Wavelength-Dependent Charge Carrier Dynamics for Single Pixel Color Sensing Using Graded Perovskite Structures

N. Ganesh, Ravichandran Shivanna, Richard H. Friend, K. S. Narayan

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

We report smart color-sensing devices of two-dimensional lead halide perovskites that exhibit a graded band gap across the film. We observe that the device short-circuit photocurrent is strongly dependent on excitation wavelength λ, and this arises through photoabsorption at different depths in the sample due to the graded bandgaps present. This λ signature in the response of the device is observed in case of steady-state excitation when incident from the high bandgap side of the film, where a complete reversal in the polarity of the photocurrent Iph(t) is obtained as the excitation wavelength is spanned across the visible spectrum. The transient photocurrent reveals λ-specific response arrived from a combination of positive and negative Iph(t) components. The uniqueness of Iph(t) as a function of incident λ can be utilized to examine spectral purity without dispersive optical elements. An equivalent circuit model description provides a possible glimpse into the physical sources involved in contributing to these features.

Original languageEnglish
Pages (from-to)6577-6584
Number of pages8
JournalNano Letters
Volume19
Issue number9
DOIs
StatePublished - Sep 11 2019
Externally publishedYes

Funding

All authors acknowledge support from EPSRC project ‘Strategic University Network to Revolutionize Indian Solar Energy-SUNRISE (EP/P032591/1)’. R.S. acknowledges the Royal Society Newton-Bhabha International Fellowship.

Keywords

  • Graded bandgap hybrid organic-inorganic perovskite
  • off-cycle response
  • optical time division multiplexing
  • transient photocurrent

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