Levine, I;
Shimizu, K;
Lomuscio, A;
Kulbak, M;
Rehermann, C;
Zohar, A;
Abdi-Jalebi, M;
... Cahen, D; + view all
(2021)
Direct Probing of Gap States and Their Passivation in Halide Perovskites by High-Sensitivity, Variable Energy Ultraviolet Photoelectron Spectroscopy.
The Journal of Physical Chemistry C
, 125
(9)
pp. 5217-5225.
10.1021/acs.jpcc.0c11627.
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Abstract
Direct detection of intrinsic defects in halide perovskites (HaPs) by standard methods utilizing optical excitation is quite challenging, due to the low density of defects in most samples of this family of materials (≤10^{15} cm^{–3} in polycrystalline thin films and ≤10^{11} cm^{–3} in single crystals, except melt-grown ones). While several electrical methods can detect defect densities <10^{15} cm^{–3}, such as deep level transient spectroscopy (DLTS) or thermally stimulated current (TSC), they require preparation of ohmic and/or rectifying electrical contacts to the sample, which not only poses a challenge by itself in the case of HaPs but also may create defects at the contact–HaP interface and introduce extrinsic defects into the HaP. Here, we show that low-energy photoelectron spectroscopy measurements can be used to obtain directly the energy position of gap states in Br-based wide-bandgap (E_{g} > 2 eV) HaPs. By measuring HaP layers on both hole- and electron-contact layers, as well as single crystals without contacts, we conclude that the observed deep defects are intrinsic to the Br-based HaP, and we propose a passivation route via the incorporation of a 2D-forming ligand into the precursor solution.
| Type: | Article |
|---|---|
| Title: | Direct Probing of Gap States and Their Passivation in Halide Perovskites by High-Sensitivity, Variable Energy Ultraviolet Photoelectron Spectroscopy |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/acs.jpcc.0c11627 |
| Publisher version: | https://doi.org/10.1021/acs.jpcc.0c11627 |
| Additional information: | © 2021 The Authors. Published by American Chemical Society under the terms of the Creative Commons Attribution 4.0 license (https://creativecommons.org/licenses/by-nc/4.0/). |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > MAPS Faculty Office UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > MAPS Faculty Office > Institute for Materials Discovery |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10123439 |
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