Understanding the optoelectronic and vibrational properties of MB4O7, using density functional theory, where M = Yb or Ce

This work aims to use density functional theory (DFT) and density functional perturbation theory (DFPT) to study the structure, optoelectronics, phonon dispersion and energetic stability of two new tetraborates, MB4O7, 4 O 7 , where M = Yb or Ce. The estimated values of the band gap energy (Eg) g ) and power conversion efficiency (PCE) for the systems were calculated. The Shockley-Queisser was also taken into account to measure the maximum theoretical efficiency of a photovoltaic source cell based on a p-n union. The estimated average gap energy values for the YbB4O7 4 O 7 and CeB4O7 4 O 7 systems, calculated using the GGA-PBE, HSE06, and GGA+U functionals, were 3.64 eV and 0.97 eV, respectively. The average PCEs calculated for the YbB4O7 4 O 7 and CeB4O7 4 O 7 systems were 11.28% and 25.66%, respectively. The PCE and energy stability suggest that CeB4O7 4 O 7 may be a more viable candidate for a solar device than YbB4O7, 4 O 7 , at least in terms of these specific parameters. The results reported here, as well as those related to absorption calculations, showed that the structures have optical responses in the visible region, suggesting that both systems can be used as optoelectronic devices and in solar cell designs.