Search

Tin‐based perovskite is a competitive analog with lead halide perovskite, but there are significant gaps in power conversion efficiency (PCE) and stability between tin‐ and lead‐based perovskite solar cells. The characteristics of the easy oxidizability of Sn2+ and the rapid crystal growth for tin‐based perovskite are two major issues remained to be overcome. Herein, an additive (4‐pyridylamidoxime (4‐PyAO)) with multiple functional groups is introduced in the perovskite precursor solution. The oxidation of Sn2+ and the crystallization rate of perovskite are both retarded by 4‐PyAO addition. The prepared perovskite film is of high quality with fewer trap states and carrier recombination, and carrier extraction and transfer between the perovskite film and the adjacent carrier transport layer also become more efficient. As a result, the corresponding devices deliver the highest PCE of 9.02%, accompanied by short‐circuit current density, open‐circuit voltage, and fill factor of 19.90 mA cm−2, 0.63 V, and 72.48%, respectively. More importantly, the best device without encapsulation maintains 92% of its initial PCE after 2500 h aging test in nitrogen atmosphere, which may be attributed to a synergic effect among the different functional groups. [ABSTRACT FROM AUTHOR]

0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMNT) piezoelectric ceramics were prepared by traditional ceramic processing via B-site oxide mixing route and columbite precursor method using oxides as raw materials, where the influences of MgO purity, whether heat treatment of MgO and synthesis techniques were studied. When using MgO with purity of 98%, the amount of pyrochlore phase in the sintered PMNT ceramics is rather high no matter what synthesis techniques used. Phase-pure perovskite PMNT ceramics can be prepared via the columbite precursor method using 99.99% MgO as raw material after pre-heated at 1200 °C for 4 h. All the PMNT ceramics exhibit rhombohedral perovskite structure with composition approaching the morphotropic phase boundary. The ceramics' density is affected little by pyrochlore impurity, whereas the sintering temperature range is narrow and the 1245 °C sintered phase-pure PMNT ceramics have the largest relative density and compact micro-morphology. The PMNT ceramics present apparent relaxor ferroelectrics characteristic, where the samples with low content of pyrochlore phase or with phase-pure perovskite structure have excellent dielectric property. The samples present easy polarization characteristic, in which the PMNT ceramics with high purity or phase-pure perovskite phase have excellent piezoelectricity. [ABSTRACT FROM AUTHOR]

0.55 Bi(Ni0.5Ti0.5)O3–0.05BiFeO3–0.4PbTiO3 ((0.55BNT–0.05BF–0.4PT)) ceramics were prepared by low-temperature solid-phase sintering method due to adding sintering additives. The 800 °C calcined powders present relatively pure perovskite structure. The 990 °C–1030 °C sintered ceramics exhibit pure perovskite structure, and the density is increased significantly as compared with the undoped ones due to the addition of 0.5 wt% LiBO2. The "0.55BNT–0.05BF–0.4PT" samples sintered at 1010 °C have large density, compact microstructural morphology, high Curie temperature and excellent electrical properties. The ceramics show apparent relaxor ferroelectric behavior and dielectric relaxation characteristic. Grains conduction contributes mainly to the high-temperature conduction, which can be attributed to the migration of oxygen vacancies produced due to the evaporation of ions during sintering. [ABSTRACT FROM AUTHOR]

Large-size and high-quality 0.85Pb(Zn1/3Nb2/3)O3–0.15PbTiO3 (0.85PZN-0.15PT) single crystals were grown by a modified Bridgman method using an allomeric 0.69Pb(Mg1/3Nb2/3)O3–0.31PbTiO3 single crystal as a seed. The as-grown 0.85PZN-0.15PT single crystals exhibit a tetragonal perovskite structure, which changes wholly into a cubic structure between 190 and 215 °C confirmed by high-temperature x-ray diffraction measurement. 0.85PZN-0.15PT exhibits sharp dielectric-response peaks with slight dielectric frequency dispersion where the ferroelectric-paraelectric phase transition is nearly first order. Polarization induces an additional dielectric anomaly around 147 °C accompanied by the increase in Curie temperature (TC), the decrease in the value of dielectric maximum ([variant_greek_epsilon]m), and the enhancement of frequency dispersion, which can be assigned to the orientation of a ferroelectric domain or a macro-micro domain transition upon heating. The [001]-oriented 0.85PZN-0.15PT crystal planes exhibit excellent electrical properties, where remanent polarization Pr is 58.27 μC/cm2 and piezoelectric constant d33 is around 530–570 pC/N. Pyroelectric coefficient p, detectivity, and voltage responsivity figures of merit Fd and Fv of the 0.85PZN-0.15PT single crystals are 460 μC/K m2, 13.14 μPa-1/2, and 0.0302 m2/C, respectively, which increase greatly over the temperature range measured. It is needed to improve the temperature stability and the voltage responsivity to meet the requirements of practical applications. 0.85PZN-0.15PT exhibits rather high transparency, with the ultraviolet cut-off edge near 380 nm indicating a low-lying electronic energy gap of ∼3.16 eV. The infrared-absorption band occurs at 597 cm-1, which can be attributed to the normal vibration of the [Zn1/3Nb2/3]/TiO3 group. [ABSTRACT FROM AUTHOR]

