Skip to main content
Home
Department Of Physics text logo
  • Research
    • Our research
    • Our research groups
    • Our research in action
    • Research funding support
    • Summer internships for undergraduates
  • Study
    • Undergraduates
    • Postgraduates
  • Engage
    • For alumni
    • For business
    • For schools
    • For the public
Menu
Representation of THz spectroscopy of a metamaterial with a Nanowire THz sensor

Representation of THz spectroscopy of a metamaterial with a Nanowire THz sensor

Credit: Rendering by Dimitars Jevtics

Prof Michael Johnston

Professor of Physics

Research theme

  • Photovoltaics and nanoscience

Sub department

  • Condensed Matter Physics

Research groups

  • Terahertz photonics
  • Advanced Device Concepts for Next-Generation Photovoltaics
michael.johnston@physics.ox.ac.uk
Johnston Group Website
  • About
  • Publications

Electronic traps and phase segregation in lead mixed-halide Perovskite

ACS Energy Letters American Chemical Society 4:1 (2018) 75-84

Authors:

Alexander J Knight, Adam D Wright, Jay B Patel, David P McMeekin, Henry J Snaith, Michael B Johnston, Laura M Herz

Abstract:

An understanding of the factors driving halide segregation in lead mixed-halide perovskites is required for their implementation in tandem solar cells with existing silicon technology. Here we report that the halide segregation dynamics observed in the photoluminescence from CH3NH3Pb(Br0.5I0.5)3 is strongly influenced by the atmospheric environment, and that encapsulation of films with a layer of poly(methyl methacrylate) allows for halide segregation dynamics to be fully reversible and repeatable. We further establish an empirical model directly linking the amount of halide segregation observed in the photoluminescence to the fraction of charge carriers recombining through trap-mediated channels, and the photon flux absorbed. From such quantitative analysis we show that under pulsed illumination, the frequency of the modulation alone has no influence on the segregation dynamics. Additionally, we extrapolate that working CH3NH3Pb(Br0.5I0.5)3 perovskite cells would require a reduction of the trap-related charge carrier recombination rate to ≲105s–1 in order for halide segregation to be sufficiently suppressed.
More details from the publisher
Details from ORA
More details

Publisher Correction: High irradiance performance of metal halide perovskites for concentrator photovoltaics

Nature Energy Springer Nature America, Inc (2018)

Authors:

Z Wang, Q Lin, B Wenger, Mark Christoforo, Y-H Lin, MT Klug, MICHAEL Johnston, LAURA Herz, HJ Snaith

Abstract:

© 2018, Springer Nature Limited. When this Article was originally published, an old version of the associated Supplementary Information file was uploaded. This has now been replaced.
More details from the publisher
More details
More details

Raman Spectrum of the Organic-Inorganic Halide Perovskite CH3NH3PbI3 from First Principles and High-Resolution Low-Temperature Raman Measurements

JOURNAL OF PHYSICAL CHEMISTRY C 122:38 (2018) 21703-21717

Authors:

Miguel A Perez-Osorio, Qianqian Lin, Richard T Phillips, Rebecca L Milot, Laura M Herz, Michael B Johnston, Feliciano Giustino
More details from the publisher
Details from ORA
More details
More details

Engineering semiconductor nanowires for photodetection: from visible to terahertz

SPIE, the international society for optics and photonics 10729 (2018) 1072909

Authors:

Hannah J Joyce, Jack Alexander-Webber, Kun Peng, Michael B Johnston, Patrick Parkinson, H Hoe Tan, C Jagadish
More details from the publisher

The effects of doping density and temperature on the optoelectronic properties of formamidinium tin triiodide thin films

Advanced Materials Wiley 30:44 (2018) 1804506

Authors:

Rebecca L Milot, Matthew T Klug, Christopher Davies, Zhiping Wang, Hans AP Kraus, Henry J Snaith, Michael B Johnston, Laura M Herz

Abstract:

Intrinsic and extrinsic optoelectronic properties are unraveled for formamidinium tin triiodide (FASnI3) thin films, whose background hole doping density was varied through SnF2 addition during film fabrication. Monomolecular charge-carrier recombination exhibits both a dopant-mediated part that grows linearly with hole doping density and remnant contributions that remain under tin-enriched processing conditions. At hole densities near 1020 cm-3, a strong Burstein-Moss effect increases absorption onset energies by ~300meV beyond the band gap energy of undoped FASnI3 (shown to be 1.2 eV at 5 K and 1.35 eV at room temperature). At very high doping densities (1020 cm-3), temperature-dependent measurements indicate that the effective charge-carrier mobility is suppressed through scattering with ionized dopants. Once the background hole concentration is nearer 1019 cm-3 and below, the charge-carrier mobility increases with decreasing temperature according to ~T-1.2, suggesting it is limited mostly by intrinsic interactions with lattice vibrations. For the lowest doping concentration of 7.2´1018 cm^-3, charge-carrier mobilities reach a value of 67 cm2V-1s-1at room temperature and 470 cm2V-1s-1 at 50 K. Intra-excitonic transitions observed in the THz-frequency photoconductivity spectra at 5K reveal an exciton binding energy of only 3.1 meV for FASnI3, in agreement with the low bandgap energy exhibited by this perovskite.
More details from the publisher
Details from ORA
More details
More details

Pagination

  • First page First
  • Previous page Prev
  • …
  • Page 23
  • Page 24
  • Page 25
  • Page 26
  • Current page 27
  • Page 28
  • Page 29
  • Page 30
  • Page 31
  • …
  • Next page Next
  • Last page Last

Footer Menu

  • Contact us
  • Giving to the Dept of Physics
  • Work with us
  • Media

User account menu

  • Log in

Follow us

FIND US

Clarendon Laboratory,

Parks Road,

Oxford,

OX1 3PU

CONTACT US

Tel: +44(0)1865272200

University of Oxfrod logo Department Of Physics text logo
IOP Juno Champion logo Athena Swan Silver Award logo

© University of Oxford - Department of Physics

Cookies | Privacy policy | Accessibility statement

Built by: Versantus

  • Home
  • Research
  • Study
  • Engage
  • Our people
  • News & Comment
  • Events
  • Our facilities & services
  • About us
  • Current students
  • Staff intranet