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Published on: October 1, 2019
Giant Exciton Stokes Shift in Interfacially Prepared Cs(Mn/Pb)Cl3 Alloy Nanoplatelets
1Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
Abstract:
Controlling the reabsorption of light by an emitting material is one of the keys to improving the performance of light-emitting devices. We prepare a set of size-dependent Cs(Mn/Pb)Cl3 alloy nanoplatelets (NPls) with substantial enhancement in the exciton Stokes shift, reducing the light-reabsorption significantly. We perform interfacial Mn-alloying using a shuttling ligand that transports MnCl2 from aqueous to nonaqueous phase and delivers it to NPls. While the exciton Stokes shift in 2-5 monolayer (ML) CsPbBr3 NPls rises from 20 to 108 meV, the exciton Stokes shift increases drastically up to 600 meV in 2 ML Cs(Mn/Pb)Cl3 NPls and further reduces upon increasing the thickness. Moreover, the exciton PL peak in the Mn-alloy NPls remains unperturbed by the quantum-confinement effect. A model based on the interplay between Mn2+/Mn3+ during the charge transfer process is proposed, accounting for such a large exciton Stokes shift. Finally, we utilize the large exciton Stokes-shifted alloy NPls for successful demonstration of white-light generation.
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