Polarization controlled photovoltaic and self-powered photodetector characteristics in Pb-free ferroelectric thin film
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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TL;DR: The application of ferroelectric materials (i.e. solids that exhibit spontaneous electric polarisation) in solar cells has a long and controversial history as mentioned in this paper, and the recent successful application of inorganic and hybrid perovskite structured materials (e.g. BiFeO3, CsSnI3, CH3NH3PbI3) emphasises that polar semiconductors can be used in conventional photovoltaic architectures.
Abstract: The application of ferroelectric materials (i.e. solids that exhibit spontaneous electric polarisation) in solar cells has a long and controversial history. This includes the first observations of the anomalous photovoltaic effect (APE) and the bulk photovoltaic effect (BPE). The recent successful application of inorganic and hybrid perovskite structured materials (e.g. BiFeO3, CsSnI3, CH3NH3PbI3) in solar cells emphasises that polar semiconductors can be used in conventional photovoltaic architectures. We review developments in this field, with a particular emphasis on the materials known to display the APE/BPE (e.g. ZnS, CdTe, SbSI), and the theoretical explanation. Critical analysis is complemented with first-principles calculation of the underlying electronic structure. In addition to discussing the implications of a ferroelectric absorber layer, and the solid state theory of polarisation (Berry phase analysis), design principles and opportunities for high-efficiency ferroelectric photovoltaics are presented.
248 citations
Journal Article•
TL;DR: In this paper, an efficient and low-cost method to achieve high-performance "visible-blind" microscale ZnS nanobelt-based ultraviolet (UV)-light sensors without using a lithography technique, by increasing the surface areas exposed to light, is reported.
Abstract: Although there has been significant progress in the fabrication and performance optimization of one-dimensional nanostructure-based photodetectors, it is still a challenge to develop an effective and low-cost device with high performance characteristics, such as a high photocurrent/ dark-current ratio, photocurrent stability, and fast time response. Herein an efficient and low-cost method to achieve high-performance 'visible-blind' microscale ZnS nanobelt-based ultraviolet (UV)-light sensors without using a lithography technique, by increasing the nanobelt surface areas exposed to light, is reported. The devices exhibit about 750 times enhancement of a photocurrent compared with individual nanobelt-based sensors and an ultrafast time response. The photocurrent stability and time response to UV-light do not change significantly when a channel distance is altered from 2 to 100 μm or the sensor environment changes from air to vacuum and different measurement temperatures (60 and 150°C). The photoelectrical behaviors can be recovered well after returning the measurement conditions to air and room temperature again. The low cost and high performance of the resultant ZnS nanobelt photodetectors guarantee their highest potential for visible-blind UV-light sensors working in the UV-A band.
204 citations
73 citations
TL;DR: The fabrication of self-powered, carbon dot (CD) enhanced, flexible ZnO/graphite heterojunction based UV detector, where cellulose paper has been used as the substrate with Schottky characteristics is reported.
Abstract: The fabrication of flexible as well as self-powered optoelectronic devices is a growing and challenging area of research Some scientists have reported the fabrication of either flexible or self-powered photodetectors recently However, most of the literature studies fail to report the fabrication of self-powered as well as flexible photodetectors This study reports the fabrication of self-powered, carbon dot (CD)-enhanced, flexible ZnO/graphite heterojunction-based UV detector where cellulose paper has been used as the substrate A detailed study on the crystallinity and the defects of the ZnO nanorods has been done with appropriate characterizations The CD-enhanced ZnO/graphite heterojunction showed Schottky characteristics The Schottky parameters such as the barrier height, ideality factor, and the series resistance have also been calculated using the Cheung-Cheung method The observed values of barrier height, ideality factor, and the series resistance are 074 eV, 374, and 503 kΩ, respectively The transient response at self-powered condition has been demonstrated The response time and the recovery time at self-powered condition have also been calculated with the help of the transient response, and those values are ∼2 and ∼32 s, respectively The responsivity and the specific detectivity of the fabricated UV detector have been calculated as 957 mA/W and 427×108 Jones, respectively, at 330 nm wavelength, which is quite comparable with literature-reported values, considering a self-powered photodetector
36 citations
TL;DR: In this article, a polycrystalline BiFeO3 (BFO) thin film on a transparent substrate also has the ferroelectric switchable diode and photovoltaic effects.
28 citations
References
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TL;DR: In this paper, the Shockley-Queisser limit for solar cells was overcome in the ferroelectric insulator BaTiO3, which is the same insulator used in this paper.
Abstract: The Shockley–Queisser limit for solar cells is overcome in the ferroelectric insulator BaTiO3.
320 citations
TL;DR: An up-to-date review on the coupling of polarization with optical properties in ferroelectrics, highlighting several important issues and parameters, such as the role of domain walls, ways to tune the bandgap, consequences arising from the polarization switchability, and the roles of defects and contact electrodes, as well as the downscaling effects.
