Photovoltaic conversion and quantum efficiency in perovskite multiferroic ceramics

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. ,, …”

“…The open-circuit photovoltage (V oc ) is almost independent of the poling voltage sign and is ∼1.0 V, which is larger than ∼0.8−0.86 V in a 405 nm-irradiated ITO/(Bi 1-x Nd x )FeO 3 /Au device. 21 Figure 3d shows the characteristic curves under sunlight (AM1.5G spectrum) at a 10 2 mW/cm 2 intensity, indicating V oc ∼0.31 V for unpoled and poled states. J sc values are, respectively, about 5.2 × 10 2 , 5.5 × 10 2 , and 3.5 × 10 2 μA/ cm 2 for unpoled, +2, and −2 kV/cm poled states, which are larger than the J sc values in other electrode/BiFeO 3 /electrode devices under a white light.…”

“…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.…”

“…Remarkable photovoltaic (PV) conversion, photodetection, and electroluminescence have been reported recently in perovskite organic–inorganic lead halide materials. − However, stability problems under ambient atmosphere and the presence of Pb have raised concerns and will limit their application . 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

“…Photovoltaic power generation is the main form of using solar energy. Photogenerated carriers are produced inside photovoltaic materials upon light irradiation on their surface, which endows the photovoltaic materials with important potential applications in the fields of solar cells, photodetection, photocatalysis, and so on. − Traditional photovoltaic devices are usually obtained through the construction of a p–n junction, and a built-in electric field ( E b ) is formed at the junction. − The photogenerated electrons and holes are separated and form a photocurrent in those devices. However, the preparation of solar cells based on p–n junctions is complicated.…”