Doping effects on boron carbide quantum dots for solar cells application: DFT study

Abstract

The DFT method was used to explore the photovoltaic properties of nitrogen- and phosphorus-doped boron carbide quantum dots (BC₃QDs). Results showed chemical activity values of −5.512 eV for nitrogen-doped and −3.971 eV for phosphorus-doped BC₃QDs, with nitrogen-doped samples exhibiting higher chemical activity. Doping introduced mid-gap states, causing a red shift in the absorption spectra of 106 nm for nitrogen and 118 nm for phosphorus doping. Nitrogen doping (N-doping) enhanced charge transfer capabilities compared to phosphorus doping (P-doping). The nitrogen-doped BC₃QDs also displayed HOMO and LUMO energy levels (−5.373 eV and −2.103 eV, respectively) that are closer to TiO₂ and I⁻/I₃⁻, making them more compatible for solar cell applications by increasing electron injection, fill factor, light collection efficiency, and open-circuit voltage. Despite an improved energy conversion potential, the N-doped BC₃QDs’ efficiency (72.34 %) was impacted by rapid non-radiative recombination. These insights can guide the design of BC₃QDs in solar energy applications, photocatalytic devices, and QD nano-composites for energy harvesting.