Abstract: Ferroelectrics carry a switchable spontaneous electric polarization. This polarization is usually coupled to strain, making ferroelectrics good piezoelectrics. When coupled to magnetism, they become so-called multiferroic systems, a field that has been widely investigated since 2003. While ferroelectrics are birefringent and non-linear optically transparent materials, the coupling of polarization with optical properties has received, since 2009, renewed attention, triggered notably by low-bandgap ferroelectrics suitable for sunlight spectrum absorption and original photovoltaic effects. Consequently, power conversion efficiencies up to 8.1% were recently achieved and values of 19.5% were predicted, making photoferroelectrics promising photovoltaic alternatives. This article aims at providing an up-to-date review on this emerging and rapidly progressing field by highlighting several important issues and parameters, such as the role of domain walls, ways to tune the bandgap, consequences arising from the polarization switchability, and the role of defects and contact electrodes, as well as the downscaling effects. Beyond photovoltaicity, other polarization-related processes are also described, like light-induced deformation (photostriction) or light-assisted chemical reaction (photostriction). It is hoped that this overview will encourage further avenues to be explored and challenged and, as a byproduct, will inspire other research communities in material science, e.g., so-called hybrid halide perovskites.
306 citations
TL;DR: In this paper, the time-dependent polarization relaxation behavior induced by a depolarization field E(d) was investigated on high-quality ultrathin BaTiO3/SrRuO3 capacitors.
Abstract: Time-dependent polarization relaxation behavior induced by a depolarization field E(d) was investigated on high-quality ultrathin SrRuO3/BaTiO3/SrRuO3 capacitors. The E(d) values were determined experimentally from an applied external field to stop the net polarization relaxation. These values agree with those from the electrostatic calculations, demonstrating that a large E(d) inside the ultrathin ferroelectric layer could cause severe polarization relaxation. For numerous ferroelectric devices of capacitor configuration, this effect will set a stricter size limit than the critical thickness issue.
298 citations
TL;DR: The application of ferroelectric materials (i.e. solids that exhibit spontaneous electric polarisation) in solar cells has a long and controversial history as mentioned in this paper, and the recent successful application of inorganic and hybrid perovskite structured materials (e.g. BiFeO3, CsSnI3, CH3NH3PbI3) emphasises that polar semiconductors can be used in conventional photovoltaic architectures.
Abstract: The application of ferroelectric materials (i.e. solids that exhibit spontaneous electric polarisation) in solar cells has a long and controversial history. This includes the first observations of the anomalous photovoltaic effect (APE) and the bulk photovoltaic effect (BPE). The recent successful application of inorganic and hybrid perovskite structured materials (e.g. BiFeO3, CsSnI3, CH3NH3PbI3) in solar cells emphasises that polar semiconductors can be used in conventional photovoltaic architectures. We review developments in this field, with a particular emphasis on the materials known to display the APE/BPE (e.g. ZnS, CdTe, SbSI), and the theoretical explanation. Critical analysis is complemented with first-principles calculation of the underlying electronic structure. In addition to discussing the implications of a ferroelectric absorber layer, and the solid state theory of polarisation (Berry phase analysis), design principles and opportunities for high-efficiency ferroelectric photovoltaics are presented.
296 citations
TL;DR: In this article, the authors investigated a switchable ferroelectric diode effect and its physical mechanism in Pt/BiFeO{}_{3}$/SrRuO${}{3}µ thin-film capacitors and showed that a defective layer (possibly an oxygen-vacancyrich layer) becomes formed and disturbs carrier injection.
Abstract: We investigated a switchable ferroelectric diode effect and its physical mechanism in Pt/BiFeO${}_{3}$/SrRuO${}_{3}$ thin-film capacitors. Our results of electrical measurements support that, near the Pt/BiFeO${}_{3}$ interface of as-grown samples, a defective layer (possibly an oxygen-vacancy-rich layer) becomes formed and disturbs carrier injection. We therefore used an electrical training process to obtain ferroelectric control of the diode polarity where, by changing the polarization direction using an external bias, we could switch the transport characteristics between forward and reverse diodes. Our system is characterized with a rectangular polarization-hysteresis loop with which we confirmed that the diode-polarity switching occurred at the ferroelectric coercive voltage. Moreover, we observed a simultaneous switching of the diode polarity and the associated photovoltaic response dependent on the ferroelectric domain configurations. Our detailed study suggests that the polarization charge can affect the Schottky barrier at the ferroelectric/metal interfaces, resulting in a modulation of the interfacial carrier injection. The amount of polarization-modulated carrier injection can affect the transition voltage value at which a space-charge-limited bulk current--voltage ($J$--$V$) behavior is changed from Ohmic (i.e., $J$ \ensuremath{\propto} $V$) to nonlinear (i.e., $J$ \ensuremath{\propto} ${V}^{n}$ with $n$ \ensuremath{\ge} 2). This combination of bulk conduction and polarization-modulated carrier injection explains the detailed physical mechanism underlying the switchable diode effect in ferroelectric capacitors.
277 citations