Bandgap engineering of cobalt-doped bismuth ferrite nanoparticles for photovoltaic applications

[摘要] The bandgap energy range of multiferroic bismuth ferrite is 2.2–2.7 eV, making it a promising candidate for photovoltaic (PV) applications. But its efficiency is still very low (<2%). This report thus focusses on the application ofbismuth ferrite (BFO) engineered with cobalt (Co) doping and on the tuning of its bandgap energy ($E_g$). BiFeO$_3$ is a unique multiferroic material that simultaneously displays both ferromagnetic and ferroelectric properties at room temperature. Co doped with pure BiFeO$_3$ (BiFe$_{(1−x)}$Co$_x$O$_3$; $x = 0$, 0.05, 0.1 and 0.15) was synthesized by the sol–gel method andannealed at 600$^{\circ}$C. X-ray diffraction shows the well-arranged crystalline structure and peaks of pure and doped-BiFeO$_3$ nanoparticles. A suitable reduction of $E_g$ has been observed for Co-doped BiFeO$_3$, which may be appropriate for the effective use in PV solar cells. Thermogravimetric analysis and differential scanning calorimetry were used to investigate the thermal decomposition character of the xerogel powder and the pattern of pure and doped BiFeO$_3$ phases. Field emission scanning electron microscopy images showthe surface crystallography of pure and Co-doped BiFeO$_3$. Co-doped BiFeO$_3$ has considerably reduced the crystallite and particle size of the samples. We have calculated the $E_g$ of pure and doped BiFeO$_3$ using a UV–Vis–NIR spectrophotometer and the results show the important reduction of $E_g$ (1.60 eV) of the Co-doped samples, which may have potential applications in PV solar cells.

[学科分类] 材料工程

[关键词] Bandgap;multiferroic;nanoparticles;photovoltaic cells;sol–gel.