In2S3 Atomic Layer Deposition and Its Application as a Sensitizer on TiO2 Nanotube Arrays for Solar Energy Conversion

Shaibal K. Sarkar, Jin Young Kim, David N. Goldstein, Nathan R. Neale, Kai Zhu, C. Michael Elliott, Arthur J. Frank, Steven M. George

Research output: Contribution to journalArticlepeer-review

106 Scopus Citations

Abstract

In2S3 atomic layer deposition (ALD) with indium acetylacetonate (In(acac)3) and H2S was studied with quartz crystal microbalance (QCM), X-ray reflectivity (XRR), and Fourier transform infrared (FTIR) spectroscopy techniques. Subsequent In 2S3 ALD on TiO2 nanotube arrays defined a model semiconductor sensitized solar cell. For In2S3 ALD on initial Al2O3 ALD surfaces, the In2S 3 ALD displayed a nucleation period of ∼60-70 cycles followed by a linear growth region. These results were obtained under ALD conditions that were not completely self-limiting for the In(acac)3 exposure because of the low In(acac)3 vapor pressure. The growth per cycle decreased at higher temperature over the temperature range from 130 to 170 °C at these same reactant conditions. The growth per cycle was 0.30-0.35 A per cycle at 150 °C as determined by QCM and XRR measurements at higher In(acac)3 exposures where the surface reactions were self-limiting chemistry versus In(acac)3 and H2S exposures. The FTIR examinations revealed that the nucleation period on Al2O3 ALD surfaces may be related to the formation of Al(acac)* species that act to poison the initial Al2O3 ALD surface. X-ray diffraction investigations revealed β-In2S3 ALD films and X-ray photoelectron measurements were consistent with In2S3 films. The In2S3 ALD was employed as a semiconductor sensitizer on TiO2 nanotube arrays for solar conversion. Scanning electron microscopy and energy dispersive X-ray analysis imaging revealed In2S3 over the full length of the TiO2 nanotube array after 175 cycles of In2S3 ALD at 150 °C at reactant exposure conditions that were self-limiting on flat substrates. The photoelectrochemical properties of these In2S3 ALD-sensitized TiO2 nanotube arrays with a Co2+/Co 3+ electrolyte were then characterized by measuring the photocurrent density versus voltage and the external quantum efficiency versus photon energy. A small quantum efficiency of ∼10% was observed that can be attributed to charge recombination losses and charge injection/collection processes.

Original languageAmerican English
Pages (from-to)8032-8039
Number of pages8
JournalJournal of Physical Chemistry C
Volume114
Issue number17
DOIs
StatePublished - 2010

NREL Publication Number

  • NREL/JA-590-48501

Keywords

  • atomic layer deposition
  • quantum efficiencey
  • X-ray reflectivity
  • XRR

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