Enlarging photovoltaic effect: combination of classic photoelectric and ferroelectric photovoltaic effects.
Ontology highlight
ABSTRACT:
SUBMITTER: Zhang J
PROVIDER: S-EPMC3696897 | biostudies-other | 2013
REPOSITORIES: biostudies-other
Similar Datasets
Project description:A ferroelectric-photovoltaic effect in nanowires of antimony sulfoiodide (SbSI) is presented for the first time. Sonochemically prepared SbSI nanowires have been characterized using high-resolution transmission electron microscopy (HRTEM) and optical diffuse reflection spectroscopy (DRS). The temperature dependences of electrical properties of the fabricated SbSI nanowires have been investigated too. The indirect forbidden energy gap EgIf = 1.862 (1) eV and Curie temperature TC = 291 (2) K of SbSI nanowires have been determined. Aligned SbSI nanowires have been deposited in an electric field between Pt electrodes on alumina substrate. The photoelectrical response of such a prepared ferroelectric-photovoltaic (FE-PV) device can be switched using a poling electric field and depends on light intensity. The photovoltage, generated under ? = 488 nm illumination of Popt = 127 mW/cm² optical power density, has reached UOC = 0.119 (2) V. The presented SbSI FE-PV device is promising for solar energy harvesting as well as for application in non-volatile memories based on the photovoltaic effect.
| S-EPMC6523164 | biostudies-literature
Project description:Ferroelectric materials for photovoltaics have sparked great interest because of their switchable photoelectric responses and above-bandgap photovoltages that violate conventional photovoltaic theory. However, their relatively low photocurrent and power conversion efficiency limit their potential application in solar cells. To improve performance, conventional strategies focus mainly on narrowing the bandgap to better match the solar spectrum, leaving the fundamental connection between polar order and photovoltaic effect largely overlooked. We report large photovoltaic enhancement by A-site substitutions in a model ferroelectric photovoltaic material, BiFeO3. As revealed by optical measurements and supported by theoretical calculations, the enhancement is accompanied by the chemically driven rotational instability of the polarization, which, in turn, affects the charge transfer at the band edges and drives a direct-to-indirect bandgap transition, highlighting the strong coupling between polarization, lattice, and orbital order parameters in ferroelectrics. Polar order engineering thus provides an additional degree of freedom to further boost photovoltaic efficiency in ferroelectrics and related materials.
| S-EPMC6035034 | biostudies-literature
Project description:The quest for a solid state universal memory with high-storage density, high read/write speed, random access and non-volatility has triggered intense research into new materials and novel device architectures. Though the non-volatile memory market is dominated by flash memory now, it has very low operation speed with ~10??s programming and ~10?ms erasing time. Furthermore, it can only withstand ~10(5) rewriting cycles, which prevents it from becoming the universal memory. Here we demonstrate that the significant photovoltaic effect of a ferroelectric material, such as BiFeO3 with a band gap in the visible range, can be used to sense the polarization direction non-destructively in a ferroelectric memory. A prototype 16-cell memory based on the cross-bar architecture has been prepared and tested, demonstrating the feasibility of this technique.
| S-EPMC3709492 | biostudies-literature
Project description:Shift current is a steady-state photocurrent generated in non-centrosymmetric single crystals and has been considered to be one of the major origins of the bulk photovoltaic effect. The mechanism of this effect is the transfer of photogenerated charges by the shift of the wave functions, and its amplitude is closely related to the polarization of the electronic origin. Here, we report the photovoltaic effect in an organic molecular crystal tetrathiafulvalene-p-chloranil with a large ferroelectric polarization mostly induced by the intermolecular charge transfer. We observe a fairly large zero-bias photocurrent with visible-light irradiation and switching of the current direction by the reversal of the polarization. Furthermore, we reveal that the travel distance of photocarriers exceeds 200??m. These results unveil distinct features of the shift current and the potential application of ferroelectric organic molecular compounds for novel optoelectric devices.The bulk photovoltaics refers to an effect whereby electrons move directionally in non-centrosymmetric crystals upon light radiation. Here, Nakamura et al. observe this effect in a ferroelectric organic charge-transfer complex, which shows large diffusion distance of photogenerated electrons over 200?µm.
| S-EPMC5561111 | biostudies-literature
Project description:Tuning the bandgap in ferroelectric complex oxides is a possible route for improving the photovoltaic activity of materials. Here, we report the realization of this effect in epitaxial thin films of the ferroelectric complex oxide Bi3.25La0.75Ti3O12 (BLT) suitably doped by Fe and Co. Our study shows that Co (BLCT) doping and combined Fe, Co (BLFCT) doping lead to a reduction of the bandgap by more than 1?eV compared to undoped BLT, accompanied by a surprisingly more efficient visible light absorption. Both BLCT and BLFCT films can absorb visible light with a wavelength of up to 500?nm while still exhibiting ferroelectricity, whereas undoped BLT only absorbs UV light with a wavelength of less than 350?nm. Correlated with its bandgap reduction, the BLFCT film shows a photocurrent density enhanced by 25 times compared to that of BLT films. Density functional theory calculations indicate that the bandgap contraction is caused by the formation of new energy states below the conduction bands due to intermixed transition metal dopants (Fe, Co) in BLT. This mechanism of tuning the bandgap by simple doping can be applied to other wide-bandgap complex oxides, thereby enabling their use in solar energy conversion or optoelectronic applications.
