Abstract
The photovoltaic (PV) effect in polar materials offers great potential for lightenergy conversion that generates a voltage beyond the bandgap limit of present semiconductorbased solar cells. Ferroelectrics have received renewed attention because of the ability to deliver a high voltage in the presence of ferroelastic domain walls (DWs). In recent years, there has been considerable debate over the impact of the DWs on the PV effects, owing to lack of information on the bulk PV tensor of host ferroelectrics. In this article, we provide the first direct evidence of an unusually large PV response induced by ferroelastic DWs—termed ‘DW’PV effect. The precise estimation of the bulk PV tensor in single crystals of barium titanate enables us to quantify the giant PV effect driven by 90° DWs. We show that the DWPV effect arises from an effective electric field consisting of a potential step and a local PV component in the 90° DW region. This work offers a starting point for further investigation into the DWPV effect of alternative systems and opens a reliable route for enhancing the PV properties in ferroelectrics based on the engineering of domain structures in either bulk or thinfilm form.
Introduction
The photovoltaic (PV) effect in polar materials has attracted substantial interest, because the photoconversion mechanism can be exploited for the development of advanced solar cells that generate a high voltage. The bulk PV effect has been extensively studied in ferroelectric oxides^{1,2,3,4,5,6,7,8}, compound semiconductors^{9,10} and fluoride polymers^{11}. The introduction of transitionmetal atoms into the host lattices has been shown to be effective in enhancing the bulk PV effect under visiblelight irradiation, because defect states in the bandgap result in light absorption and the subsequent charge separation^{5,12}.
Recent studies on ferroelectric thin films have demonstrated that bismuth ferrite (BiFeO_{3}: BFO) with ferroelastic domain walls (DWs) delivers abovebandgap voltages that can be tuned by the number of the DWs^{13}. An internal quantum efficiency in the DWs has been reported as high as 10%^{14}. The microscopic origin of the high photovoltage is shown to originate from an electrostatic potential step at the DWs. Meanwhile, the temperaturedependent PV studies have revealed that BFO films generate a high photovoltage by controlling the conductivity of the DWs^{15}. This anomalous PV effect is thought to be due to the bulk PV effect, not to the electrostatic potential step at the DWs. Essentially, the bulk PV effect arises from spatial symmetry breaking in polar materials^{16,17} and can be described in terms of the bulk PV tensor^{18}. Recent theoretical calculations^{19,20,21,22} and atomicscale microscopy^{23,24} have shown that spatial symmetry breaking is preserved in the local region of the ferroelastic DWs. These studies suggest that the DW region inherently has a local PV component similar to the bulk PV effect in addition to the electrostatic potential step.
Until now, there has been considerable debate over the mechanism of the PV effects in ferroelectrics in the presence of ferroelastic DWs, owing to lack of information on the bulk PV tensor of the host crystals. In this article, we present the first direct evidence that ferroelastic DWs deliver an anomalously large PV response in a perovskite ferroelectric crystal. We term it the ‘DW’PV effect. We select barium titanate (BaTiO_{3}: BT) as a model system to investigate these effects. The precise estimation of the bulk PV tensor allows us to quantify the contribution of 90° DWs in BT single crystals, revealing that the field strength due to the DWPV effect is far beyond the bulk PV effect. We show that this extremely large field stems from an effective electric field consisting of a potential step and a local PV component in the 90° DW region.
Results
We evaluated the PV properties of the single crystals of Mndoped BT (MnBT) in three different configurations shown in Fig. 1. The electronic mechanism of the photocurrent properties under visiblelight irradiation in MnBT has been reported in ref.^{12}. Here, we focus on the impact of 90° DWs on the PV properties. Throughout this paper, we denote photocurrent density vector by J, bias voltage by V_{bias}. We define shortcircuit current density (J_{SC}) as the J value at V_{bias} = 0 and opencircuit voltage (V_{OC}) as the V_{bias} value at J = 0.
J  V_{bias} characteristics
Figure 2a2b represent the J  V_{bias} characteristics of the MnBT samples in the J//[001] and the J//[011] configurations, respectively, under light irradiation (3.11 eV, Θ = = 90°). In the both configurations, we confirmed a linear relation between J and V_{bias}. It is worth noting that the signs of J_{SC} and of V_{OC} are different between the J//[001] and the J//[011] configurations. That is, the photocurrent flows in the direction opposite to the spontaneous polarization (P_{s}) in the singledomain state (Fig. 2a) whereas the photocurrent is generated in the same direction as the net spontaneous polarization in the 90° domain structure (Fig. 2b).
