Synergistic effects in Mn2O3/CuO nanocomposites for enhanced and color-tunable emission for optoelectronic applications

Abstract This work demonstrates the simple, economical, and rapid synthesis of magnesia oxide (Mn 2 O 3 ), copper oxide (CuO), and their compound Mn 2 O 3 /CuO composite, employing fundamental green practices. The as-synthesized Mn 2 O 3 , CuO, and Mn 2 O 3 /CuO have been evaluated using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and field-emission scanning electron microscopy (FESEM). The presence of distinct Mn 2 O 3 and CuO phases, as well as the interphase between them, is evident in the TEM micrographs. Using the Tauc plot from absorption spectra, the energy bandgaps of pure Mn 2 O 3 , CuO, and the Mn 2 O 3 /CuO composite were estimated to be 2.6, 2.1, and 3.2 eV, respectively. The obtained materials were investigated for their photoluminescence (PL) and chromaticity characteristics to understand interfacial charge-transfer behavior. The PL spectra reveal broad blue - green emissions with main peaks located at 414 –437 nm for Mn 2 O 3 , 414 –439 nm for CuO, and a slightly red-shifted, intensified band at 435 nm for the Mn 2 O 3 /CuO composite. The corresponding CIE 1931 chromaticity coordinates (x ≈ 0.31, y ≈ 0.58) confirm a vivid green emission region, indicating improved color purity and radiative efficiency. These results demonstrate that coupling Mn 2 O 3 with CuO tailors the electronic band alignment, suppresses non-radiative losses, and promotes strong visible luminescence, making the Mn 2 O 3 /CuO nanocomposite a promising candidate for green light - emitting and optoelectronic devices.