| S-EPMC4911611 | biostudies-literature
Project description:Spin and valley degrees of freedom in materials without inversion symmetry promise previously unknown device functionalities, such as spin-valleytronics. Control of material symmetry with electric fields (ferroelectricity), while breaking additional symmetries, including mirror symmetry, could yield phenomena where chirality, spin, valley, and crystal potential are strongly coupled. Here we report the synthesis of a halide perovskite semiconductor that is simultaneously photoferroelectricity switchable and chiral. Spectroscopic and structural analysis, and first-principles calculations, determine the material to be a previously unknown low-dimensional hybrid perovskite (R)-(-)-1-cyclohexylethylammonium/(S)-(+)-1 cyclohexylethylammonium) PbI3. Optical and electrical measurements characterize its semiconducting, ferroelectric, switchable pyroelectricity and switchable photoferroelectric properties. Temperature dependent structural, dielectric and transport measurements reveal a ferroelectric-paraelectric phase transition. Circular dichroism spectroscopy confirms its chirality. The development of a material with such a combination of these properties will facilitate the exploration of phenomena such as electric field and chiral enantiomer-dependent Rashba-Dresselhaus splitting and circular photogalvanic effects.
| S-EPMC7048427 | biostudies-literature
Project description:The photovoltaic (PV) effect in polar materials offers great potential for light-energy conversion that generates a voltage beyond the bandgap limit of present semiconductor-based 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 DW-PV 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 DW-PV 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 thin-film form.
| S-EPMC4595799 | biostudies-other
Project description:Recently the solar energy, an inevitable part of green energy source, has become a mandatory topics in frontier research areas. In this respect, non-centrosymmetric ferroelectric perovskites with open circuit voltage (VOC) higher than the bandgap, gain tremendous importance as next generation photovoltaic materials. Here a non-toxic co-doped Ba1-x(Bi0.5Li0.5) x TiO3 ferroelectric system is designed where the dopants influence the band topology in order to enhance the photovoltaic effect. In particular, at the optimal doping concentration (x opt ?~?0.125) the sample reveals a remarkably high photogenerated field EOC?=?320?V/cm (VOC?=?16?V), highest ever reported in any bulk polycrystalline non-centrosymmetric systems. The band structure, examined through DFT calculations, suggests that the shift current mechanism is key to explain the large enhancement in photovoltaic effect in this family.
| S-EPMC5964148 | biostudies-literature
Project description:Recently, ferroelectric perovskite oxides have drawn much attention due to potential applications in the field of solar energy conversion. However, the power conversion efficiency of ferroelectric photovoltaic effect currently reported is far below the expectable value. One of the crucial problems lies in the two back-to-back Schottky barriers, which are formed at the ferroelectric-electrode interfaces and blocking most of photo-generated carriers to reach the outside circuit. Herein, we develop a new approach to enhance the ferroelectric photovoltaic effect by introducing the polarization-dependent interfacial coupling effect. Through inserting a semiconductor ZnO layer with spontaneous polarization into the ferroelectric ITO/PZT/Au film, a p-n junction with strong polarization-dependent interfacial coupling effect is formed. The power conversion efficiency of the heterostructure is improved by nearly two orders of magnitude and the polarization modulation ratio is increased about four times. It is demonstrated that the polarization-dependent interfacial coupling effect can give rise to a great change in band structure of the heterostructure, not only producing an aligned internal electric field but also tuning both depletion layer width and potential barrier height at PZT-ZnO interface. This work provides an efficient way in developing highly efficient ferroelectric-based solar cells and novel optoelectronic memory devices.
| S-EPMC4782167 | biostudies-other
Project description:Ferroelectric synapses using polarization switching (a purely electronic switching process) to induce analog conductance change have attracted considerable interest. Here, we propose ferroelectric photovoltaic (FePV) synapses that use polarization-controlled photocurrent as the readout and thus have no limitations on the forms and thicknesses of the constituent ferroelectric and electrode materials. This not only makes FePV synapses easy to fabricate but also reduces the depolarization effect and hence enhances the polarization controllability. As a proof-of-concept implementation, a Pt/Pb(Zr0.2Ti0.8)O3/LaNiO3 FePV synapse is facilely grown on a silicon substrate, which demonstrates continuous photovoltaic response modulation with good controllability (small nonlinearity and write noise) enabled by gradual polarization switching. Using photovoltaic response as synaptic weight, this device exhibits versatile synaptic functions including long-term potentiation/depression and spike-timing-dependent plasticity. A simulated FePV synapse-based neural network achieves high accuracies (>93%) for image recognition. This study paves a new way toward highly controllable and silicon-compatible synapses for neuromorphic computing.
| S-EPMC7736912 | biostudies-literature