In Fig. 2c2d we plot the light intensity dependences of J_{SC} and opencircuit electric field (E_{OC}). While J_{SC} is proportional to , E_{OC} saturates in the high region above ~1 W/cm^{2}. Hereafter we discuss this high region, where the dark conductivity is negligible.
Values of the photoconductivity, , estimated from the slope of the J  V_{bias} data (Fig. 2a,b) are proportional to and the proportional constants in both configurations are tabulated in Table 1. We note that is almost the same in both the configurations. The 90° DWs that are present in the J//[011] samples do not affect the overall behaviour of σ_{ph}. This experimental result provides the fundamental basis for identifying the DWPV effect, as described below.
Lightpolarization dependence of J_{SC}
In Fig. 3 we plot the shortcircuit photocurrent density normalized by the light intensity observed for the MnBT samples in the J//[001] and the J//[011] configurations. In both of the configurations we could confirm a strong dependence of J_{SC} on the lightpolarization.
According to the bulk PV tensor in the tetragonal BT system [see Eq. (5) in Method], the photocurrent density in the J//[001] configuration can be written by
The fitting of the data shown in Fig. 3a leads to nA/W and nA/W at eV. The standard deviations of these parameters are shown in parenthesis and estimated to be ~5% at most.
From the results measured in the J//[010] configuration (Fig. 1b) we conclude that is smaller than the detection limit of our measurement system, i.e., ~3 pA/W. Since the value of ~3 pA/W is two orders of magnitude smaller than those of other components and , we neglect β_{15} throughout this paper.
In the J//[011] configuration (Fig. 3b) we found that the photocurrent flows in the same direction as , which cannot be explained by the bulk PV effect as described below. The poling in the J//[011] configuration leads to a domain structure in which two kinds of spontaneous polarizations (P_{s1} and P_{s2}) with different orientations are present with the 90° DWs. The photocurrent density in the J//[011] configuration arising from the bulk PV effect can be expressed by
which is independent of the lightpolarization . The derivation of Eq. (2) based on effective electric fields is given in Supplementary Information.
In Fig. 3b we also put the contribution of expected from Eq. (2). We note a considerable component of positive J_{SC} with a strong dependence on , which goes beyond the bulk PV effect with a negative constant . The experimental fact that takes almost the same value regardless of the presence or absence of the DWs leads us to consider that the dependent, positive is not relevant to σ_{ph}. These results strongly support the conclusion that the behaviour of J_{SC}//[011] does originate from the 90° DWs. The thickness (w_{DW}) of the 90° DW region is reported to be 2–100 nm^{25,26,27,28,29,30}. Since w_{DW} is two to three orders of magnitude smaller than the DW spacing (W ~ 15 μm), the large value of J_{SC}//[011] appears to arise from a giant PV effect in the local region of the 90° DWs.
We define as the difference between the measured and the bulk PV effect . Using the following functional form: , where β_{DW0} and β_{DW1} correspond to the positive offset and the amplitude, respectively, the fitting yields nA/W and nA/W. We emphasize that is not calculated locally in the DW region but is averaged over the entire samples.
The bulk PV effect vs. the DWPV effect
The results measured at three wavelengths (λ = 405, 515 and 639 nm) are summarized in Table 2. Here we focus on the positive offset and the bulk PV effect of the MnBT samples, which are plotted as a function of hv in Fig. 4a. Except for the data at hv = 1.97 eV, which are comparable to the detection limit of ~3 pA/W, we note that is 5–10 times as large as .
As described above, we found that σ_{ph} does depend neither on the lightpolarization nor on the crystal orientation nor on the presence/absence of the DWs. We can thus express J_{SC} using effective electric field as and define the effective electric field for representing the PV effect by
Here is equivalent to for the bulk PV effect and to for the DWPV effect, where β corresponds to its respective and β_{DW0}. Considering the linear current  voltage characteristics and the independence of on , is identical to the opencircuit electric field (E_{OC}).
In Fig. 4b we plot the and values as a function of hv. We found that does not depend on hv, which seems to be a specific feature of the bulk PV effect. Even though the DWPV effect occurs in an extremely small volume only in the 90° DW region, the resultant effective field averaged over the entire samples is large compared with . These experimental results provide direct evidence that the 90° DWs deliver a giant PV effect. Taking into account that is significantly small at 1.97 eV and that indicates a sharp decrease in the hv range of 2.0–2.5 eV, we speculate that the DWPV effect due to β_{DW0} is activated at above a threshold of hv, the reason of which is still under investigation.
