Bright green emitter of Mn-doped C4H12N2ZnX4 (X = Cl, Br) for X-ray radiography and WLEDs

Zero-dimensional (0D) metal halides based on environmental friendliness, low cost, and earth-abundant elements have gained tremendous attention because of their applications including solid-state lighting, X-ray radiography, anti-counterfeiting labels and beyond. Herein, Mn-doped 0D C4H12N2ZnX4 (X = Cl and Br) with strong green emission has been developed in the application of the scintillator and the white light-emitting diode (WLED). Spectroscopic studies and density functional theory (DFT) calculations clarify the Mn doping effect on the electronic structure of C4H12N2ZnX4. The Mn doping reduces the bandgap owing to the Mn 3d contribution to VBM. The hybrid of Mn 3d orbitals with Br 4p/ Cl 3p enhances the Mn(II) d-d emission resulting in a maximum photoluminescence quantum yield (PLQY) of 99 % in Mn-doped C4H12N2ZnX4. Therefore, the WLED using Mn-doped C4H12N2ZnX4 as a green phosphor shows a high luminous efficacy of 98.52 lm/W and a CRI of 83.3, which is better than other similar WLEDs based on CsPbX3 or Mn-doped Cs2ZnX4. Impressively, Mn-doped C4H12N2ZnX4 ceramic wafer has X-ray radiography with 6–9 LP/mm spatial resolution better than CsI: Tl or MAPbI3.