The high-Curie temperature (T C ) 0.15Pb(Mg 1/3 Nb 2/3 )O 3 -0.38PbHfO 3 -0.47PbTiO 3 (PMN-PH-PT) piezoelectric ceramics were prepared via the citrate method. The rather homogeneous microstructure with nm-scale particles of the PMN-PH-PT precursor powders were attained with a calcining temperature ranging from 650 °C to 800 °C and pure perovskite structure of the PMN-PH-PT ceramics were prepared by the citrate method sintered from 1225 °C to 1265 °C. The content of the rhombohedral phase in the PMN-PH-PT ceramics sintered at 1245 °C increases first and then decreases with elevating the calcining temperature, and all the synthesized PMN-PH-PT ceramics have high density. The PMN-PH-PT ceramics exhibit complex dielectric behavior, in which the PMN-PH-PT ceramics calcined at 800 °C and sintered at 1245 °C exhibit the best dielectric properties with ε m = 26269 and T C /T m = 297 °C. The nonlinear dielectric behavior of the PMN-PH-PT ceramics was successfully studied by the Rayleigh relation, which also reveals a polymorphic phase transition (PPT) resulted from the polar nanoregions (PNRs) in the PMN-PH-PT ferroelectric ceramics. Due to the mutual influences of grain size, domain configuration and microstructure morphology, the electrical properties of the synthesized PMN-PH-PT ceramics are influenced greatly, in which the PMN-PH-PT ceramics calcined at 775 °C and sintered 1245 °C exhibit the optimum ferroelectric and piezoelectric properties. The piezoelectricity of the PMN-PH-PT ceramics is superior to the same compositional ceramics synthesized by the columbite precursor method, which can be attributed to the morphotropic phase boundary (MPB) effect and densified microstructure induced by the wet-chemical citrate method. The PMN-PH-PT ceramics prepared by the citrate method exhibit excellent thermal stability of the piezoelectric and ferroelectric properties surpassing the common usage temperatures, indicating their promising transducer applications under elevated environmental temperatures. [ABSTRACT FROM AUTHOR]

0.14 at% Mn-doped 0.95(Na 1/2Bi 1/2)TiO 3-0.05BaTiO 3 (0.95NBT-0.05BT) lead-free single crystals were grown by a top-seeded solution growth method (TSSG). X-ray powder diffraction measurement showed that the as-grown single crystals exhibit rhombohedral perovskite structure with apparent distortion. With the increase of temperature, successive structural phase transitions occur in the Mn-doped 0.95NBT-0.05BT single crystals. After poling, apparent dielectric anomaly is induced accompanied by the increase of the character of diffuse phase transition and the decrease of the value of dielectric constant. The Mn-doped 0.95NBT-0.05BT single crystals exhibit complex domain structure, in which micro and macro domains coexist with statistically 4 mm symmetry. The Mn-doped 0.95NBT-0.05BT lead-free single crystals exhibit excellent piezoelectric and pyroelectric properties, which will lead to promising advance in piezoelectric and pyroelectric applications. The infrared-absorption band occurred around 630.6 cm −1 can be assigned to the “stretching” normal vibration of [Na 1/2Bi 1/2]/Ti-O group. The three diffused Raman bands centered around 300, 560 and 800 cm −1 can be attributed to F2g [TiO 6] bending vibration, A1g [TiO 6] stretching vibration and “soft mode” mixed by bending and stretching vibrations. [ABSTRACT FROM AUTHOR]

(1 − x)Pb(Mg1/3Nb2/3)O3- xPbTiO3 (PMN-PT, x = 0.2-0.4) ferroelectric (FE) ceramics were prepared by the partial oxalate route. The synthesized PMN-PT ceramics exhibit high density and densified microstructure although slight content of pyrochlore phase impurity exists. With the increase of PbTiO3 (PT) content, the phase structure of the PMN-PT ceramics changes gradually from rhombohedral perovskite structure, across the morphotropic phase boundary (MPB) composition and to tetragonal perovskite structure. The FE structural phase transition of PMN-PT changes gradually from the diffused ferroelectric phase transition (FPT) of typical relaxor FEs to nearly first-order FPT of normal FEs, confirmed by dielectric and FE properties measurements. The PMN-PT ceramics exhibit excellent dielectric and piezoelectric properties, and fully developed and saturated P- E hysteresis loops, in which the MPB effects are clearly shown by these electrical properties. The MPB composition of the PMN-PT system is determined locating at x = 0.31-0.33 by XRD measurement and electrical properties measurements. [ABSTRACT FROM AUTHOR]

