Experimental and theoretical studies of the solid-state performance of electrodeposited Yb2O3/As2Se3 nanocomposite films

Highlights: • Polycrystalline nanocomposite films with sizes between 37.23 and 48.14 nm. • Films exhibited wide energy bandgap values ranging from 3.75 to 3.95 eV. • Multimode PL emissions in the UV–Vis–NIR regions. • Lone pair p-states of Se induced bandgap energy lowering. -- Abstract: The influence of the rare-earth oxide (Yb₂O₃) on arsenic selenide (As–Se) host is currently investigated and documented in this study. Nanocomposite films were grown using the electrodeposition (ED) technique with the addition of 1 – 4 mol% Yb₂O₃. The film's optical structural, optical, morphological, and electronic features were studied. The host matrix presents the monoclinic structure whereas the composite films present two phases –cubic and orthorhombic crystal structure. Crystallites within nano sizes (36.2 nm) were recorded for the pristine film while the composite films showed sizes ranging from 37.2 to 48.1 nm. Moreover, the Raman spectra revealed low energy Raman phonons characteristic of Se₈ rings, As₄Se₄ cages, As–Se hetero-polar bonds whose cleavage was due to the diffusion of the Yb ions into the host matrix as shown by the Raman shift. More so, the refractive index peaked at n = 2.66 in the λ interval of 350–600 nm, while the SEM images showed nano-balls and nanoclusters which are fairly homogeneous. PL studies exhibited multimode emission bands spanning the UV–Vis–NIR regions. First-principles calculations were employed to investigate the structural properties and electronic structure of the pristine (As–Se) film, as well as Yb contribution. It was found that Yb addition leads to reduce the bandgap energy and consequently the lone pair p-states of Se contribute nearby to Fermi energy level. Hence, the experimental and theoretical results of films afford potential applications in phase-change memory (PCM) and downconverting solar cell window layer.