期刊
ADVANCED FUNCTIONAL MATERIALS
卷 32, 期 6, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.202108392
关键词
charge-carrier localization; perovskites; polarons; silver-bismuth-halides; spectroscopy
类别
资金
- Engineering and Physical Sciences Research Council (EPSRC)
- EPSRC Centre for Doctoral Training in New and Sustainable Photovoltaics
- Oxford-Radcliffe Scholarship
- TUM-IAS
- EPSRC Prosperity Partnership [EP/S004947/1]
- EPSRC Centre for Doctoral Training in Plastic Electronics
- Engineering and Physical Sciences Research Council [EP/S004947/1] Funding Source: researchfish
The study demonstrates that silver-bismuth based semiconductors exhibit good semiconductor properties, with optoelectronic properties significantly improved with increasing copper content. The presence of Cu+ enhances charge-carrier transport in the materials and reduces exciton binding energies.
Silver-bismuth based semiconductors represent a promising new class of materials for optoelectronic applications because of their high stability, all-inorganic composition, and advantageous optoelectronic properties. In this study, charge-carrier dynamics and transport properties are investigated across five compositions along the AgBiI4-CuI solid solution line (stoichiometry Cu-4x(AgBi)(1-x)I-4). The presence of a close-packed iodide sublattice is found to provide a good backbone for general semiconducting properties across all of these materials, whose optoelectronic properties are found to improve markedly with increasing copper content, which enhances photoluminescence intensity and charge-carrier transport. Photoluminescence and photoexcitation-energy-dependent terahertz photoconductivity measurements reveal that this enhanced charge-carrier transport derives from reduced cation disorder and improved electronic connectivity owing to the presence of Cu+. Further, increased Cu+ content enhances the band curvature around the valence band maximum, resulting in lower charge-carrier effective masses, reduced exciton binding energies, and higher mobilities. Finally, ultrafast charge-carrier localization is observed upon pulsed photoexcitation across all compositions investigated, lowering the charge-carrier mobility and leading to Langevin-like bimolecular recombination. This process is concluded to be intrinsically linked to the presence of silver and bismuth, and strategies to tailor or mitigate the effect are proposed and discussed.
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