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Journal ArticleDOI

Polarization controlled photovoltaic and self-powered photodetector characteristics in Pb-free ferroelectric thin film

24 Jan 2019-APL Materials (AIP Publishing LLCAIP Publishing)-Vol. 7, Iss: 1, pp 011106
TL;DR: In this article, a switchable and large PV effect is demonstrated in a Pb-free ferroelectric 0.5Ba(Zr0.7Ca0.2Ti0.3)TiO3 (BZT-BCT) thin film fabricated by a pulsed laser deposition technique.
Abstract: Ferroelectrics are considered next generation photovoltaic (PV) materials. In this work, a switchable and large PV effect is demonstrated in a Pb-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) thin film fabricated by a pulsed laser deposition technique. The material shows a remarkable PV output of 0.81 V due to its morphotropic phase boundary composition. The observed PV effect is analyzed on the basis of the interfacial Schottky barrier and bulk depolarization field. The poling dependent PV studies revealed that although the Schottky and depolarization field contribute to the PV effect, the latter dominates the PV response beyond the coercive field. Additionally, the importance of this compound in the field of a self-biased photodetector is elucidated in terms of calculated photodetector parameters such as responsivity and detectivity. The explored results will bring significant advancement in the field of ferroelectric PV, UV solid state detector applications and also give an additional dimension to the multifunctional ability of the BZT-BCT system.

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Citations
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Journal ArticleDOI
TL;DR: In this paper, the photoinduced dielectric, pyroelectric, and ferroelectric properties of a lead-free lead free oxide were carried out in out-of-plane and in-plane geometry.
Abstract: The recent renaissances in the field of ferroelectric oxides are owing to various photoinduced phenomena. However, the microscopic correlations among various photoinduced physical characteristics are essential for a detailed understanding of the dynamics associated with these phenomena. In this work, the photoinduced dielectric, pyroelectric, and ferroelectric properties of a lead-free $\mathrm{B}{\mathrm{a}}_{0.875}{(\mathrm{B}{\mathrm{i}}_{0.5}\mathrm{L}{\mathrm{i}}_{0.5})}_{0.125}\mathrm{Ti}{\mathrm{O}}_{3}$ ferroelectric oxide are carried out in out-of-plane and in-plane geometry. The dielectric studies under 405-nm light illumination revealed a significant change in dielectric permittivity along with a decrease in Curie temperature. The observed effects are attributed to the change in internal field distribution inflicted by the photogenerated nonequilibrium charge carriers and trapped charges. The sample exhibits a photoinduced significant change in pyroelectric current and the associated polarization. These effects demonstrate that light could be used as an additional degree of freedom to influence the ferroelectric order parameter. The observed photoinduced dielectric and ferroelectric characteristics give the experimental evidence for the theoretical formalism on the photoinduced ferroelectric phenomena. In addition, the Rayleigh analysis performed on this system highlights the strong correlation between the observed photoferroelectric characteristics with the Rayleigh parameters. These findings could widen the understanding of the photoferroelectric characteristics to extend its applications toward advanced optoelectronic devices.

10 citations

Journal ArticleDOI
TL;DR: In this paper, the authors highlight improved photosensing performance in ITO/ (Bi 0.93 Sm 0.07 ) FeO 3 /Au heterostructure through a prior electric field poling.

10 citations

Journal ArticleDOI
TL;DR: In this paper, a self-powered deep UV photodetector based on a Ga2O3/BFO heterojunction is fabricated via solution spin-coating and metal-organic chemical vapor deposition (MOCVD) methods.
Abstract: Ga2O3 is one of the most suitable semiconductor materials for performing deep UV photoelectric detection. In this work, a self-powered deep UV photodetector based on a Ga2O3/BFO heterojunction is fabricated via solution spin-coating and metal-organic chemical vapor deposition (MOCVD) methods. Without biasing driven, the device achieves an extreme low dark current ( ${I}_{dark}$ ) of 8.38 fA, a photo-to-dark current ratio ( PDCR ) of $1.66\times10$ 5, a high specific detectivity ( ${D} \ast $ ) of $6.1\times 10^{12}$ Jones and an open-circuit voltage ( ${V}_{\textit {oc}}$ ) of 0.55 V responding to deep UV irradiation (254 nm in this work). Through analyzing the band diagram of the heterojunction, the intrinsic physical characteristics of the photodetector are discussed. Results show that the photodetector has excellent deep UV signal detecting ability, indicating that Ga2O3/BFO heterojunction is a potential candidate for performing self-powered deep UV photodetection.

8 citations

Journal ArticleDOI
TL;DR: In this paper , a multiscale polarity structure optimization strategy was proposed to improve the performance of self-powered photodetectors in a hexagonal Y 0.95 Bi 0.05 MnO 3 (YBMO5) with a wide band ranging from ultraviolet to near infrared.

