Mn:CsPbBr₃ Nanoplatelets for Bright White-Emitting Displays

Abstract

Controlled ion-exchange reactions endow CsPbX3 nanocrystals (NCs) with superior photoluminescence (PL) properties. In this study, MnX2 (X = Cl and Br) was used as the precursor of Mn for cation-exchange reactions to synthesize Mn-doped CsPbBr3 nanoplatelets (NPLs). The anion-derived cation-exchange reactions occur within a short period of time. The PL peaks of CsPbBr3 NPLs were adjusted from 460 to 500 nm (redshift) by controlling the thickness of NPLs. The ion-exchange process of MnBr2 and CsPbBr3 NPLs resulted in Mn doping because of the PL peak (∼610 nm) of Mn ions observed. With increasing MnBr2 incorporation, CsPbBr3 NPLs excited d-d transfer from Mn ions, resulting in an increased PL intensity of Mn ions. Two PL peaks from CsPbBr3 NPLs and Mn ions were obtained, in which the PL color of Mn:CsPbBr3 composites changed from blue to white. The PL quantum yield (PLQYs) of Mn:CsPbBr3 composites is up to 64.4%. Br ion-derived ion exchange plays an important role for Mn ions that enter the crystal lattices instead of Pb NPLs. After ion exchange, the morphology of the sample remained unchanged. However, the PLQYs of the sample increased. The average lifetimes of the sample depended strongly on the emission wavelength. With the increasing amount of Mn doping, the lifetime was increased to 1.63 ms (λem = 610 nm) from the ns level. A white-emitting sample with the Commission Internationale de I′Eclairage (CIE) coordinates of 0.3013 and 0.3089, as well as PLQYs of 95% were obtained by adding green-emitting CsPbBr3 nanocrystals in Mn:CsPbBr3 NPLs, suggesting an important application in displaying devices.