Bandgap engineering of cobalt-doped bismuth ferrite nanoparticles for photovoltaic applications (original) (raw)
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Advances in Photovoltaic Behavior of Ferroelectric BiFeO 3
2016
Bismuth ferrite (BFO) is perhaps the only material that is multiferroic (ferroelectric, antiferromagnetic) at room temperature. In this review, its use in photovoltaic applications has been investigated. A low band gap (Eg ~ 2.2-2.7 eV) within the visible light range makes BFO a potential candidate for such application. We review recent progress in the observance of photovoltaic effect in BFO addressing the role of heterostructures, effect of doping and the role of domain and electrode in the photoresponse of BFO. Recent studies reveal the perovskite ferroelectrics are the promising materials for photovoltaic application. In the last few years, a considerable rise has been witnessed in the study of ferroelectric thin films. This can be attributed to the high open circuit voltages in these thin films. It has been observed that the physical mechanism of photovoltaic effect in ferroelectrics is still under observation /advancement as compared to the semiconductor conventional photovolt...
Materials
Ferroelectrics have recently attracted attention as a candidate class of materials for use in photovoltaic devices due to their abnormal photovoltaic effect. However, the current reported efficiency is still low. Hence, it is urgent to develop narrow-band gap ferroelectric materials with strong ferroelectricity by low-temperature synthesis. In this paper, the perovskite bismuth ferrite BiFeO3 (BFO) thin films were fabricated on SnO2: F (FTO) substrates by the sol–gel method and they were rapidly annealed at 450, 500 and 550 °C, respectively. The microstructure and the chemical state’s evolution with annealing temperature were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), and the relationship between the microstructure and electric, optical and photovoltaic properties were studied. The XRD, SEM and Raman results show that a pure phase BFO film with good crystallinity is obtained at a low ann...
Bandgap Tuning of Sm and Co Co-doped BFO Nanoparticles for Photovoltaic Application
Journal of Electronic Materials, 2018
Multiferroic BiFeO3 (BFO) with bandgap energy (Eg) between 2.2 eV to 2.7 eV is a potential candidate for photovoltaic (PV) application. However, the efficiency of BFO based PV solar cells is reportedly still too low (less than 2%) to be used for practical applications. Reducing Eg of BFO without compromising the ferroelectric properties is a big challenge to the scientific community to obtain power conversion efficiencies beyond the maximum value of 26.6% reported in general for silicon based hetero-structure PV solar cells. In this context, samarium (Sm) and cobalt (Co) co-doped BFO (Bi0:9Sm0:1Fe0:9Co0:1O3) nanoparticles were synthesized using the sol-gel method. X-ray diffractometry was employed to determine the structure of synthesized nanoparticles. A welldefined crystalline structure of co-doped BFO nanoparticles was confirmed. Field emission scanning electron microscopy was carried out to study grain morphology of synthesized nanoparticles. Sm and Co dopants have been shown to reduce grain size significantly from 68.3 nm to 18.5 nm. An UV-VisNIR spectrophotometer was used to measure diffuse reflectance to calculate Eg. A significant reduction of Eg down to 1.50 eV of co-doped BFO compared to undoped and or single doped counterpart has been manifested.
Photovoltaic Properties of Multiferroic BiFeO 3 /BiCrO 3 Heterostructures
Journal of the American Ceramic Society, 2014
We report a power conversion efficiency of~0.01% in multistacking of BiFeO 3 /BiCrO 3 bilayer thin films used as active layers in a photovoltaic (PV) device. The films were epitaxially deposited by pulse laser deposition onto (100) oriented CaRuO 3 -coated LaAlO 3 substrates and were subsequently illuminated with 1 sun (AM 1.5). The fill factor is determined to be 0.31%, a remarkable value for ferroelectric-and multiferroic-based PV devices. Our results demonstrate that photocurrent density and photovoltage can be tuned by varying the thickness and number of respective bilayers in the improvement of PV properties of multiferroic heterostructures. The maximum photocurrent is generated at an optimal multilayer thickness of 60 nm, with its origin being mainly ascribed to the contribution of ferroelectric polarization.
Structural and Optical Studies of Zinc doped BiFeO3 on the Bi-site
IOP Conference Series: Materials Science and Engineering, 2019
Zinc-doped bismuth ferrite (Bi 1-x Zn x FeO 3 , x = 0, 0.05, 0.1) powdered were synthesized through sol-gel auto combustion methods to investigate the optical properties while maintaining the whole structure of BiFeO 3 (BFO). The Zn doped induced the reveal of Bi 25 FeO 40 as a secondary phase and decreased the bond angle of Bi-O-Fe in the BFO phase structure which affect the electron density formation inside of the lattice. The presence of Zn content has also conducted the shifting of optical absorption in the UV-Vis region and increasing the dielectric constant value. This property is potent in visible light photonic applications.