Discussion
The bulk PV effect stems from an asymmetry in the photogenerated carrier dynamics in polar materials and can be interpreted in terms of effective electric fields. We introduce a single parameter (γ) representing the asymmetry in the photogenerated carrier density and relate the effective electric field ( = J_{SC}/σ_{ph}) with γ as
Here n and p denote electron density and hole density, μ_{e} and μ_{h} their mobilities. We also define and as the averaged drift velocities projected onto the P_{s} direction where the average is taken over a solid angle of 2π. The derivation of Eq. (4) is given in Supplementary Information. As shown in Fig. 4b is almost independent of hv. Based on this result it is reasonable to assume that in the [011] configuration the γ value does not depend on hv even though and σ_{ph} are strongly dependent on hv.
The carrier dynamics under steadystate conditions can be interpreted in terms of electrochemical potential^{31}. We first discuss the effective electric field arising from the DWPV effect using the electrochemical potential gradient. Noting that V/cm is averaged over the entire samples with the 90° domain structure (W~ 15 μm), we can regard the net photovoltage per DW as ~37.5 mV. The 90° DW region indeed has a significant volume with a w_{DW} of 2–100 nm^{25,26,27,28,29,30}. Adopting w_{DW} ~ 10 nm as a representative value, we estimate the corresponding effective electric field in the DW region, , to be ~37.5 kV/cm. This field strength is quite large, i.e., 8000–8500 times as large as that inside the domains V/cm).
One of the key factors affecting in the 90° DW region is electrostatic potential step ^{20}. A rotation of the P_{s} vector in the 90° DW region is accompanied by ^{22}. The variation in P_{s} normal to the DW results in an electric double layer, yielding at each of the DW. Another factor affecting is a local PV component peculiar to the 90° DW region. The DW region has the noncentrosymmetric nature, i.e., a ferroelectric polarization to a considerable degree. The substantial strain in the 90° DW region with forces us to consider a local PV component, which appears to be greatly different from those inside the domain, i.e., from the bulk PV tensor. In fact, the large dependence of on the lightpolarization shown in Fig. 3b (corresponding to β_{DW1}) is not predicted by . Furthermore, the experimental fact of the large β_{DW0} value with an oscillation due to β_{DW1} validates the local PV component of the 90° DW region, which is clearly distinct from the bulk PV effect. Therefore, we take into account the following two factors affecting in the 90° DW region: and the local PV component.
First we assessed the effect of on . According to the firstprinciples calculations^{20}, is estimated to be ~230 mV in the 90° DW in the tetragonal BT system. Under light irradiation, is partially screened by the photogenerated carriers. A detailed study including the screening of has been performed for BFO films based on a drift diffusion analysis^{14}. We estimate the electrostatic potential step involving the screening effect, i.e., the screened electrostatic potential step to be ~50 mV at least, which is still larger than the experimental value of mV. Our estimation focusing on the carrierdensity dependence of chemical potential is given in Supplementary Information.
Next we investigated the effect of the local PV component on . As described above, the noncentrosymmetric structure in the 90° DW region does produce the local PV component, which is superimposed on . Assuming w_{DW} ~ 10 nm, we estimate the effective electric field originating from the local PV component in the 90° DW region to be kV/cm.
We point out that the local PV component in the DW region can also explain the anomalous PV properties reported for BFO films. In the original report, Yang et al. have observed that V_{OC} increases in proportion to the number of the 71° DWs between electrodes^{13}. They have proposed a model in which is the origin of the PV properties, together with the fact that a V_{OC} evaluated for each DW of ~10 mV is quite close to a potential step across the 71° DW of 20 mV^{14,21}. In contrast, Bhatnagar et al. have observed that V_{OC} markedly increases at low temperatures and that J_{SC} depends on the lightpolarization, both of which cannot be explained only by . The behaviour of V_{OC} and J_{SC} is due not to but to the bulk PV effect and the bulk PV tensor was evaluated from the sinusoidal components in ^{15}. The data observed in contain not only the sinusoidal component but also an apparently significant constant term. In their analysis, this constant term is thought to be caused by the combined effect of the experimental misalignments and is not taken into consideration. We infer that the DWPV effect also contributes to the observed behaviour. The DWPV effect involving and the local PV component provides a reasonable explanation for the PV data reported for the BFO films, which are associated with both the number of DWs on the one hand^{13} and the bulk PV nature (the strong lightpolarization dependence) on the other^{15}.
