Remarkably enhanced photovoltaic effects and first-principles calculations in neodymium doped BiFeO3

Abstract

Remarkably enhanced photovoltaic effects have been observed in the heterostructures of p-type A-site Nd3+-doped BiFeO3 (Bi0.9375Nd0.0625)FeO3 (or BFONd) polycrystalline ceramics and the n-type ITO thin film. The maximum power conversion is ~0.82%, which is larger than 0.015% in BiFeO3 (BFO) under blue-ultraviolet irradiation of wavelength λ = 405 nm. The current-voltage (I-V) characteristic curve suggests a p-n junction interface between the ITO thin film and BFO (or BFONd) ceramics. The band gaps calculated from first-principles for BFO and BFONd are respectively 2.25 eV and 2.23 eV, which are consistent with the experimental direct band gaps of 2.24 eV and 2.20 eV measured by optical transmission spectra. The reduction of the band gap in BFONd can be explained by the lower electronic Fermi level due to acceptor states revealed by first-principles calculations. The optical calculations show a larger absorption coefficient in BFONd than in BFO.

Nanoscale excitonic photovoltaic mechanism in ferroelectric BiFeO3 thin films

“…14 It exhibits strong photostriction [15][16][17][18] and photovoltaic effects. 4,[11][12][13]19,20 In this paper combining measurements of time-resolved spectroscopy 21,22 and lattice distortion, [15][16][17][18] we correlate the dynamics of photocarrier and the microscopic piezoelectric response in phase-pure BiFeO 3 thin films. The results highlight a nanoscale transient lattice distortion that is distinctly different from that expected of the BPE.…”

Micro‐to‐nano domain structure and orbital hybridization in rare‐earth‐doped BiFeO3 across morphotropic phase boundary

“…Multiferroics which ferroelectric and magnetic parameters coexist, have inspired many studies to address the coupling effects and applications in multistate memory and photovoltaic devices . Bismuth ferrite BiFeO 3 (BFO) is the only known multiferroic material so far at and above room temperatures.…”

“…Multiferroics which ferroelectric and magnetic parameters coexist, have inspired many studies to address the coupling effects and applications in multistate memory 1,2 and photovoltaic devices. 3 Bismuth ferrite BiFeO 3 (BFO) is the only known multiferroic material so far at and above room temperatures. BFO has a perovskite rhombohedral R3c symmetry at room temperature, in which the anion sublattice distorts in a manner of the a À a À a À tilt system with the FeO 6 octahedral rotation in antiphase around the rhombohedral axis.…”

“…5 BFO has a G-type antiferromagnetic (AFM) ordering below N eel temperature (T N~6 40 K), in which each spin in the Fe 3+ ion is surrounded by 6 anti-parallel neighbor spins. 6,7 Many studies have focused on the A-site rare-earth (RE) substitution in BiFeO 3 to increase ferroelectric and magnetic responses. 8,9 The Curie temperatures (T C ) in (Bi 1Àx RE x )FeO 3 (RE = La, Nd, Sm, Gd) were predicted to decrease with decreasing A-site ionic polarizability and tolerance factor,…”

“…16 In (Bi 1Àx Sm x )FeO 3 system, a temperature-composition MPB between a coexistence (R3c and PbZrO 3 -like orthorhombic structures) and an orthorhombic Pnma symmetry was proposed for 0.09 ≤ x ≤ 0.14. 17 (Bi 1Àx Sm x ) FeO 3 show a predominantly ferroelectric R3c phase for x ≤ 0.12, a coexistence of ferroelectric triclinic and orthorhombic phases for 0.125 ≤ x ≤ 0.2, and a nonpolar orthorhombic phase for x ≥ 0.25. 9,18-20 A PbZrO 3 -type Pnam structure (with doubling unit cell along the c-direction) was reported in (Bi 1Àx Sm x )FeO 3 (x = 0.1 and 0.15) ceramics.…”