Solid State Sciences 102 (2020) 106168, 2020
BiFe 1-x Co x O 3 (x ¼ 0.00, 0.01, 0.03, 0.05 and 0.07) nanoparticles (NPs), were prepared by ethylene-glycol-based sol-gel technique. Phase purity of the NPs was confirmed by x-ray diffraction (XRD) technique. The average size of pristine BiFeO 3 (BFO) NPs was found to be 46 nm, which initially increased to 50 nm for 1% Co doping and then decreases to 48, 45 and 43 nm for 3%, 5% and 7% Co-doped BFO NPs, respectively. X-ray photoelectron spectroscopy (XPS) and M€ ossbauer spectroscopy confirmed that the oxidation state of Fe and Co is þ3. In the low frequency region, the dielectric constant (ε') shows a maximum decrease by 96% (137 → 5.1) on 5% Co-doping concomitant with 62% decrease in dielectric loss (0.32 → 0.12) which indicates substantial reduction in leakage current density. Further, the pristine BFO shows a well-defined dielectric loss peak at 40 Hz (tan δ ¼ 0.4). In contrast, twin dielectric loss peaks are uniquely observed for all the Co doped BFO NPs. 1% doped NPs show first and second peaks at 7 Hz and 20,400 Hz, respectively, which shifts to higher frequencies of 245 Hz and 154,000 Hz, on 5% doping. The magnetic measurements (M À H) revealed the ferromagnetic behaviour of the NPs. On Co doping, saturation magnetization (M s) increased with decrease in coercive field (H c). A maximum enhancement of 226% (0.93 → 3.05 emu/g) in M s values concomitant with decline of 61% in H c values (80 → 15 Oe) was observed for 7% doping. The reduction in leakage current and enhancement of magnetic properties makes the NPs better-suited for device applications.
Electrical and structural properties of La doped BiFeO3
Nucleation and Atmospheric Aerosols, 2020
In this research work, the structural, electrical, dielectric and optical properties of 1.05 Bi1-xLaxFeO3(0.0 < x <0.05) nanoparticles have been reported. Sol-gel method was used to synthesize the nanoparticles. These materials have been analyzed by X-ray diffraction (XRD), dielectric measurements, P-E hysteresis loop measurements and UV-vis spectroscopy. The analysis of XRD spectra displayed rhombohedral structure at room temperature and the presence of few secondary phase formations. The average particle size of pure BFO and La-3%, 5% doped BFO was found to be decreasing from 53 nm to 29 nm with increasing La concentration. The effect of La subrogation on dielectric constant and dielectric loss of the samples was calculated at room temperature in a range of frequency 0 MHz-5 MHz. The ferroelectric measurements displayed that remnant polarization of La (3% & 5%) doped BFO were found to be about 0.60 μC/cm 2 at an applied field of 17.35 kV/cm and 56 μC/cm 2 at an applied field of 42.87 kV/cm at 50 Hz frequency. Weak ferroelectric effect has been observed for La doped BiFeO3 compound.
Photovoltaic effect in transition metal modified polycrystalline BiFeO 3 thin films
Journal of Physics D: Applied Physics, 2014
We report photovoltaic (PV) effect in multiferroic Bi 0.9 Sm 0.1 Fe 0.95 Co 0.05 O 3 (BSFCO) thin films. Transition metal modified polycrystalline BiFeO 3 (BFO) thin films have been deposited on Pt/TiO 2 /SiO 2 /Si substrate successfully through pulsed laser deposition (PLD). PV response is observed under illumination both in sandwich and lateral electrode configurations. The open-circuit voltage (V oc) and the short-circuit current density (J sc) of the films in sandwich electrode configuration under illumination are measured to be 0.9 V and −0.051 µA cm −2. Additionally, we report piezoresponse for BSFCO films, which confirms ferroelectric piezoelectric behaviour.
Journal of Applied Physics, 2020
Detailed studies of structural, dielectric, magnetic, ferroelectric, and optical properties of a chemically sol-gel synthesized series of Bi 1 − x Gd x Fe 1 − y Co y O 3 (x = 0, 0.1 and y= 0, 0.1) nanoceramics are presented. These nanoceramics attract attention as promising candidates for application as room temperature multiferroics in spintronics devices, exhibiting an optimistic set of properties. The average particle sizes of all the samples are calculated, and it was found to be ∼45 nm from the Scanning Electron Microscopy image. The dielectric behavior of the prepared nanoceramics was investigated over a wide frequency (100 Hz-10 3 kHz) and a temperature (35-350°C) range. Interestingly, a low temperature dielectric anomaly is observed at around 170°C for Bi 0.9 Gd 0.1 Fe 0.9 Co 0.1 O 3 due to the magnetoelectric coupling. A noticeably large value of dielectric constant (∼990) and a low tan δ loss have also been observed for this nanoceramic at room temperature. The complex impedance spectroscopic analysis was also performed by plotting Nyquist plots, and the corresponding activation energies are evaluated from the Arrhenius fittings. Magnetization measurements of the samples reveal the presence of weak ferromagnetism due to surface spins as well as a noticeable improvement in the magnetic properties with Gd and Co doping. Ferroelectric properties have also been observed to be slightly improved because of doping, though it becomes somewhat lossy for Gd and Co doped samples. All the promising improved properties directly depend on the subsequent increase in the bandgap from 2.29 eV to 2.45 eV, with doping in the parent BiFeO 3 compound confirmed from UV-Vis spectroscopy.