Direct evidence of chemically inhomogeneous, nanostructured, Si-O buried interfaces and their effect on the efficiency of carbon nanotube/Si photovoltaic heterojunctions

Stefania Pagliara, Luigi Ermenegildo Sangaletti, Giovanni Drera, Silvano Del Gobbo, Maurizio Morbidoni, Manuela Scarselli, Maurizio De Crescenzi, Paola Castrucci

Risultato della ricerca: Contributo in rivistaArticolo in rivistapeer review

23 Citazioni (Scopus)

Abstract

An angle resolved X-ray photoemission study of carbon nanotube/silicon hybrid photovoltaic (PV) cells is reported, providing a direct probe of a chemically inhomogeneous, Si-O buried interface between the carbon nanotube (CNT) networked layer and the n-type Si substrate. By changing the photoelectron takeoff angle of the analyzer, a nondestructive in-depth profiling of a CNT/SiOx/SiO2/Si complex interface is achieved. Data are interpreted on the basis of an extensive modeling of the photoemission process from layered structures, which fully accounts for the depth distribution function of the photoemitted electrons. As X-ray photoemission spectroscopy provides direct access to the buried interface, the aging and the effects of chemical etching on the buried interface have been highlighted. This allowed us to show how the thickness and the composition of the buried interface can be related to the efficiency of the PV cell. The results clearly indicate that while SiO2 is related to an increase of the efficiency, acting as a buffer layer, SiOx is detrimental to cell performances, though it can be selectively removed by etching in HF vapors. © 2013 American Chemical Society.
Lingua originaleEnglish
pagine (da-a)18688-18696
Numero di pagine9
RivistaJOURNAL OF PHYSICAL CHEMISTRY. C
Volume117
DOI
Stato di pubblicazionePubblicato - 2013

Keywords

  • carbon nanotubes
  • photoemission
  • photovoltaics
  • solar cells

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