The ZnO NPs (average size ~11 nm) were dispersed in chloroform and stabilized by propylamine (PA). We demonstrated that the ZnO NP dispersion with 4 vol.{\%} of PA as stabilizer can be used in air directly and remains clear up to one month after preparation. Our inverted solar cells consisted of a blade-coated poly(N-9'-heptadecanyl-2, 7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1', 3'-benzothiadiazole (PCDTBT) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) (1: 4 by weight) active layer sandwiched between a ZnO electron extraction layer and a MoO3/Ag anode. All solar cells with ZnO films fabricated in air using PA-stabilized ZnO dispersions prepared within a time window of one month exhibited power conversion efficiencies (PCE) above 4{\%}. In contrast, if the ZnO film was prepared in air using regular un-stabilized ZnO NP dispersion, the PCE would drop to 0.2{\%} due to poor film quality. More interestingly, X-ray photoelectron spectroscopy and nuclear magnetic resonance measurements indicated that the PA ligands were not covalently bonded to ZnO NPs and did not exist in the deposited ZnO films. The spin-cast ZnO thin films (without any thermal treatment) are insoluble in organic solvents and can be directly used as an EEL in solar cells. This feature is beneficial for fabricating organic solar cells on flexible polymer substrates. More importantly, our non-encapsulated inverted solar cells are highly stable with their PCEs remaining unchanged after being stored in air for 50 days.",
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Solution-processed annealing-free ZnO nanoparticles for stable inverted organic solar cells. / Alem, S.; Lu, J. (Corresponding Author); Movileanu, R.; Kololuoma, Terho; Dadvand, A.; Tao, Y. (Corresponding Author).

In: Organic Electronics, Vol. 15, No. 5, 2014, p. 1035-1042.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Solution-processed annealing-free ZnO nanoparticles for stable inverted organic solar cells

AU - Alem, S.

AU - Lu, J.

AU - Movileanu, R.

AU - Kololuoma, Terho

AU - Dadvand, A.

AU - Tao, Y.

PY - 2014

Y1 - 2014

N2 - We report the development and application of high-quality zinc oxide nanoparticles (ZnO NPs) processed in air for stable inverted bulk heterojunction solar cells as an electron extraction layer (EEL). The ZnO NPs (average size ~11 nm) were dispersed in chloroform and stabilized by propylamine (PA). We demonstrated that the ZnO NP dispersion with 4 vol.% of PA as stabilizer can be used in air directly and remains clear up to one month after preparation. Our inverted solar cells consisted of a blade-coated poly(N-9'-heptadecanyl-2, 7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1', 3'-benzothiadiazole (PCDTBT) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) (1: 4 by weight) active layer sandwiched between a ZnO electron extraction layer and a MoO3/Ag anode. All solar cells with ZnO films fabricated in air using PA-stabilized ZnO dispersions prepared within a time window of one month exhibited power conversion efficiencies (PCE) above 4%. In contrast, if the ZnO film was prepared in air using regular un-stabilized ZnO NP dispersion, the PCE would drop to 0.2% due to poor film quality. More interestingly, X-ray photoelectron spectroscopy and nuclear magnetic resonance measurements indicated that the PA ligands were not covalently bonded to ZnO NPs and did not exist in the deposited ZnO films. The spin-cast ZnO thin films (without any thermal treatment) are insoluble in organic solvents and can be directly used as an EEL in solar cells. This feature is beneficial for fabricating organic solar cells on flexible polymer substrates. More importantly, our non-encapsulated inverted solar cells are highly stable with their PCEs remaining unchanged after being stored in air for 50 days.

AB - We report the development and application of high-quality zinc oxide nanoparticles (ZnO NPs) processed in air for stable inverted bulk heterojunction solar cells as an electron extraction layer (EEL). The ZnO NPs (average size ~11 nm) were dispersed in chloroform and stabilized by propylamine (PA). We demonstrated that the ZnO NP dispersion with 4 vol.% of PA as stabilizer can be used in air directly and remains clear up to one month after preparation. Our inverted solar cells consisted of a blade-coated poly(N-9'-heptadecanyl-2, 7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1', 3'-benzothiadiazole (PCDTBT) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) (1: 4 by weight) active layer sandwiched between a ZnO electron extraction layer and a MoO3/Ag anode. All solar cells with ZnO films fabricated in air using PA-stabilized ZnO dispersions prepared within a time window of one month exhibited power conversion efficiencies (PCE) above 4%. In contrast, if the ZnO film was prepared in air using regular un-stabilized ZnO NP dispersion, the PCE would drop to 0.2% due to poor film quality. More interestingly, X-ray photoelectron spectroscopy and nuclear magnetic resonance measurements indicated that the PA ligands were not covalently bonded to ZnO NPs and did not exist in the deposited ZnO films. The spin-cast ZnO thin films (without any thermal treatment) are insoluble in organic solvents and can be directly used as an EEL in solar cells. This feature is beneficial for fabricating organic solar cells on flexible polymer substrates. More importantly, our non-encapsulated inverted solar cells are highly stable with their PCEs remaining unchanged after being stored in air for 50 days.

KW - Bulk heterojunction

KW - inverted solar cell

KW - propylamine

KW - stability

KW - zinc oxide nanoparticles

U2 - 10.1016/j.orgel.2014.02.024

DO - 10.1016/j.orgel.2014.02.024

M3 - Article

VL - 15

SP - 1035

EP - 1042

JO - Organic Electronics

JF - Organic Electronics

SN - 1566-1199

IS - 5

ER -