8 citations

Journal ArticleDOI
TL;DR: In this paper, the anomalous photovoltaic effect and resistive switching behaviors in ferroelectric materials attract much attention in recent years, and the conductive mechanisms and research progresses of the two effects were discussed in this study.
Abstract: The anomalous photovoltaic effect and resistive switching behaviors in ferroelectric materials attract much attention in recent years. Dozens of researches revealed that the two effects coexist and affect each other in electrode/ferroelectric/electrode structures. Therefore, the conductive mechanisms and research progresses of the two effects were discussed in this study, which suggested the interface coupling effect caused by polarization states led to switchable photovoltaic and different resistance states. On the other hand, electrode/ferroelectric/electrode structures have great potential in the application of high-density memories, and a novel non-volatile optoelectronic memory which can write multiple storage states and read information non-destructively can be realized by exploiting the two effects properly.

7 citations

References
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Journal ArticleDOI
TL;DR: The use of a solid hole conductor dramatically improved the device stability compared to (CH3NH3)PbI3 -sensitized liquid junction cells.
Abstract: We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH3NH3)PbI3 as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI2 and deposited onto a submicron-thick mesoscopic TiO2 film, whose pores were infiltrated with the hole-conductor spiro-MeOTAD. Illumination with standard AM-1.5 sunlight generated large photocurrents (JSC) exceeding 17 mA/cm2, an open circuit photovoltage (VOC) of 0.888 V and a fill factor (FF) of 0.62 yielding a power conversion efficiency (PCE) of 9.7%, the highest reported to date for such cells. Femto second laser studies combined with photo-induced absorption measurements showed charge separation to proceed via hole injection from the excited (CH3NH3)PbI3 NPs into the spiro-MeOTAD followed by electron transfer to the mesoscopic TiO2 film. The use of a solid hole conductor dramatically improved the device stability compared to (CH3NH3)PbI3 -sensitized liquid junction cells.

6,751 citations

Journal ArticleDOI
TL;DR: It is predicted that the single-crystal form of the MPB composition of the present system may reach a giant d(33) = 1500-2000 pC/N, which may provide a new recipe for designing highly piezoelectric materials (both Pb-free and P b-containing) by searching MPBs starting from a TCP.
Abstract: We report a non-Pb piezoelectric ceramic system Ba(Ti(0.8)Zr(0.2))O(3)-(Ba(0.7)Ca(0.3))TiO(3) which shows a surprisingly high piezoelectric coefficient of d(33) approximately 620 pC/N at optimal composition. Its phase diagram shows a morphotropic phase boundary (MPB) starting from a tricritical triple point of a cubic paraelectric phase (C), ferroelectric rhombohedral (R), and tetragonal (T) phases. The high piezoelectricity of the MPB compositions stems from the composition proximity of the MPB to the tricritical triple point, which leads to a nearly vanishing polarization anisotropy and thus facilitates polarization rotation between 001T and 111R states. We predict that the single-crystal form of the MPB composition of the present system may reach a giant d(33) = 1500-2000 pC/N. Our work may provide a new recipe for designing highly piezoelectric materials (both Pb-free and Pb-containing) by searching MPBs starting from a TCP.

2,197 citations

Journal ArticleDOI
03 Apr 2009-Science
TL;DR: It is found that bulk electric conduction in ferroelectric monodomain BiFeO3 crystals is highly nonlinear and unidirectional.
Abstract: Unidirectional electric current flow, such as that found in a diode, is essential for modern electronics. It usually occurs at asymmetric interfaces such as p-n junctions or metal/semiconductor interfaces with Schottky barriers. We report on a diode effect associated with the direction of bulk electric polarization in BiFeO3: a ferroelectric with a small optical gap edge of ∼2.2 electron volts. We found that bulk electric conduction in ferroelectric monodomain BiFeO3 crystals is highly nonlinear and unidirectional. This diode effect switches its direction when the electric polarization is flipped by an external voltage. A substantial visible-light photovoltaic effect is observed in BiFeO3 diode structures. These results should improve understanding of charge conduction mechanisms in leaky ferroelectrics and advance the design of switchable devices combining ferroelectric, electronic, and optical functionalities.

1,610 citations

Journal ArticleDOI
TL;DR: A fundamentally different mechanism for photovoltaic charge separation is reported, which operates over a distance of 1-2 nm and produces voltages that are significantly higher than the bandgap.
Abstract: In conventional solid-state photovoltaics, electron-hole pairs are created by light absorption in a semiconductor and separated by the electric field spaning a micrometre-thick depletion region. The maximum voltage these devices can produce is equal to the semiconductor electronic bandgap. Here, we report the discovery of a fundamentally different mechanism for photovoltaic charge separation, which operates over a distance of 1-2 nm and produces voltages that are significantly higher than the bandgap. The separation happens at previously unobserved nanoscale steps of the electrostatic potential that naturally occur at ferroelectric domain walls in the complex oxide BiFeO(3). Electric-field control over domain structure allows the photovoltaic effect to be reversed in polarity or turned off. This new degree of control, and the high voltages produced, may find application in optoelectronic devices.

1,434 citations

Journal ArticleDOI
TL;DR: An explanation of the photovoltaic effect, based on the asymmetry of the lattice, is proposed in this paper, which accounts for the light-induced index changes in LiNbO3.
Abstract: Photocurrents in doped LiNbO3 crystals are shown to be due to a bulk photovoltaic effect with saturation voltages in excess of 1000 V (∼105 V/cm). This effect accounts for the light‐induced index changes in LiNbO3. An explanation of the photovoltaic effect, based on the asymmetry of the lattice, is proposed.

1,053 citations