Composition gradient (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 film with improved dielectric,piezoelectric and ferroelectric temperature stability

Lead-free (1-x)Ba(Ti_0.8Zr_0.2)O₃-x(Ba_0.7Ca_0.3)TiO₃ (BZT-BCT) possesses comparable piezoelectric constant with lead zirconate titanate (PZT), but its poor temperature electric performances stability and low Curie temperature limit its application. Here we designed composition graded BZT-BCT films with improved temperature stability of piezoelectric, ferroelectric, and dielectric performances over a wide temperature range, and the d₃₃ reaches 21 pm/V with hysteresis loop even at 180 °C, which is far above the Curie temperature of BZT-BCT ceramic and BZT-0.5BCT film. The excellent temperature stability is ascribed to the lattice distortion and strain gradient in the grains caused by ions diffusion, and could suppress phase transition. This work could bring forward a feasible design for dielectric/piezoelectric/ferroelectric devices operating in harsh temperature environment.     

Phenomenological modeling of phase transitions and electrocaloric effect in Ba(Zr0.2Ti0.8)O3-(Ba0.7Ca0.3)TiO3

Ba(Zr_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃ (BZT-xBCT) is a promising lead-free ferroelectric system. In this paper, we present two sets of free energy coefficients and carry out phenomenological modeling to study the phase transition and electrocaloric effect. The calculated phase diagram is in excellent quantitative agreement with experiments. Furthermore, we propose a new method based on effective internal electric field to simulate polarization in the macroscopic paraelectric state of ferroelectric relaxor. The computed composition and temperature-dependent entropy and temperature change induced by electrocaloric effect are in good agreement with the measured data available for single crystal.     

Piezoelectric properties of (1-x)BZT-xBCT system for energy harvesting applications

In this study, we investigated (1-x)Ba(Zr_0.2Ti_0.8)O₃–x(Ba_0.7Ca_0.3)TiO₃ lead-free piezoelectric ceramics for energy harvester applications. The (1-x)BZT-xBCT ceramic is a promising lead-free piezoelectric material in the field of piezoelectric energy harvesting. Piezoelectric and energy properties of (1-x)BZT-xBCT ceramics were analyzed to confirm the possibility of using them as energy-harvesting materials. Especially, the vicinity of the phase convergence region was investigated to improve their piezoelectric properties. In the phase convergence region, cubic, rhombohedral, orthorhombic, and tetragonal regions co-exist within the narrow region. Near the phase transition region between the orthorhombic and tetragonal phase, the highest piezoelectric property d₃₃?=?464 pC/N and the highest energy density of 158.5 μJ/cm³ were observed. This output energy density of 158.5 μJ/cm³ is the recorded highest value among lead-free ceramics. We found that the optimal sintering temperature was 1475?°C and the optimal composition was BZT-0.5BCT.     

The electrical properties of (Ba,Ca, Ce,Ti, Zr)O3 thermistor for wide-temperature sensor architecture

A series of new negative temperature coefficient (NTC) thermal materials based on (Ba_0.85Ca_0.15)_1-xCe_x/2(Zr_0.1Ti_0.9)O₃ (0.00 ≤ x ≤ 0.20) ceramics were synthesized by a solid-state method. X-ray diffraction, scanning electron microscope and X-ray photoelectron spectroscopy were used to demonstrate the crystal structure, morphology, and composition of the (Ba_0.85Ca_0.15)_1-xCe_x/2(Zr_0.1Ti_0.9)O₃ ceramics, which were composed of solid solution based on the BaTiO₃ phase. The average grain size of doped ceramic samples experienced the process of first decreasing and then increasing. The doping of Ce has reduced the sintering temperature. The temperature-dependent resistance analysis revealed that with the change of doping amount x, the thermal constant B_300/1200 (1.21 × 10⁴–1.13 × 10⁴ K) and the activation energy E_a300/1200 (0.9777–1.0471eV) was initially increased to maximum values at x = 0.05, followed by the decreasing when x > 0.05. It has been established that the concentration of oxygen vacancies is affected by the transition between Ce⁴⁺ and Ce³⁺ provided by high levels of Ce doping. (Ba_0.85Ca_0.15)_1-xCe_x/2(Zr_0.1Ti_0.9)O₃ ceramics exhibited excellent negative temperature characteristics in the range of 300–1200 °C. Moreover, the temperature resistance linearity was improved after samples were aged. Hence, the (Ba_0.85Ca_0.15)_1-xCe_x/2(Zr_0.1Ti_0.9)O₃ ceramics were regarded as a promising material for high-temperature NTC thermistors in a wide temperature range.     

