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New publication of CIEL team : Blue Emission From Charge Transfer Excitons in Hybrid Organic-Inorganic Quantum Wires: (ABT) [PbCl3]”

O. Medhioub, H. Barkaoui, A. Samet, S. Pillet, S. Triki, Y. Abid

J. Phys. Chem. C 2019, 123, 43, 26547-26553

Organic-inorganic Hybrid (OIH) materials have the potential of providing synergetic properties and promising novel optical properties. This work focuses on the charge transfer (CT) excitons which play a critical role in a new OIH material, with formula (C7H7N2S) [PbCl3] abbreviated as ABTPbCl3. Its crystal structure is built up from [Pb2Cl8]4- clusters, forming 1D infinite double chains surrounded by 2-aminobenzothiazole (ABT) organic molecules. The density of states calculations demonstrates that ABTPbCl3 has a type-II band alignment, where the Valence Band (VB) and Conduction Band (CB) of the inorganic wires lie upon those of the organic component, respectively. Under UV excitation, the photoluminescence (PL) spectrum of ABTPbCl3 shows a band emission centered at 483 nm. Based on the band alignment, we attribute this bluish emission to CT excitons, which have a lifetime of 3.19 ns. The carriers dynamics is investigated by measuring the luminescence spectra as a function of temperature. At temperature below 210 K, the recombination of carriers is dominated by delocalized excitons, while the mixture of delocalized excitons, electrons and holes are dominating at higher temperature.