Sputter-Deposited Titanium Oxide Layers as Efficient Electron Selective Contacts in Organic Photovoltaic Devices

Mina Mirsafaei; Pia Bomholt Jensen; Mehrad Ahmadpour; Harish Lakhotiya; John Lundsgaard Hansen; Brian Julsgaard; Horst Günter Rubahn; Rémi Lazzari; Nadine Witkowski; Peter Balling; Morten Madsen

doi:10.1021/acsaem.9b01454

Sputter-Deposited Titanium Oxide Layers as Efficient Electron Selective Contacts in Organic Photovoltaic Devices

Mina Mirsafaei, Pia Bomholt Jensen, Mehrad Ahmadpour, Harish Lakhotiya, John Lundsgaard Hansen, Brian Julsgaard, Horst Günter Rubahn, Rémi Lazzari, Nadine Witkowski, Peter Balling, Morten Madsen^*

^*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

1 Citation (Scopus)

Abstract

Organic photovoltaics (OPVs) has recently reached power conversion efficiencies of 17.3%, making it a green technology that not only offers short energy payback times and diverse photovoltaic integration schemes, but also can deliver competitive power outputs. OPVs typically employs electron selective contact layers made from low work function n-type metal oxide semiconductors, such as titanium oxide (TiO₂) or zinc oxide (ZnO), developed from a variety of deposition techniques. However, in the case of TiO₂ interlayers, the appearance of unwanted s-shape characteristics has been reported extensively in the literature in the past, for a variety of different deposition methods used. It has been shown that the s-shape arises from negatively charged chemisorbed oxygen, and that it can be deactivated by UV light illumination, which, however, is hardly compatible with real-life OPV application. In this work, we introduce sputtered crystalline titanium oxide layers as efficient s-shape-free electron selective extraction layers in organic solar-cell devices. We demonstrate that the onset of crystallization takes place at substrate growth temperatures of approximately 100 °C for the TiO_x thin films, and that the crystallization onset temperature correlates well with a strong increase in device performance and the removal of any s-shape characteristics. Optical, structural, compositional, and electronic energy-level characterizations of the TiO_x layers are shown in the present work, and point to the formation of an oxide with a low surface-defect density, developed from the sputter-crystallization process. Importantly, well-functioning s-shape-free PTB7:PC₇₀BM devices are demonstrated for TiO_x growth temperatures of 155 °C.

Original language	English
Journal	ACS Applied Energy Materials
Volume	3
Issue	1
Pages (from-to)	253-259
Number of pages	7
ISSN	2574-0962
DOIs	https://doi.org/10.1021/acsaem.9b01454
Publication status	Published - Jan 2020

Keywords

metal oxide interlayers
organic photovoltaics
s-shape-free
sputter deposition
titanium oxide
TRANSPORT LAYER
POLYMER SOLAR-CELLS
FILM
STABILITY
ANATASE

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10.1021/acsaem.9b01454

https://hal.archives-ouvertes.fr/hal-02995171/file/TiO2_OPV_revised_Nov17_AEM%20%281%29.pdf

Cite this

@article{4d77729dbd37443a8dfef0519d7d0458,

title = "Sputter-Deposited Titanium Oxide Layers as Efficient Electron Selective Contacts in Organic Photovoltaic Devices",

abstract = "Organic photovoltaics (OPVs) has recently reached power conversion efficiencies of 17.3%, making it a green technology that not only offers short energy payback times and diverse photovoltaic integration schemes, but also can deliver competitive power outputs. OPVs typically employs electron selective contact layers made from low work function n-type metal oxide semiconductors, such as titanium oxide (TiO2) or zinc oxide (ZnO), developed from a variety of deposition techniques. However, in the case of TiO2 interlayers, the appearance of unwanted s-shape characteristics has been reported extensively in the literature in the past, for a variety of different deposition methods used. It has been shown that the s-shape arises from negatively charged chemisorbed oxygen, and that it can be deactivated by UV light illumination, which, however, is hardly compatible with real-life OPV application. In this work, we introduce sputtered crystalline titanium oxide layers as efficient s-shape-free electron selective extraction layers in organic solar-cell devices. We demonstrate that the onset of crystallization takes place at substrate growth temperatures of approximately 100 °C for the TiOx thin films, and that the crystallization onset temperature correlates well with a strong increase in device performance and the removal of any s-shape characteristics. Optical, structural, compositional, and electronic energy-level characterizations of the TiOx layers are shown in the present work, and point to the formation of an oxide with a low surface-defect density, developed from the sputter-crystallization process. Importantly, well-functioning s-shape-free PTB7:PC70BM devices are demonstrated for TiOx growth temperatures of 155 °C.",

keywords = "metal oxide interlayers, organic photovoltaics, s-shape-free, sputter deposition, titanium oxide, TRANSPORT LAYER, POLYMER SOLAR-CELLS, FILM, STABILITY, ANATASE",

