Self-Assembled Vertically Aligned Hetero-Epitaxial ZnO/CdS Core/Shell Array by all CBD Process: Platform for Enhanced Visible-Light-Driven PEC Performance

Rekha Bai, Dinesh Kumar, Sujeet Chaudhary, Dinesh K. Pandya

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

We report on an all chemical bath deposition (CBD) fabrication of self-assembled vertically aligned heteroepitaxy grown (002)ZnO//(002)CdS ZnO/CdS core/shell nanorod (NR) arrays. These single-technique processed NR arrays comprising of CdS QDs conformally and epitaxially grown on faceted single-crystalline ZnO NRs achieve effective charge separation and collection, resulting from visible light driven highest ever, reported photocurrent density without any postdeposition process step, unlike previous such studies. The low ion-flux controlled ion-by-ion deposition induces chemical-epitaxy growth mechanism, with a 38° tilt of CdS c-axis. Structural characterizations confirm the homogeneous growth of (002) CdS QDs (size ∼30 nm) on hexagonal prismaticc-axis oriented ZnO NRs (400 nm diameter). Compared with pristine ZnO NR array, a 20-fold enhancement in photocurrent density (∼8.5 mA/cm2 at +1.0 V vs Ag/AgCl) under AM1.5 light illumination is observed without any additional passivation/sensitization layer, attributed to the enlarged defect-free sharp ZnO/CdS interface and improved optical properties involving high visible light absorption as well as suppressed recombination of photoinduced charge carriers due to staircase type-II band alignment and hence effective charge separation and transport. Low-temperature short-time anneal further enhances the photocurrent density to 9-10 mA/cm2 and photoconversion efficiency to 4.4%. Our results demonstrate that formation of atomically aligned interface is key to realizing high performance junction without any postdeposition step and have significant bearing on photoelectrochemical as well as photovoltaic performance of ZnO/CdS radial junction devices.

Original languageEnglish
Pages (from-to)14408-14419
Number of pages12
JournalJournal of Physical Chemistry C
Volume122
Issue number26
DOIs
StatePublished - 5 Jul 2018
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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