Finally, we discuss why the DWPV effect delivers a large positive photocurrent going beyond the negative bulk PV effect, i.e., . Figure 5 depicts the schematic diagram of valence band maximum (VBM) and conduction band minimum (CBM) under the opencircuit condition. The bulk PV and the DWPV effects are incorporated as the effective electric fields. Although electronic band structures are modulated by the strain in the 90° DW regions, the modulation is assumed to be ~20% at most, as has been reported for 71° DW in BFO. Since the band modulation caused by the strain is much smaller than the influences of and the local PV component, we represent the CBM and the VBM as the two parallel segments. Given a lightpolarization angle of +45°, the effective electric fields inside the domains are described as and , where and denotes those ascribed to β_{31} and β_{33}, respectively. The electric field in each domain varies with the lightpolarization angle while the averaged field V/cm is independent of . As described above, the effective electric field in the 90° DWs region V/cm) and the DW spacing (W ~ 15 μm) lead to the net photovoltage per DW of ~37.5 mV, which is the sum of the value and the local PV component. Noting that the magnitude of (positive) is larger than that of (negative), we estimate the net PV field in the [011] direction, , to be ~+ 20.5 V/cm (the red dasheddotted line in Fig. 5). Since the positive field arising from the DWPV effect overcomes the negative field due to the bulk PV effect, the shortcircuit current is reversed by the introduction of the 90° DWs.
We emphasize that the DWPV effect can be assessed by examining the PV properties based on the precise estimation of the bulk PV tensor. Our report on the giant DWPV effect opens a reliable route for enhancing the PV properties in ferroelectrics based on the engineering of domain structure in either bulk or thinfilm form.
Method
Sample preparation
The samples were prepared from commercial BT single crystals (Neotron) and a Mn(0.25%)doped BT bulk single crystal grown by a topseeded solution growth method in our group. The image of the MnBT crystal is given in Supplementary Information. After cutting the crystals, we polished the top and bottom sides of the samples [the (100) and surfaces] and annealed them in air at 1250 °C for 12 h for recovery from mechanical damage incurred during the sample preparation. Electrodes were fabricated on the lateral sides by platinum sputtering. The poling was performed at an applied electric field of 2 kV/cm during a slow cooling from 150 °C down to room temperature through the Curie temperature (T_{C} ~ 130 °C).
Electrode configurations
Figure 1 depicts the electrode configurations that we conducted the PV measurements. In all configurations, visible light was irradiated along the direction, which is perpendicular to the top surface. In the J//[001] configuration (Fig. 1a) the electrodes on the (001) and surfaces were used for the poling and the PV measurements. The photocurrent was measured along the [001] direction in the singledomain samples. In the J//[010] configuration (Fig. 1b) the poling was performed along the [001] direction while the photocurrent was measured along the [010] direction. In the J//[011] configuration (Fig. 1c) the electrodes on the (011) and surfaces were used for the poling and the PV measurements. The poling yielded a 90° domain structure where two kinds of spontaneous polarizations (P_{s1} and P_{s2}) with different orientations are present. Using optical microscopy and piezoelectric force microscopy (PFM), we confirmed that the spacing between the 90° DWs was ~15 μm for both the MnBT and BT samples. The typical PFM image of the domain structure is given in Supplementary Information. The photocurrent was measured along the direction of the net spontaneous polarization , i.e., the [011] direction.
PV measurements
The PV properties were measured at 25 °C. We denote photocurrent density vector by J and bias voltage by V_{bias}. We measured the current  voltage characteristics under visible light irradiation with an intensity of 0.03–3 W/cm^{2} using three monochromatic laser modules [wavelength (photon energy hv); 405 nm (3.11 eV), 515 nm (2.45 eV) and 639 nm (1.97 eV)]. In the measurement of the PV properties, we excluded a transient current due to the capacitance and resistance of the samples. We also confirmed that currents arising from both the pyroelectric and piezoelectric effect are eliminated thoroughly under the measurement conditions in the steady state.
