Photoluminescence Emission Induced by Localized States in Halide Passivated Colloidal Two-Dimensional WS2 Nanoflakes [post]

Rosanna Mastria, Anna Loiudice, Jan Vávra, Concetta Nobile, Riccardo Scarfiello, P. Davide Cozzoli, Nicola Sestu, Daniela Marongiu, Francesco Quochi, Raffaella Buonsanti, Michele Saba, Arrigo Calzolari (+1 others)
2019 unpublished
<p>Engineering physicochemical properties of two-dimensional transition metal dichalcogenide (2D-TMD) materials by surface manipulation is essential for their practical and large-scale application especially for colloidal 2D-TMDs that are plagued by the unintentional formation of structural defects during the synthetic procedure. However, the available methods to manage surface states of 2D-TMDs in solution-phase are still limited hampering the production of high quality colloidal 2D-TMD inks
more » ... oidal 2D-TMD inks to be straightforwardly assembled into actual devices. Here, we demonstrate an efficient solution-phase strategy to passivate surface defect states of colloidally synthetized WS<sub>2 </sub>nanoflakes with halide ligands, resulting in the activation of the photoluminescence emission. Photophysical investigation and density functional theory calculations suggest that halide atoms enable the suppression of non-radiative recombination through the elimination deep gap trap states, and introduce localized states in the energy band structure from which excitons efficiently recombine. Halide passivated WS<sub>2</sub> nanoflakes importantly preserve colloidal stability and photoluminescence emission after several weeks of storing in ambient atmosphere, corroborating the potential of our developed 2D-TMD inks.</p>
doi:10.26434/chemrxiv.8948831 fatcat:jon7v5zjtnbrpgnn2qbuidfsii