Investigation of the electric field in TiO2/FTO junctions used in dye-sensitized solar cells by photocurrent transients.

The journal of physical chemistry. B · 2005 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 3569

Study snapshot

PublicationThe journal of physical chemistry. B · 2005

Study typeother

Reported directionUnclear

Evidence ratingInsufficient

Abstract

We have investigated the electrostatic potential distribution in compact and nanoporous TiO2 films, deposited on conducting F-doped SnO2 substrate (FTO), which are used in dye-sensitized solar cells. The TiO2 films were immersed into aqueous electrolyte and excited from the FTO side by light pulses of a N2 laser while the current response was measured as a function of time. The measurements were carried out as a function of the pH value of the electrolyte and at different electrostatic potentials. For compact TiO2 films, the sign of the transient current at short response times changed when the applied electrostatic potential or the pH value was decreased. This was not observed for mesoporous TiO2 films directly deposited onto the FTO substrate without a compact TiO2 layer. We interpret the results in terms of a macroscopic electric field across the compact layer which is changed by the applied potential or the pH of the electrolyte. In contrast, measurements on mesoporous TiO2 films indicate that the contact region is mainly field-free, and we explain our results by a very sharp electrostatic potential drop within the first layer of particles at the TiO2/FTO interface.

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Study typeother

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

Photocurrent transients in compact TiO2 films on FTO showed a change in the sign of the short-time transient current when the applied electrostatic potential or electrolyte pH was decreased. This sign change was not observed for mesoporous TiO2 films deposited directly on FTO without a compact layer. The authors interpret the compact-layer behavior as evidence of a macroscopic electric field across the compact layer modulated by applied potential or pH, whereas mesoporous films suggest a mainly field-free contact region with a sharp potential drop within the first particle layer at the TiO2/FTO interface.

Outcomes measured

electrostatic potential distribution in TiO2 films on FTO
photocurrent transient response as a function of time
effect of electrolyte pH and applied electrostatic potential on transient current sign
inference about macroscopic electric field across compact TiO2 layer vs field-free contact region in mesoporous films

View raw extracted JSON

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  "study_type": "other",
  "exposure": {
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    "source": null,
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    "duration": null
  },
  "population": null,
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  "outcomes": [
    "electrostatic potential distribution in TiO2 films on FTO",
    "photocurrent transient response as a function of time",
    "effect of electrolyte pH and applied electrostatic potential on transient current sign",
    "inference about macroscopic electric field across compact TiO2 layer vs field-free contact region in mesoporous films"
  ],
  "main_findings": "Photocurrent transients in compact TiO2 films on FTO showed a change in the sign of the short-time transient current when the applied electrostatic potential or electrolyte pH was decreased. This sign change was not observed for mesoporous TiO2 films deposited directly on FTO without a compact layer. The authors interpret the compact-layer behavior as evidence of a macroscopic electric field across the compact layer modulated by applied potential or pH, whereas mesoporous films suggest a mainly field-free contact region with a sharp potential drop within the first particle layer at the TiO2/FTO interface.",
  "effect_direction": "unclear",
  "limitations": [],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "TiO2",
    "FTO",
    "dye-sensitized solar cells",
    "photocurrent transients",
    "electrostatic potential distribution",
    "pH",
    "applied potential",
    "compact film",
    "mesoporous film",
    "electric field"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1021/jp046211y
PubMed: 16852145

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