Hybridized C-O-Si Interface States at the Origin of Efficiency Improvement in CNT/Si Solar Cells

Stefano Ponzoni, Simona Achilli, Chiara Pintossi, Giovanni Drera, Luigi Ermenegildo Sangaletti, Paola Castrucci, Maurizio De Crescenzi, Stefania Pagliara

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Despite the astonishing values of the power conversion efficiency reached, in just less than a decade, by the carbon nanotube/silicon (CNT/Si) solar cells, many doubts remain on the underlying transport mechanisms across the CNT/Si heterojunction. Here, by combining transient optical spectroscopy in the femtosecond timescale, X-ray photoemission, and a systematic tracking of I-V curves across all phases of the interlayer SiOx growth at the interface, we grasp the mechanism that adequately preserves charge separation at the junction, hindering the photoexcited carrier recombination. Moreover, supported by ab initio calculations aimed to model the complex CNT-Si heterointerface, we show that oxygen-related states at the interface act as entrapping centers for the photoexcited electrons, thus preventing recombination with holes that can flow from Si to CNT across the SiOx layer.
Original languageEnglish
Pages (from-to)16627-16634
Number of pages8
JournalACS APPLIED MATERIALS & INTERFACES
Volume9
DOIs
Publication statusPublished - 2017

Keywords

  • CNT-Si hybrid junctions
  • J-V characteristics
  • carbon nanotubes
  • interface states
  • photoemission
  • solar cell
  • transient spectroscopy

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