author = "Mina Mirsafaei and Jensen, {Pia Bomholt} and Mehrad Ahmadpour and Harish Lakhotiya and Hansen, {John Lundsgaard} and Brian Julsgaard and Rubahn, {Horst G{\"u}nter} and R{\'e}mi Lazzari and Nadine Witkowski and Peter Balling and Morten Madsen",

year = "2020",

month = jan,

doi = "10.1021/acsaem.9b01454",

language = "English",

volume = "3",

pages = "253--259",

journal = "ACS Applied Energy Materials",

issn = "2574-0962",

publisher = "ACS Publications",

number = "1",

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Sputter-Deposited Titanium Oxide Layers as Efficient Electron Selective Contacts in Organic Photovoltaic Devices. / Mirsafaei, Mina; Jensen, Pia Bomholt; Ahmadpour, Mehrad et al.
In: ACS Applied Energy Materials, Vol. 3, No. 1, 01.2020, p. 253-259.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

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T1 - Sputter-Deposited Titanium Oxide Layers as Efficient Electron Selective Contacts in Organic Photovoltaic Devices

AU - Mirsafaei, Mina

AU - Jensen, Pia Bomholt

AU - Ahmadpour, Mehrad

AU - Lakhotiya, Harish

AU - Hansen, John Lundsgaard

AU - Julsgaard, Brian

AU - Rubahn, Horst Günter

AU - Lazzari, Rémi

AU - Witkowski, Nadine

AU - Balling, Peter

AU - Madsen, Morten

PY - 2020/1

Y1 - 2020/1

N2 - Organic photovoltaics (OPVs) has recently reached power conversion efficiencies of 17.3%, making it a green technology that not only offers short energy payback times and diverse photovoltaic integration schemes, but also can deliver competitive power outputs. OPVs typically employs electron selective contact layers made from low work function n-type metal oxide semiconductors, such as titanium oxide (TiO2) or zinc oxide (ZnO), developed from a variety of deposition techniques. However, in the case of TiO2 interlayers, the appearance of unwanted s-shape characteristics has been reported extensively in the literature in the past, for a variety of different deposition methods used. It has been shown that the s-shape arises from negatively charged chemisorbed oxygen, and that it can be deactivated by UV light illumination, which, however, is hardly compatible with real-life OPV application. In this work, we introduce sputtered crystalline titanium oxide layers as efficient s-shape-free electron selective extraction layers in organic solar-cell devices. We demonstrate that the onset of crystallization takes place at substrate growth temperatures of approximately 100 °C for the TiOx thin films, and that the crystallization onset temperature correlates well with a strong increase in device performance and the removal of any s-shape characteristics. Optical, structural, compositional, and electronic energy-level characterizations of the TiOx layers are shown in the present work, and point to the formation of an oxide with a low surface-defect density, developed from the sputter-crystallization process. Importantly, well-functioning s-shape-free PTB7:PC70BM devices are demonstrated for TiOx growth temperatures of 155 °C.

AB - Organic photovoltaics (OPVs) has recently reached power conversion efficiencies of 17.3%, making it a green technology that not only offers short energy payback times and diverse photovoltaic integration schemes, but also can deliver competitive power outputs. OPVs typically employs electron selective contact layers made from low work function n-type metal oxide semiconductors, such as titanium oxide (TiO2) or zinc oxide (ZnO), developed from a variety of deposition techniques. However, in the case of TiO2 interlayers, the appearance of unwanted s-shape characteristics has been reported extensively in the literature in the past, for a variety of different deposition methods used. It has been shown that the s-shape arises from negatively charged chemisorbed oxygen, and that it can be deactivated by UV light illumination, which, however, is hardly compatible with real-life OPV application. In this work, we introduce sputtered crystalline titanium oxide layers as efficient s-shape-free electron selective extraction layers in organic solar-cell devices. We demonstrate that the onset of crystallization takes place at substrate growth temperatures of approximately 100 °C for the TiOx thin films, and that the crystallization onset temperature correlates well with a strong increase in device performance and the removal of any s-shape characteristics. Optical, structural, compositional, and electronic energy-level characterizations of the TiOx layers are shown in the present work, and point to the formation of an oxide with a low surface-defect density, developed from the sputter-crystallization process. Importantly, well-functioning s-shape-free PTB7:PC70BM devices are demonstrated for TiOx growth temperatures of 155 °C.

KW - metal oxide interlayers

KW - organic photovoltaics

KW - s-shape-free

KW - sputter deposition

KW - titanium oxide

KW - TRANSPORT LAYER

KW - POLYMER SOLAR-CELLS

KW - FILM

KW - STABILITY

KW - ANATASE

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U2 - 10.1021/acsaem.9b01454

DO - 10.1021/acsaem.9b01454

M3 - Journal article

AN - SCOPUS:85077441786

SN - 2574-0962

VL - 3

SP - 253

EP - 259

JO - ACS Applied Energy Materials

JF - ACS Applied Energy Materials

IS - 1

ER -

Sputter-Deposited Titanium Oxide Layers as Efficient Electron Selective Contacts in Organic Photovoltaic Devices

Abstract

Keywords

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