Ferroelectric,dielectric, and impedance properties of Sm-modified Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 ceramics

To investigate the effect of Sm doping on the electrical properties of Ba(Zr_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃ (BZT-xBCT) (x = 40, 50, 60) ceramics, three Sm-modified ceramics were prepared using the conventional solid-state reaction method. Related electrical measurements, including ferroelectric and dielectric investigations and impedance spectroscopy, were recorded for these ceramics. It was found that a tilted morphotropic phase boundary resulted from the addition of Sm, which induced the best piezoelectric properties and insulating behaviour in the Sm-BZT-60BCT sample. An abnormal P-E loop shrinkage appeared in the Sm-BZT-50BCT sample but not in the other two samples. This could be attributable to the different electronegativities between Ca²⁺ and Ba²⁺ and between Zr⁴⁺ and Ti⁴⁺, whose contents are different in varied samples and have an effect on defect-dipole alignment as well as spontaneous polarization. The activation energies for the bulk conductivity in the three composites were calculated to be 0.28 ± 0.01, 0.08 ± 0.01, and 0.36 ± 0.01 eV, confirming the existence of oxygen vacancies in our samples. The Sm dopant is responsible for the oxygen vacancies. This also leads to an increased Curie temperature in the three composites.     

Influence of composition on the unipolar electric fatigue of Ba(Zr0.2Ti0.8)O3‐(Ba0.7Ca0.3)TiO3 lead‐free piezoceramics

The lead‐free (1?x)Ba(Zr_0.2Ti_0.8)O₃‐x(Ba_0.7Ca_0.3)TiO₃ system is considered as promising candidate for the replacement of lead‐based piezoceramics in actuation applications, during which electric fatigue is a major concern. This issue was addressed in this work, where the unipolar fatigue resistance of three (1?x)Ba(Zr_0.2Ti_0.8)O₃‐x(Ba_0.7Ca_0.3)TiO₃ compositions with different crystallographic structures (rhombohedral, orthorhombic, and tetragonal) was evaluated. Strain asymmetry and development of an internal bias field were observed in all compositions. The decrease in the remanent polarization and the large signal piezoelectric coefficient after 10⁷ unipolar cycles was found to lie between 6%‐12% and 2%‐13%, respectively. The most pronounced fatigue was observed for the orthorhombic composition, which has the largest extrinsic contribution to strain. On the other hand, the best fatigue resistance was observed for the tetragonal composition, which has a predominantly intrinsic strain response. The correlation of fatigue resistance with strain mechanism was corroborated with determination of the Rayleigh parameters and changes in the domain morphology after cycling as confirmed by piezoresponse force microscopy.     

Electrocaloric Effect in Ba(Zr,Ti)O3–(Ba,Ca)TiO3 Ceramics Measured Directly

In this paper, we report on studies of the electrocaloric (EC) effect in lead‐free (1?x)Ba(Zr_0.2Ti_0.8)O₃–x(Ba_0.7Ca_0.3)TiO₃ ceramics with compositions range between 0.32 ≤ x ≤ 0.45. The EC effect was measured directly using a modified differential scanning calorimeter. The maximum EC temperature change, ΔT_direct = 0.33 K under an electric field of 2 kV/mm, was observed for the composition with x = 0.32 at ~63°C. We found that the EC effect peaks not only around the Curie temperature but also at the transition between the ferroelectric phases with different symmetries. A strong discrepancy observed between the results of the direct measurements and indirect estimations points out that using Maxwell's equations is invalid for the thermodynamic nonequilibrium conditions that accompany only partial (incomplete) poling of ceramics. We also observe a nonlinearity of the EC effect above the Curie temperature and in the temperature range corresponding to the tetragonal ferroelectric phase.     

