Strong room-temperature blue-violet photoluminescence of multiferroic BaMnF$_4$

TL;DR

This study reports strong room-temperature blue-violet photoluminescence in BaMnF₄ microsheets, with insights into the electronic transitions responsible for the emission, highlighting potential for tunable photon generation in ferroelectric materials.

Contribution

The paper demonstrates high-yield room-temperature photoluminescence in BaMnF₄ and elucidates its electronic transition mechanisms through first-principles calculations, revealing new pathways for tunable photonic applications.

Findings

Photoluminescence quantum yield of 67% at room temperature.

Identification of two emission peaks at 385 nm and 410 nm.

Observation of photon self-absorption causing intensity drop at 400 nm.

Abstract

BaMnF$_4$ microsheets have been prepared by hydrothermal method. Strong room-temperature blue-violet photoluminescence has been observed (absolute luminescence quantum yield 67%), with two peaks located at 385 nm and 410 nm, respectively. More interestingly, photon self-absorption phenomenon has been observed, leading to unusual abrupt drop of luminescence intensity at wavelength of 400 nm. To understand the underlying mechanism of such emitting, the electronic structure of BaMnF$_4$ has been studied by first principles calculations. The observed two peaks are attributed to electrons' transitions between the upper-Hubbard bands of Mn's $t_{2g}$ orbitals and the lower-Hubbard bands of Mn's $e_g$ orbitals. Those Mott gap mediated d-d orbital transitions may provide additional degrees of freedom to tune the photon generation and absorption in ferroelectrics.