Evolving Stark Effect During Growth of Perovskite Nanocrystals Measured Using Transient Absorption
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Date
2020-10
Authors
Sadighian, James C.
Wilson, Kelly S.
Crawford, Michael L.
Wong, Cathy Y.
Journal Title
Journal ISSN
Volume Title
Publisher
Frontiers
Abstract
Methylammonium lead triiodide (MAPbI3) nanocrystals (NCs) are emerging materials for
a range of optoelectronic applications. Photophysical characterization is typically limited
to structurally stable NCs owing to the long timescales required for many spectroscopies,
preventing the accurate measurement of NCs during growth. This is a particular challenge
for non-linear spectroscopies such as transient absorption. Here we report on the use
of a novel single-shot transient absorption (SSTA) spectrometer to study MAPbI3 NCs
as they grow. Comparing the transient spectra to derivatives of the linear absorbance
reveals that photogenerated charge carriers become localized at surface trap states
during NC growth, inducing a TA lineshape characteristic of the Stark effect. Observation
of this Stark signal shows that the contribution of trapped carriers to the TA signal
declines as growth continues, supporting a growth mechanism with increased surface
ligation toward the end of NC growth. This work opens the door to the application of
time-resolved spectroscopies to NCs in situ, during their synthesis, to provide greater
insight into their growth mechanisms and the evolution of their photophysical properties.
Description
8 pages
Keywords
perovskite, nanocrystals, surface, ultrafast, spectroscopy, Stark effect, transient absorption
Citation
Sadighian JC, Wilson KS, Crawford ML and Wong CY (2020) Evolving Stark Effect During Growth of Perovskite Nanocrystals Measured Using Transient Absorption. Front. Chem. 8:585853. doi: 10.3389/fchem.2020.585853