Optical and photoelectrical properties of low-concentration-Mn-doped CsPbBr₃ nanocrystals

Abstract

Doping of Cesium Lead Bromide (CsPbBr3) perovskite nanocrystals offers the effective control on the optical and optoelectrical properties leading to possibilities for several new applications. Herein, CsPbBr3 perovskite nanocrystals are synthesised with low concentration of Manganese (Mn) doping into perovskite lattice using Manganese chloride (MnCl2) precursor. A shift in x-ray diffraction peaks towards higher angles indicates that Mn as a dopant is present inside CsPbBr3 lattice. The change in the MnCl2 precursor concentration from 5 to 10 mmol, results an increment in the atomic percentage (At.%) of Mn from 0.3 to 0.5% into the CsPbBr3 crystal. Low concentration of Mn doping (0.3 At.%) in CsPbBr3 results in enhancement of green emission, while higher Mn doping (0.5 At.%) results in blue emission. The band gap of CsPbBr3 nanocrystals increases from 2.31 eV to 2.53 eV with increase in the concentration of manganese. The dark and photoelectrical conductivity of CsPbBr3 nanocrystals is improved in case of low concentration (0.3 At.%) of Mn doping. The ratio of photocurrent vs. dark current is found to be ∼182 in Mn doped CsPbBr3 crystals film as compared to ∼101 for undoped CsPbBr3 crystals film. The low concentration of Mn doping improves the overall electrical and photoelectrical conductivity of CsPbBr3 perovskite nanocrystals.