Microwave-sintering enhanced photovoltaic conversion in polycrystalline Nd-doped BiFeO3

Enhancing Photovoltaic and Photosensing Performances in Bismuth Ferrite via Polar Order Engineering

“…The VBM and CBM in the rhombohedral BiFeO 3 structure correspond to the highest state of the O 2 p orbital and the lowest state of the Fe 3 d orbital, respectively. The extrapolated dashed lines (as shown in Figure a) for unpoled and 2 kV/cm poled Specimens indicate a similar bandgap of E g ∼2.16 eV, which agrees with the theoretical bandgap values of E g ∼2.15 eV in BiFeO 3 and E g ∼2.11–2.23 eV in Nd - doped BiFeO 3 ceramics. ,, …”

“…α, h, and ν are, respectively, the absorption coefficient, Planck's constant, and photon frequency. The absorption coefficient α was calculated using transmission (T) and the relation, , 20,21,26 To probe the E-field poling effects in orbital hybridizations, Fe L 3 -edge and oxygen K-edge synchrotron XAS spectra were collected for unpoled and 2 kV/cm poled specimens as shown in Figure 2b,c, including the Fe 2 O 3 powder. The Fe L 3 -edge absorption is due to the Fe 2p−3d transition.…”

“…Ferroelectric (FE) BaTiO 3 -based materials have demonstrated promising photoresponsivity and detectivity for self-powered photodetectors. − Among the lead-free perovskite FE and multiferroic materials, PV conversion in BiFeO 3 has become an emerging topic for solar energy harvesting, capacitive energy storage, photoelectrochemical conversion, FE polarization sensors, and photodetectors − due to exceeding the Shockley–Queisser limit, small bandgaps (∼2.0–2.8 eV), − and semiconducting features . Various approaches to modify domain patterns, polarization, and atomic hybridization have been attempted to improve PV conversion by elemental substitution, defect manipulation, electric ( E ) poling, and microwave sintering. ,− …”

Photovoltaic Effect Induced by Self-Polarization in BiFeO3 Films

“…Ferroelectric materials have attracted much attention in the field of photovoltaics as the open-circuit voltage is not limited by their band gap and also due to their high photoelectric conversion efficiency. − At the same time, E b generated by the electric dipole in ferroelectric materials facilitates separation of the photogenerated carriers during the process of the photovoltaic effect (PE). − Among many ferroelectric materials, BiFeO 3 (BFO) is one of the key research materials because of its large remanent polarization (∼100 μC/cm 2 ) and high Curie temperature (∼810 °C). Moreover, it has significant absorption of visible light due to its narrow band gap (∼2.2 eV), which is beneficial for the development of solar energy devices. − However, there are many factors affecting the photovoltaic performance of BFO, which leads to a controversy about its photovoltaic mechanism. Some studies found that the PE of BFO is related to a polarization electric field.…”