Pure Tunable Emissions from Cesium Manganese Bromide by Monitoring the Crystal Fields Through a Sustainable Approach

Abstract Research on manganese (Mn) halide perovskite derivatives with tunable emissions and high color purity have gathered a significant amount of attention for display technology. Despite of mesmerizing optical properties, the synthesis of these all‐inorganic Mn halide compounds is followed by complex and toxic processes. Second, a precise control over the synthesis parameters is mandatory to achieve their pure emissions. Therefore, an ecologically sustainable water‐based solution approach is adapted here to tailor the phases and emissions of cesium manganese bromide (Cs‐Mn‐Br) perovskite derivatives. It is observed that a controlled injection of solution stabilizer plays a pivotal role in engineering the intrinsic properties of Mn halide perovskites. This solution stabilizer interacts with the Mn‐ions of those perovskite derivatives influencing their surrounding coordination environment and pure emission from then. A pure green emission with PLQY of 82% is achieved from as prepared Cs₃MnBr₅, whereas CsMnBr₃ showed a red emission with PLQY of ≈20%. Encouraged by these properties phosphor‐driven light emitting diodes (LED) are designed that show a steady electroluminescence intensity. The CIE coordinates of the Cs₃MnBr₅ and CsMnBr₃ LED prototypes are at (0.224, 0.659) and (0.688, 0.316). This study showcases simple, eco‐friendly tactics for developing green and red LED prototypes contributing toward sustainable device design.