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 article, the electrocaloric effect in lead-free Zr doped Ba08Ca02(ZrxTi1−x)O3 (BCTZ) ceramics was investigated.
Abstract: The electrocaloric effect was investigated in lead-free Zr doped Ba08Ca02(ZrxTi1−x)O3 (BCTZ) ceramics synthesized by a conventional sintering process Room-temperature x-ray diffraction analysis showed that the tetragonal structure is obtained in BCTZ for x ≤ 008 and a pseudo cubic phase for x > 008 The dielectric spectroscopy and calorimetry revealed that the Curie temperature decreases as a consequence of Zr doping and that the BCTZ exhibits a first order ferroelectric phase transition The electrocaloric effect was determined by the calculation of the electrocaloric change of temperature (ΔT) using the Maxwell relation based on the P–E hysteresis loops measured at different temperatures A large electrocaloric responsivity ΔT/ΔE = 034 × 10−6 Km/V was found for x = 004, which significantly exceeds of values found so far in other lead-free electrocaloric materials
129 citations
TL;DR: It is well known that the photovoltage in semiconductors, whatever its nature, cannot exceed the energy gap, which is several volts as discussed by the authors, for an infinitely large intensity of the exciting light.
Abstract: It is well known that the photovoltage in semiconductors, whatever its nature, cannot exceed the energy gap, which is several volts. For instance, in a homogeneous semiconductor the Dember (diffusion) photovoltage does not exceed the following value [3.6] for an infinitely large intensity of the exciting light:
$$ V = \frac{{kT}}{q}\ell n\frac{{{n_1}}}{{{n_0}}} < < \frac{{kT}}{q}\ell n\frac{{{N_c}}}{{{n_0}}} = {E_g}.$$
(6.1)
124 citations
TL;DR: A novel nanostructured ferroelectric photovoltaic material, consisting of the ferro electric lead zirconate titanate (PZT) film and Ag(2) O semiconductor nanoparticles of comparatively narrow bandgap, has demonstrated a remarkable enhancement in the photvoltaic effects and the highest light-electricity conversion efficiency among those PZT-based photodiodes previously reported.
Abstract: A novel nanostructured ferroelectric photovoltaic material, consisting of the ferroelectric lead zirconate titanate (PZT) film and Ag(2) O semiconductor nanoparticles of comparatively narrow bandgap, has demonstrated a remarkable enhancement in the photovoltaic effects and the highest light-electricity conversion efficiency among those PZT-based photodiodes previously reported. This work sheds light on the design and enhanced performance of new optoelectronic and solar energy devices.
106 citations
TL;DR: This study clarifies the role of the temperature effect and the thermo-phototronic effect in the photovoltaic process of the BFO material and provides a feasible route for pushing forward practical applications of self-powered UV photodetectors.
Abstract: Ferroelectric materials can be utilized for fabricating photodetectors because of the photovoltaic effect. Enhancing the photovoltaic performance of ferroelectric materials is still a challenge. Here, a self-powered ultraviolet (UV) photodetector is designed based on the ferroelectric BiFeO3 (BFO) material, exhibiting a high current/voltage response to 365 nm light in heating/cooling states. The photovoltaic performance of the BFO-based device can be well modulated by applying different temperature variations, where the output current and voltage can be enhanced by 60 and 75% in heating and cooling states, respectively. The enhancement mechanism of the photocurrent is associated with both temperature effect and thermo-phototronic effect in the photovoltaic process. Moreover, a 4 × 4 matrix photodetector array has been designed for detecting the 365 nm light distribution in the cooling state by utilizing photovoltage signals. This study clarifies the role of the temperature effect and the thermo-phototroni...
103 citations
TL;DR: In this paper, a physical model of the effect of light polarized parallel and perpendicular to the c-axis on short-circuit photocurrents with opposite signs is presented. But the model is restricted to BaTiO3 single crystals.
Abstract: In ferroelectric melt-grown BaTiO3 single crystals steady-state short-circuit photocurrents have been observed parallel to the c-axis. At room temperature light polarized parallel and perpendicular to the c-axis produces short-circuit photocurrents with opposite sign. Along with the temperature dependence a physical model of this effect is outlined.
84 citations