Microscopic origin of the enhanced piezoelectric thermal stability in acceptor doped lead-free Ba(Ti0.8Zr0.2)O3-50(Ba0.7Ca0.3)TiO3 ceramic

Acceptor doping is effective in enhancing thermal stability in piezoceramics, while the reason underlying is still unclear and awaits explanation. In this work, through doping acceptor Mn in lead-free Ba(Ti_0.8Zr_0.2)O₃-50(Ba_0.7Ca_0.3)TiO₃ ceramic, our results show that doping Mn achieves higher depolarization temperature, even higher than Curie temperature (T_C) and simultaneously a better piezoelectric thermal stability. Through microscopic and macroscopic analysis, the enhancement can be explained by the clamping effect induced by acceptor doping, which is carefully demonstrated by symmetry-conforming short-range ordering tendency theory. Thus, this work reveals the mechanism for enhanced depolarization temperature and piezoelectric thermal stability due to acceptor doping and will help developing new thermal stable lead-free piezoceramics applicable in a wider temperature range.     

Structural and relaxor behavior in lead-free (Ba0.8Sr0.2)Ti1−x(Zn1/3Nb2/3)xO3 ceramics

The Solid solutions of (1−x)Ba_0.8Sr_0.2TiO₃−xBa(Zn_1/3Nb_2/3)O₃ (BST–BZN) with 0.025≤x≤0.15 were prepared by a high temperature solid-state reaction technique. The effects of the Ba(Zn_1/3Nb_2/3)O₃ addition on the phase composition in the B site on structural and dielectric properties was investigated. The room temperature X-ray diffraction analyses of all ceramics revealed a perovskite phase with a composition dependent symmetry. The temperature and frequency dependence of the dielectric permittivity and losses have been explored. While ceramics of compositions x≤0.05 showed normal ferroelectric behavior, while ceramics with x≥0.1 were of relaxor type. It was found that degree of diffuseness and the relaxor effect increased, whereas the transition temperature (T_C or T_m) decreased when both zinc and niobium were introduced in the Ba_0.8Sr_0.2TiO₃ lattice. For the composition with x≥0.1, the frequency depend on T_m, satisfying the Vogel–Fulcher formula, which indicates a relaxor bahavior.     

Raman and dielectric investigation of (Ba0.9−xSrxCa0.1)(Ti0.8Zr0.2)O3 ferroelectric ceramics

Solid solutions of (Ba_0.9−xSr_xCa_0.1)(Ti_0.8Zr_0.2)O₃ (BSCTZ) (0.1≤x≤0.4) were prepared using the conventional solid state reaction method. The effects of the substitution content on the crystallographic structure, phase transition and dielectric properties of the samples were investigated by dielectric and Raman spectroscopy over a wide temperature range from 100 to 500 K. All the samples were noted to undergo a diffuse phase transition from the tetragonal to the cubic phase and to exhibit a relaxor ferroelectric behavior.     

Phase characteristics,microstructure, and electrical properties of (1-x)BaZr0.2Ti0.8O3-(x)(Ba0.7Ca0.3)0.985La0.01TiO3 ceramics

In this study, (1-x)BaZr_0.2Ti_0.8O₃-(x)(Ba_0.7Ca_0.3)_0.985La_0.01TiO₃ ((1-x)BZT-(x)BCLT) ceramics, where x = 0.3, 0.4, 0.5, and 0.6, were prepared employing a conventional solid-state sintering technique. X-ray diffraction patterns and dielectric measurements indicated three phase regions at room temperature, including a single rhombohedral (x = 0.3), a phase coexistence of rhombohedral and tetragonal (x = 0.4), and a single tetragonal structure (x ≥ 0.5). X-ray photoemission spectra at the surface of ceramics confirmed the oxidation state of Ba²⁺, Ca²⁺, Ti⁴⁺, and Zr⁴⁺ ions. Upon BCLT addition, the reduction of the average grain size and the presence of the tetragonal structure significantly affected the dielectric, ferroelectric, and piezoelectric properties of these ceramics. With these results, the composition x = 0.3 showed maximum ε_r′ and ε_m′, whereas the composition x = 0.5 showed maximum P_r, E_c, d₃₃, k_p, and d¹₃₃ factors. These results suggest a new phase diagram for the (1-x)BZT-(x)BCLT system, which could be tuneable by BCLT concentration and might be useful as an alternative material in dielectric, ferroelectric, and piezoelectric devices.     

