Mir, Wasim J. and Warankar, Avinash and Acharya, Ashutosh and Das, Shyamashis and Mandal, Pankaj and Nag, Angshuman (2017) Colloidal thallium halide nanocrystals with reasonable luminescence, carrier mobility and diffusion length. In: Chemical Science, 8 (6). pp. 4602-4611. ISSN 2041-6520
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Abstract
Colloidal lead halide based perovskite nanocrystals (NCs) have been recently established as an interesting class of defect-tolerant NCs with potential for superior optoelectronic applications. The electronic band structure of thallium halides (TlX, where X = Br and I) show a strong resemblance to lead halide perovskites, where both Pb2+ and Tl+ exhibit a 6s2 inert pair of electrons and strong spin-orbit coupling. Although the crystal structure of TlX is not perovskite, the similarities of its electronic structure with lead halide perovskites motivated us to prepare colloidal TlX NCs. These TlX NCs exhibit a wide bandgap (>2.5 eV or <500 nm) and the potential to exhibit a reduced density of deep defect states. Optical pump terahertz (THz) probe spectroscopy with excitation fluence in the range of 0.85-5.86 × 1013 photons per cm2 on NC films shows that the TlBr NCs possess high effective carrier mobility (∼220 to 329 cm2 V-1 s-1), long diffusion length (∼0.77 to 0.98 μm), and reasonably high photoluminescence efficiency (∼10%). This combination of properties is remarkable compared to other wide-bandgap (>2.5 eV) semiconductor NCs, which suggests a reduction in the deep-defect states in the TlX NCs. Furthermore, the ultrafast carrier dynamics and temperature-dependent reversible structural phase transition together with its influence on the optical properties of the TlX NCs are studied.
| Item Type: | Journal Article |
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| Publication: | Chemical Science |
| Publisher: | Royal Society of Chemistry |
| Additional Information: | The Copyright of this article belongs to the authors. |
| Keywords: | Carrier mobility; Defect density; Defects; Electronic structure; Energy gap; Lead; Light; Magnetooptical effects; Nanocrystals; Optical properties; Optical pumping; Perovskite; Terahertz spectroscopy; Thallium; Wide band gap semiconductors; Effective carrier mobility; Electronic band structure; Optoelectronic applications; Photoluminescence efficiency; Spin-orbit couplings; Structural phase transition; Temperature dependent; Ultrafast carrier dynamics; Crystal structure |
| Department/Centre: | Division of Chemical Sciences > Solid State & Structural Chemistry Unit |
| Date Deposited: | 01 Jun 2022 05:38 |
| Last Modified: | 01 Jun 2022 05:38 |
| URI: | https://eprints.iisc.ac.in/id/eprint/72985 |
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