Vacancy-Ordered Double Perovskite Cs2TeI6 Thin Films for Optoelectronics

Isabel Vázquez-Fernández, Silvia Mariotti, Oliver Hutter, Max Birkett, Tim D. Veal, Theodore D.C. Hobson, Laurie J. Phillips, Lefteris Danos, Pabitra K. Nayak, Henry J. Snaith, Wei Xie, Matthew P. Sherburne, Mark Asta, Ken Durose

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
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Abstract

Alternatives to lead- and tin-based perovskites for photovoltaics and optoelectronics are sought that do not suffer from the disadvantages of toxicity and low device efficiency of present-day materials. Here we report a study of the double perovskite Cs2TeI6, which we have synthesized in the thin film form for the first time. Exhaustive trials concluded that spin coating CsI and TeI4 using an antisolvent method produced uniform films, confirmed as Cs2TeI6 by XRD with Rietveld analysis. They were stable up to 250 °C and had an optical band gap of ∼1.5 eV, absorption coefficients of ∼6 × 104 cm-1, carrier lifetimes of ∼2.6 ns (unpassivated 200 nm film), a work function of 4.95 eV, and a p-type surface conductivity. Vibrational modes probed by Raman and FTIR spectroscopy showed resonances qualitatively consistent with DFT Phonopy-calculated spectra, offering another route for phase confirmation. It was concluded that the material is a candidate for further study as a potential optoelectronic or photovoltaic material.

Original languageEnglish
Pages (from-to)6676-6684
Number of pages9
JournalChemistry of Materials
Volume32
Issue number15
Early online date9 Jul 2020
DOIs
Publication statusPublished - 11 Aug 2020

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