Electrical and mechanical properties of BZT − xBCT lead-free piezoceramics

In this study, lead-free (1 − x)Ba(Zr_0.2Ti_0.8)O₃ − x(Ba_0.7Ca_0.3)TiO₃ compositions are synthesized via conventional solid oxide route, and the ceramics are fabricated with normal sintering in air. The effects of composition fluctuations on dielectric, piezoelectric, and mechanical properties are investigated. The phase structure and the microstructure are analyzed with X-ray diffraction and scanning electron microscopy. The best dielectric and piezoelectric properties of ε_r = 11 207 and d₃₃ = 330 pC/N were obtained for BZT−0.35BCT and BZT−0.5BCT ceramics, respectively. The mechanical behavior—in terms of Vickers hardness and compressive and flexural strengths—was investigated, and the best mechanical behavior was found in the vicinity of the phase transition boundary with x values between 0.5 and 0.6.     

Mechanism of the Formation of Ba2Ti9O20-Based Phases in the Course of Solid-Phase Interaction in the BaO–TiO2(ZrO2) and Cs2O–BaO–TiO2(ZrO2) Systems

The mechanism of solid-phase interaction in the BaO–TiO₂(ZrO₂) and Cs₂O–BaO–TiO₂(ZrO₂) systems is investigated. It is established that the formation of the Ba₂Ti₉O₂₀ compound and Ba₂Ti₉O₂₀-based solid solutions is a multistage process proceeding through the formation of intermediate phases. The solid-phase interaction in the BaO–TiO₂(ZrO₂) system occurs through the formation of the BaTi₄O₉ intermediate compound. The Ba₂Ti₉O₂₀ single-phase product is formed only in the presence of ZrO₂ (0.82 mol %) upon heat treatment at a temperature of 1250°C for 5 h. In the Cs₂O–BaO–TiO₂(ZrO₂) system, the BaTi₅O₁₁ metastable intermediate phase is formed at the first stage of the solid-phase interaction. The Cs _x Ba_{2 – x/2}Ti_{9 – y} Zr _y O₂₀ single-phase solid solutions are prepared upon heat treatment at 1100°C for 1 h. It is demonstrated that, in the Ba₂Ti₉O₂₀ structure, cesium can isomorphously substitute for barium with the formation of Cs _x Ba_{2 – x/2}Ti_{9 – y} Zr _y O₂₀ solid solutions (0 x 0.8, y = 0 and 0.09).     

Phase transition,microstructure and electrical properties of Fe doped Ba0.70Ca0.30TiO3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics of Ba_0.70Ca_0.30Ti_1?xFe_xO₃ (x=0–0.03) have been synthesized by a conventional solid state reaction method. The influence of Fe content on the microstructure, phase transition, dielectric, ferroelectric, and piezoelectric properties is investigated systematically. The ceramics with x≤0.02 are diphasic composites of tetragonal Ba_0.80Ca_0.20TiO₃:Fe and orthorhombic Ba_0.07Ca_0.93TiO₃:Fe solid solutions. The tetragonal phase is gradually suppressed as x increases, the ceramic with x=0.03 is found to have diphasic pseudocubic and orthorhombic phases. And the grain size is dependent on Fe content significantly. Introduction of Fe at B-sites improves the densification and decreases the sintering temperature. As x increases from 0 to 0.03, the room temperature relative dielectric permittivity enhances, dielectric loss decreases, and the Curie temperature decreases monotonically from 128 °C to 58 °C. However, the ferroelectricity enhances slightly and reaches the maximum near x=0.005, and then weakens with increasing x. On the other hand, the piezoelectric coefficient (d₃₃) and the electromechanical coupling coefficient (k_p) decrease simultaneously with increasing x, whereas the mechanical quality factor (Q_m) increases significantly. The structure–electrical properties relationship is discussed intensively to give more information on (Ba,Ca)TiO₃-based lead-free piezoelectric ceramics.     