As indicated by the arrows in Fig. 1, the positive direction of J and V_{bias} is defined as that of the net spontaneous polarization, P_{s} (Fig. 1a,b) or (Fig. 1c). In Fig. 2a,b the measured current density (J) is plotted as a function of V_{bias}. We define shortcircuit current density (J_{SC}) as the J value at V_{bias} = 0 and opencircuit voltage (V_{OC}) as the V_{bias} value at J = 0. In determining V_{OC} we extrapolated the linear J  V_{bias} characteristics in a limited range owing to the current amplifier used in our study. It is noteworthy that the positive/negative of V_{OC} means the opposite/same direction of the photovoltage generated inside the samples, because the opencircuit condition is achieved when V_{bias} cancels V_{OC} under light irradiation.
We define light intensity as the light power per unit area and denote opencircuit electric field (E_{OC}) by the opencircuit voltage (V_{OC}) divided by the electrode spacing. The light polarization was controlled by a halfwavelength plate and a polarizer. We represent the lightpolarization (Θ or as the angle between the polarization plane of light and the measured direction of J, as illustrated in Fig. 1.
Tensor representation of the bulk PV effect
We describe the tensor representation of J arising from the bulk PV effect in the BT system. The tetragonal phase of BT with 4 mm point group symmetry has the bulk PV tensor with three independent nonzero components under the irradiation of linearly polarized light. We define the incident direction of light (// ) as i = 1 and the polar axis (//[001]) as i = 3. Using the polarization unit vector [e = (e_{1}, e_{2}, e_{3})], the three nonzero components of the bulk PV tensor (β_{31}, β_{33} and β_{15}) and , the photocurrent density vector [J = (J_{1}, J_{2}, J_{3})] can be written as follows:
Taking into account that the bulk PV tensor (β_{ijk}) is a thirdrank tensor and is symmetric for the latter two indices (j and k), we adopt here the standard 3 × 6 matrix notation: with , as used in the representation of the piezoelectric tensor.
Additional Information
How to cite this article: Inoue, R. et al. Giant photovoltaic effect of ferroelectric domain walls in perovskite single crystals. Sci. Rep. 5, 14741; doi: 10.1038/srep14741 (2015).
References
Chynoweth, A. G. Surface spacecharge layers in barium titanate. Phys. Rev. 102, 705–714 (1956).
Koch, W. T. H., Munser, R., Ruppel, W. & Würfel, P. Bulk photovoltaic effect in BaTiO3 . Solid State Commun. 17, 847–850 (1975).
Koch, W. T. H., Munser, R., Ruppel, W. & Würfel, P. Anomalous photovoltage in BaTiO3 . Ferroelectrics 13, 305–307 (1976).
Chen, F. S. Optically induced change of refractive indices in LiNbO 3 and LiTaO3 . J. Appl. Phys. 40, 3389–3396 (1969).
Perterson, G. E., Glass, A. M. & Negran, T. J. Control of the susceptibility of lithium niobate to laserinduced refcactive index changes. Appl. Phys. Lett. 19, 130–132 (1971).
Glass, A. M., von der Linde, D. & Negran, T. J. Highvoltage bulk photovoltaic effect and the photorefractive process in LiNbO3 . Appl. Phys. Lett. 25, 233–235 (1974).
Krumins, A. E. & Günter P. Photogalvanic effect and photoconductivity in reduced potassium niobate crystals. Phys. Stat. Sol. A 55, K185–K189 (1979).
Krätzig, E. & Orlowski, R. LiTaO3 as holographic storage material. Appl. Phys. 15, 133–139 (1978).
Astafiev, S. B., Fridkin, V. M. & Lazarev, V. G. The influence of the magnetic field on the linear bulk photovoltaic current in piezoelectric semiconductor GaP. Ferroelectrics 80, 251–254 (1988).
Fridkin, V. M. et al. The experimental investigation of the photovoltaic effect in some crystals without a center of symmetry. Appl. Phys. 25, 77–80 (1981).
Sasabe, H., Nakayama, T., Kumazawa, K., Miyata, S. & Fukada, E. Photovoltaic effect in Poly (vinylidene fluoride). Polymer J 13, 967–973 (1981).
Inoue, R. et al. Photocurrent characteristics of Mndoped barium titanate ferroelectric single crystals. Jpn. J. Appl. Phys. 52, 09KF03 (2013).
Yang, S. Y. et al. Abovebandgap voltages from ferroelectric photovoltaic devices. Nat. Nanotechnol. 5, 143–147 (2010).
Seidel, J. et al. Efficient photovoltaic current generation at ferroelectric domain walls. Phys. Rev. Lett. 107, 126805 (2011).
Bhatnagar, A. et al. Role of domain walls in the abnormal photovoltaic effect in BiFeO3 . Nat. Commun. 4, 2835 (2013).
