Understanding the role of grain boundaries on charge-carrier and ion transport in Cs2AgBiBr6 thin films
Author(s)
Type
Journal Article
Abstract
Halide double perovskites have gained significant attention, owing to their composition of low-toxicity elements, stability in air, and recent demonstrations of long charge-carrier lifetimes that can exceed 1 s. In particular, Cs2AgBiBr6 has been the subject of many investigations in photovoltaic devices. However, the efficiencies of solar cells based on this double perovskite are still far from the theoretical efficiency limit of the material. Here, we investigate the role of grain size on the optoelectronic properties of Cs2AgBiBr6 thin films. We show through cathodoluminescence measurements that grain boundaries are the dominant non-radiative recombination sites. We also demonstrate through field-effect transistor and temperature-dependent transient current measurements that grain boundaries act as the main channels for ion transport. Interestingly, we find a positive correlation between carrier mobility and temperature, which resembles the hopping mechanism often seen in organic semiconductors. These findings explain the discrepancy between the long diffusion lengths >1 m found in Cs2AgBiBr6 single crystals versus the limited performance achieved in their thin film counterparts. Our work shows that mitigating the impact of grain boundaries will be critical for these double perovskite thin films to reach the performance achievable based on their intrinsic single-crystal properties.
Date Issued
2021-12-02
Date Acceptance
2021-08-16
Citation
Advanced Functional Materials, 2021, 31 (49), pp.1-9
ISSN
1616-301X
Publisher
Wiley
Start Page
1
End Page
9
Journal / Book Title
Advanced Functional Materials
Volume
31
Issue
49
Copyright Statement
© 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Sponsor
Royal Academy of Engineering
Royal Academy Of Engineering
Identifier
https://onlinelibrary.wiley.com/doi/10.1002/adfm.202104981
Grant Number
RF\201718\17101
RF\201718\17101
Subjects
Science & Technology
Physical Sciences
Technology
Chemistry, Multidisciplinary
Chemistry, Physical
Nanoscience & Nanotechnology
Materials Science, Multidisciplinary
Physics, Applied
Physics, Condensed Matter
Chemistry
Science & Technology - Other Topics
Materials Science
Physics
carrier mobilities
grain boundaries
ion migration
lead-free double perovskites
thin film transistors
POLYCRYSTALLINE SOLAR-CELLS
HALIDE DOUBLE PEROVSKITES
EMISSION
PHOTOLUMINESCENCE
MIGRATION
DYNAMICS
02 Physical Sciences
03 Chemical Sciences
09 Engineering
Materials
Publication Status
Published
Date Publish Online
2021-09-04