Phase Transition Behavior and Large Piezoelectricity Near the Morphotropic Phase Boundary of Lead‐Free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Ceramics

The phase transition behavior and piezoelectric properties of (Ba_1?xCa_x)(Zr_0.1Ti_0.9)O₃ and (Ba_0.85Ca_0.15)(Zr_yTi_1?y)O₃ ceramics were investigated in this work to find out the potential factors contributing to large piezoelectricity. It was found that the morphotropic phase boundary (MPB) of (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ ceramics was closely related to the presence of an intermediate phase (considered as orthorhombic phase in this work) between rhombohedral (R) and tetragonal (T) phases at a narrow region, which could be carefully adjusted by the temperature and contents of Ca and Zr in the composition. In addition, the maximum piezoelectric and electromechanical coupling coefficients (with d₃₃ = 572 pC/N and k_p = 0.57) were observed near the MPB region close to T phase side, which might be intimately related to the presence of the intermediate phase. This investigation yielded a new sight to understand the mechanism of enhanced piezoelectricity near the MPB.     

A-site compositional modulation in barium titanate based relaxor ceramics to achieve simultaneously high energy density and efficiency

Dielectric ceramics capacitors (DCC) with excellent energy storage performance (ESP) and charge-discharge performance (CDP) is very critical in the field of advanced electronics and power systems. A strategy that improves the ESP of 0.6Ba(Zr_0.2Ti_0.8)O₃-0.4(Na_0.5Bi_0.5)TiO₃ (BZT-NBT) ceramics was proposed via Sr²⁺ doping. XRD and SEM results confirmed that 0.6(Ba_1-xSr_x)(Zr_0.2Ti_0.8)O₃-0.4(Na_0.5Bi_0.5)TiO₃ (x = 0, 0.1, 0.2, 0.3, 0.4) (BSZT-NBT) ceramics formed dense and stable perovskite solid solutions. The relaxor ferroelectric (RFE) properties of BSZT-NBT ceramics were also well proved by dielectric behaviors. A large recoverable energy storage density (W_rec) and large efficiency (η) of 3.72 J cm⁻³ and 94.03 % (x = 0.3) can be simultaneously obtained at 289 kV cm^-1. ESP of BSZT-NBT (x = 0.3) ceramics at 180 kV cm^-1 exhibit good frequency (1−100 Hz) and temperature (room temperature (RT)-120 °C) stability. BSZT-NBT (x = 0.3) ceramics at 120 kV cm⁻¹ exhibit a prominent power density (P_D) and rapid discharge rate (t_0.9) of of 37.62 MW cm⁻³ and 70.6 ns. All evidences confirm that introduction of Sr²⁺ into A-site of barium titanate-based ceramics could effectively improve ESP.     

Energy storage property of (Pb0.97La0.02)(Zr0.5Sn0.4Ti0.1)O3-(Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics: Effects of antiferroelectric-relaxor transition and improved breakdown strength

(1-x)(Pb_0.97La_0.02)(Zr_0.5Sn_0.4Ti_0.1)O₃-x(Na_0.5Bi_0.5)_0.94Ba_0.06TiO₃ (x = 0 ∼ 0.4) ceramics have been prepared and investigated. The ceramics consist of perovskite solid solution matrix and precipitated, isolated SnO₂ particle, resulting in 0–3 type composite structure. With increasing x value, the room temperature crystal structure of perovskite solid solution transforms from tetragonal to pseudocubic, therefore, the electrical property evaluates form robust antiferroelectric at x = 0, metastable antiferroelectric at x = 0.1, and then relaxor ferroelectric at x > 0.1. Moreover, the breakdown strength is enhanced due to the composite structure and reaches maximum value of 190 kV/cm at x = 0.2. Both the phase transition and enhanced breakdown strength are helpful to improve energy storage property, the x = 0.2 ceramic shows largest recoverable energy density w_rec of 1.84 J/cm³, discharge efficiency $\eta$ of 86.6 %. Especially, both w_rec and $\eta$ illustrates significantly improved thermal stability within 25−125 °C.     

