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Composition Dictates Octahedral Tilt and Photostability in Halide Perovskites.

Published version
Peer-reviewed

Repository DOI


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Abstract

Halide perovskites are excellent candidate materials for use in solar cell, LED, and detector devices, in part because their composition can be tuned to achieve ideal optoelectronic properties. Empirical efficiency optimization has led the field toward compositions rich in FA (formamidinium) on the A-site and I on the X-site, with additional small amounts of MA (methylammonium) or Cs A-site cations and Br X-site anions. However, it is not clear how and why the specific compositions of alloyed, that is, mixed component, halide perovskites relate to photo-stability of the materials. Here, this work combines synchrotron grazing incidence wide-angle X-ray scattering, photoluminescence, high-resolution scanning electron diffraction measurements and theoretical modelling to reveal the links between material structure and photostability. Namely, this work finds that increased octahedral titling leads to improved photo-stability that is correlated with lower densities of performance-harming hexagonal polytype impurities. These results uncover the structural signatures underpinning photo-stability and can therefore be used to make targeted changes to halide perovskites, bettering the commercial prospects of technologies based on these materials.

Description

Publication status: Published


Funder: Gonville and Caius College, Cambridge


Funder: Cambridge Philosophical Society; doi: http://dx.doi.org/10.13039/100013858


Funder: British Spanish Society


Funder: Sir Richard Stapley Educational Trust; doi: http://dx.doi.org/10.13039/501100016406


Funder: Rank Prize Fund


Funder: Ernest Oppenheimer Fund


Funder: Schmidt Science Fellowships


Funder: Taiwan Cambridge Scholarship


Funder: D.M.P. Foundation


Funder: St John's College, Cambridge


Funder: Royal Academy of Engineering; doi: http://dx.doi.org/10.13039/501100000287


Funder: Diamond Light Source; doi: http://dx.doi.org/10.13039/100011889

Keywords

X‐ray diffraction, density functional theory, electron microscopy, perovskite, photovoltaics

Journal Title

Adv Mater

Conference Name

Journal ISSN

0935-9648
1521-4095

Volume Title

Publisher

Wiley
Sponsorship
Engineering and Physical Sciences Research Council (EP/L015978/1)
European Research Council (756962)
Engineering and Physical Sciences Research Council (EP/R023980/1)
Engineering and Physical Sciences Research Council (EP/S030638/1)
EPSRC (EP/V012932/1)