Charge-Carrier Mobility and Localization in Semiconducting Cu₂AgBiI₆ for Photovoltaic Applications

Buizza, Leonardo RV, Wright, Adam D, Longo, Giulia, Sansom, Harry C, Xia, Chelsea Q, Rosseinsky, Matthew J ORCID: 0000-0002-1910-2483, Johnston, Michael B, Snaith, Henry J and Herz, Laura M (2021) Charge-Carrier Mobility and Localization in Semiconducting Cu₂AgBiI₆ for Photovoltaic Applications ACS ENERGY LETTERS, 6 (5). pp. 1729-1739. ISSN 2380-8195, 2380-8195

Text Cu2BiAgI6_Dynamics_Paper_210329.pdf - Author Accepted Manuscript Download (1MB) | Preview

Abstract

Lead-free silver-bismuth semiconductors have become increasingly popular materials for optoelectronic applications, building upon the success of lead halide perovskites. In these materials, charge-lattice couplings fundamentally determine charge transport, critically affecting device performance. In this study, we investigate the optoelectronic properties of the recently discovered lead-free semiconductor Cu2AgBiI6 using temperature-dependent photoluminescence, absorption, and optical-pump terahertz-probe spectroscopy. We report ultrafast charge-carrier localization effects, evident from sharp THz photoconductivity decays occurring within a few picoseconds after excitation and a rise in intensity with decreasing temperature of long-lived, highly Stokes-shifted photoluminescence. We conclude that charge carriers in Cu2AgBiI6 are subject to strong charge-lattice coupling. However, such small polarons still exhibit mobilities in excess of 1 cm2 V-1 s-1 at room temperature because of low energetic barriers to formation and transport. Together with a low exciton binding energy of ∼29 meV and a direct band gap near 2.1 eV, these findings highlight Cu2AgBiI6 as an attractive lead-free material for photovoltaic applications.

Item Type:	Article
Uncontrolled Keywords:	40 Engineering, 3403 Macromolecular and Materials Chemistry, 4016 Materials Engineering, 34 Chemical Sciences
Divisions:	Faculty of Science & Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	09 Aug 2021 08:33
Last Modified:	16 Jun 2026 10:29
DOI:	10.1021/acsenergylett.1c00458
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3132610
Disclaimer:	The University of Liverpool is not responsible for content contained on other websites from links within repository metadata. Please contact us if you notice anything that appears incorrect or inappropriate.