Creating adjoining polymorphic phase transition (PPT) regions in ferroelectric (Ba,Sr)(Zr,Ti)O3 ceramics

In this work, we report the polymorphic phase transitions(PPT) in ferroelectric Ba_0.95Sr_0.05Zr_xTi_(1-x)O₃ (BSZT, x = 0.01–0.10) ceramics synthesized by using a solid-state reaction method. The doping elements and composition ratios were selected to create adjoining PPT phase boundaries near room temperature, hence to achieve a broadened peak of piezoelectric performance with respect to composition. The temperature-composition phase diagram was constructed and the effects of PPT on the electromechanical and ferroelectric properties of the ceramics were investigated. It was revealed that the two adjacent PPT regions at room temperature showed different characteristics in property enhancement. However, due to the proximity of the phase boundaries, Ba_0.95Sr_0.05Zr_xTi_(1-x)O₃ ceramics in a fairly broad range of compositions (0.02 ≤ x ≤ 0.07) showed excellent piezoelectric properties, including a large piezoelectric constant (312 pC/N ≤ d₃₃ ≤ 365 pC/N) and a high electromechanical coupling coefficient k_p (0.42 ≤ k_p ≤ 0.49).     

Cytotoxicity,chemical stability,and surface properties of ferroelectric ceramics for biomaterials

Surface chemistry and topo‐physical properties determine the interactions of biomaterials with their physiological environment. Ferroelectrics hold great promise as the next generation of scaffolds for tissue repair since they feature tunable surface electrical charges, piezoelectricity, and sensing capabilities. We investigate the topography, wettability, chemical stability, and cytotoxicity in salient ferroelectric systems such as (1?x) (Na_1/2Bi_1/2)TiO₃–xBaTiO₃, (1?x)Ba(Zr_0.2Ti_0.8)O₃?x(Ba_0.7Ca_0.3)TiO₃, and Pb(Zr,Ti)O₃ to test their suitability as biomaterials. The lead‐free ferroelectrics promote in vitro cell viability and proliferation to a considerably high extent. 0.94 mol % (Na_1/2Bi_1/2)TiO₃–0.06 mol% BaTiO₃ showed the greatest potential leading to a cell viability of (149 ± 30)% and DNA synthesis of (299 ± 85)% in comparison to the reference. Lead leaching from Pb(Zr,Ti)O₃ negatively affected the cultured cells. Wettability and chemical stability are key factors that determine the cytotoxicity of ferroelectrics. These variables have to be considered in the design of novel electroactive scaffolds based on ferroelectric ceramics.     

Non-stoichiometric BZT-BCT ferroelectrics with visible/near-infrared photoresponse for broadband photodetection

The bulk photovoltaic effect in ferroelectric materials exhibits great potential in photoelectric applications. However, their photoresponse is generally limited to the UV region due to the wide bandgap feature of most perovskite ferroelectric materials, while the narrowing of bandgap is often accompanied by the degradation or even extinction of the ferroelectric polarization. Herein, 0.5Ba(Zr_0.2Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ (BZT-BCT) with bandgap of 2.4 eV arising from the existence of Ti³⁺ is prepared, and then titanium vacancies are introduced to BZT-BCT ferroelectric solid solutions through B-site off-stoichiometry (0.5Ba(Zr_0.2Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)Ti_{1 − x%}O₃, BZT-BCT_{1 − x%}) to further tune the bandgap. Lowest bandgap of 2.1 eV with near-infrared (NIR) absorption is obtained for BZT-BCT_0.990 composition. Moreover, both the ferroelectricity and piezoelectricity (P_r = 14.3 μC/cm², d₃₃ = 415 pC/N) are well maintained after mitigating the effect of the increased oxygen vacancies associated with Ti-deficiency on the spontaneous polarization by oxygen-annealing treatment. More specifically, the oxygen-annealing BZT-BCT_0.985 composition, showing at least 2.4-fold photovoltage and 2.2-fold photocurrent of the pristine BZT-BCT ceramic, exhibits excellent transient pyroelectric current and stable photovoltaic current under xenon, NIR, and monochromatic visible lights. The photoelectric device based on the oxygen-annealing BZT-BCT_0.985 ceramic performs wide-spectrum photodetection properties from 405 nm light to NIR light, which makes it a potential candidate for self-powered photodetector applications.