Young, S. M. & Rappe, A. M. First principle calculation of the shift current photovoltaic effect in ferroelectrics. Phys. Rev. Lett. 109, 116601 (2012).
Shirmer, O. F., Imlau, M. & Merschjann, C. Bulk photovoltaic effect of LiNbO3:Fe and its smallpolaronbased microscopic interpretation. Phys. Rev. B 83, 165106 (2011).
Sturman, B. I. & Fridkin, V. M. The Photovoltaic and Photorefractive Effects in Noncentrosymmetric Materials (Gordon and Breach Science, 1992).
Meyer, B. & Vanderbilt, D. ab initio study of ferroelectric domain walls in PbTiO3 . Phys. Rev. B 65, 104111 (2002).
Zhang, Q. & Goddard III, W. A. Charge and polarization distributions at the 90° domain wall in barium titanate ferroelectric. Appl. Phys. Lett. 89, 182903 (2006).
Lubk, A., Gemming, S. & Spaldin, N. A. Firstprinciples study of ferroelectric domain walls in multiferroic bismurh ferrite. Phys. Rev. B 80, 104110 (2009).
Hlinka, J., Márton, P. Phenomenological model of a 90° domain wall in BaTiO3type ferroelectrics. Phys. Rev. B 74, 104104 (2006).
Catalan, G., Seidel, J., Ramesh, R. & Scott, J. F. Domain wall nanoelectronics. Rev. Mod. Phys. 84, 119–156 (2012).
Pramanick, A., Prewitt, A. D., Forrester, J. S. & Jones, J. L. Domains, domain walls and defects in perovskite ferroelectric oxides: a review of present understanding and recent contributions. Crit. Rev. Solid State Mater. Sci. 37, 243–275 (2012).
Little, E. A. Dynamic behavior of domain walls in barium titanate. Phys. Rev. 98, 978–984 (1955).
Tanaka, M. & Honjo G. Electron optical studies of barium titanate single crystal films. J. Phys. Soc. Jpn. 19, 954–970 (1964).
Dennis, M. D. & Bradt R. C. Thickness of 90° ferroelectric domain walls in (Ba,Pb)TiO3 single crystals. J. Appl. Phys. 45, 1931–1933 (1974).
Tsai, F., Khiznichenko, V. & Cowley J. M. Highresolution electromicroscopy of 90° ferroelectric domain boundaries in BaTiO3 and Pb(Zr0.52Ti0.48)O3 . Ultramicroscopy 45, 55–63 (1992).
Zhang, X., Hashimoto, T. & Joy D. C. Electron holographyc study of ferroelectric domain walls. Appl. Phys. Lett. 60, 784–786 (1992).
Floquet, N. & Valot C. Ferroelectric domain walls in BaTiO 3 : structural wall model interpreting fingerprints in XRPD daiagrams. Ferroelectrics 234, 107–122 (1999).
Würfel, P. Physics of Solar Cells (Willey, Weinheim, 2009).
Acknowledgements
This research is partly granted by the Japan Society for the Promotion of Science (JSPS) through the Funding Program for Next Generation WorldLeading Researchers (NEXT Program), initiated by the Council for Science and Technology Policy (CSTP).
Author information
Authors and Affiliations
Contributions
R. Inoue and Y.N. conceived and designed the experiments. S.I. and R. Imura contributed material and Y.K. and T.O. carried out PFM investigations. R. Inoue performed the experiments and the analysis. R. Inoue, Y.N. and M.M. cowrote the paper.
Ethics declarations
Competing interests
The authors declare no competing financial interests.
Electronic supplementary material
Rights and permissions
This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
About this article
Cite this article
Inoue, R., Ishikawa, S., Imura, R. et al. Giant photovoltaic effect of ferroelectric domain walls in perovskite single crystals. Sci Rep 5, 14741 (2015). https://doi.org/10.1038/srep14741
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/srep14741
This article is cited by

Memristive Artificial Synapses for Neuromorphic Computing
NanoMicro Letters (2021)

Successive redoxmediated visiblelight ferrophotovoltaics
Nature Communications (2020)

Giant photovoltaic response in band engineered ferroelectric perovskite
Scientific Reports (2018)

Dependence of dielectric and photovoltaic properties of Pt/PLZT/LNO on the temperature and La doping content
Journal of SolGel Science and Technology (2018)

Gapstate engineering of visiblelightactive ferroelectrics for photovoltaic applications
Nature Communications (2017)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.