A-Site FA⁺ Doping-Enhanced Photoluminescence Efficiency and Photostability of Mn-Doped Perovskite Nanocrystals

Abstract

Improving the optical and structural stability of highly luminescent Mn2+-doped CsPbCl3–yBry (Mn:CsPbCl3–yBry) nanocrystals (NCs) under ultraviolet illumination is very necessary for their application in solid-state lighting. Herein, greatly improved photoluminescence (PL) quantum yield (QY) and illumination stability were observed in Mn:CsPbCl3 NCs by incorporation of an appropriate FA+ amount into the crystal lattice. The Mn:FAxCs1–xPbCl3 NCs showed higher PL QYs (up to 76%), longer Mn2+ PL lifetimes, and nearly single-exponential decay relative to the Mn:CsPbCl3 ones. With the increase in irradiation time, a slowly reduced PL intensity and an almost unchanged PL peak position and linewidth of Mn2+ ions in Mn:FA0.15Cs0.85PbCl3 NCs were found, suggesting that the mixing of FA+ and Cs+ can increase the tolerance of the lattice and improve the photostability of the NCs. Under high-power ultraviolet irradiation, the light-induced Mn2+ PL attenuation of Mn:FA0.15Cs0.85PbCl3 NCs was slower than that of the ones without FA+, and no divisive emission peaks representing Br-rich and Cl-rich regions appeared in Mn:FA0.15Cs0.85PbCl3–yBry NCs, which was consistent with the result that the X-ray diffraction peaks of the NCs with FA+ remained constant with irradiation time. This indicates that severe Mn2+ ion diffusion and halogen ion segregation can be effectively inhibited by adding FA+ into the Mn-doped perovskite NCs.