Novel white light-emitting CdSe:Mn²⁺ synthesized by photo-assisted chemical bath deposition

Nowadays, white light-emitting materials have attracted extensive research due to their potential applications in lighting devices and displaying images. Several semiconductor nanoparticles have been explored to achieve efficient white light emission. In this work, we report on novel white light-emitting CdSe:Mn²⁺ thin films synthesized by photo-assisted chemical bath deposition. The effect of varying the Mn²⁺ ion concentrations on the thin film structure, morphology, and optical properties was investigated. X-ray powder diffraction results indicated that all the films annealed at 250 °C possessed a cubic structure, with crystallite sizes in the range of 1–130 nm. Scanning electron microscopy demonstrated spherical nanoparticles with no significant changes with varying Mn²⁺ doping concentrations. Energy dispersive X-ray spectroscopy confirmed the presence of the anticipated elements. The atomic force microscope revealed that the surface roughness has decreased with an increase in Mn²⁺ ion concentrations but decreased for 0.7 %Mn²⁺. The UV–Vis absorption spectra showed absorption edges around 600–650 nm. Photoluminescence emission spectra excited at 3.8 eV (325 nm) showed emission bands at around 1.75 eV (709 nm), and 1.88 eV (659 nm), which were attributed to the band-to-band emission, and ⁴T₁(⁴G)→⁶A₁(⁶S) transitions of Mn²⁺ ions, respectively, while emission bands at 2.35 eV (528 nm), and prominent at 3.17 eV (391 nm) were due to the glass substrate. The temperature-dependent luminescence showed a decrease in relative emission intensity with the increase in the operating temperature. The chromaticity colour coordinates showed white light-emitting thin films. These present findings open a new door to developing white light using CdSe thin films.