A large-size 0.88NaBiTiO-0.12KBiTiO lead-free piezoelectric single crystal with dimensions of ∅30 mm ×10 mm was successfully grown by the top-seeded solution growth method. X-ray powder diffraction measurement showed that the as-grown crystal possesses a rhombohedral perovskite structure at room temperature. The temperature dependence of dielectric constant and loss, polarization hysteresis loop, electric-field-induced strain, and the electromechanical coupling property were investigated for the <100>-oriented as-grown crystal. The remanent polarization P, the piezoelectric constant d, and the electromechanical coupling coefficient k at room temperature are 13.8 pC/cm, 205 pC/N, and 51 %, respectively. The maximum strain of 0.23 % was obtained under 30 kV/cm. The temperature dependence of k demonstrated a relatively stable thermal electromechanical coupling property over the temperature range of 20-150 °C. [ABSTRACT FROM AUTHOR]

The 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3(0.69PMN-0.31PT) ceramics were prepared by a partial oxalate route via the columbite precursor method, a modified columbite precursor method and the B-site oxide mixing route. X-ray diffraction (XRD) measurement confirmed that pure-phase perovskite 0.69PMN-0.31PT ceramics were prepared by the modified columbite precursor method. All the sintered 0.69PMN-0.31PT ceramics exhibit large relative density, and rather homogenous and densified microstructure morphology, in which the 0.69PMN-0.31PT ceramics prepared by the modified columbite precursor method exhibit large bulk density, being 7.9015 g/cm3, which reaches 96.74% of the theoretical density. The largest value of dielectric constant maximum (ϵm) appears in the 0.69PMN-0.31PT ceramics prepared by the B-site oxide mixing route, being 32232 at 1 kHz. All the synthesized 0.69PMN-0.31PT ceramics exhibit typical ferroelectric phase transition with slightly diffused character, fully developed, saturated and symmetric P-E hysteresis loops, and excellent piezoelectric property. Ceramic processings exert great effects on electrical properties of the synthesized ceramics. Comparatively, the 0.69PMN-0.31PT ceramics prepared by the B-site oxide mixing route exhibit excellent electrical properties. [ABSTRACT FROM PUBLISHER]

Phase-pure perovskite structure (KxLa0.05-x)Ba0.95TiO3 ceramics were prepared by the conventional solid-state reaction method. With the increase of the ratio of K/La, crystal structure of the (KxLa0.05-x)Ba0.95TiO3 ceramics changes gradually from pseudo-cubic perovskite structure to tetragonal one. The sintered (KxLa0.05-x)Ba0.95TiO3 ceramics exhibit rather high relative density and rather homogenous microstructure morphology composed of submicron grains. With the decrease of the ratio of K/La, the temperature of dielectric constant maximum (TC or Tm) decreases almost linearly, and the dielectric response character of the (KxLa0.05-x)Ba0.95TiO3 ceramics changes from narrow and sharp dielectric peaks to broad and diffused ones gradually accompanied by the increase of dielectric frequency dispersion. The (KxLa0.05-x)Ba0.95TiO3 ceramics exhibit rather slim P-E hysteresis loops with slight character of asymmetry. Via adjusting the ratio of K/La, the acceptor and donor doping states are tailored, therefore, excellent ferroelectric and piezoelectric properties can be obtained in the (KxLa0.05-x)Ba0.95TiO3 ceramics. [ABSTRACT FROM PUBLISHER]

Abstract: The ternary system of 0.56Pb(Ni1/3Nb2/3)O3–0.10Pb(Zn1/3Nb2/3)O3–0.34PbTiO3 (0.56PNN–0.10PZN–0.34PT) ceramics were prepared by conventional solid-state reaction method via straight mixed oxide method, columbite precursor method and B-site oxide mixing route. X-ray diffraction (XRD) measurement demonstrated that both the tetragonal and rhombohedral phases coexist in the B-site oxide mixing route prepared ceramics accompanied by the largest content of perovskite phase of 95.18%. The 0.56PNN–0.10PZN–0.34PT ceramics prepared by the straight mixed oxide method and the B-site oxide mixing route exhibit rather homogeneous microstructure. As a comparison, in the columbite precursor method prepared ceramics nebulous granules and octahedral or other polyhedral morphology grains are observed. All the sintered ceramics exhibit diffused ferroelectric phase transition where the dielectric response peaks are broad, diffused and strongly frequency dependent. However, the temperature of dielectric maximum (T m) increases greatly from 398.0K of the 0.56PNN–0.10PZN–0.34PT ceramics prepared by the B-site oxide mixing route to 423.3K of the ones prepared by the straight mixed oxide method. Saturated and symmetric P–E hysteresis loops are observed in all the sintered ceramics, where the B-site oxide mixing route prepared ceramics exhibit large value of remanent polarization (P r) of 17.13μC/cm2 and the least value of coercive field (E c) of 11.99kV/cm. Piezoelectric constant (d 33) exhibits the largest value of 449pC/N for the ceramics prepared by the B-site oxide mixing route. Such results are related to the phase composition, density and porosity of the ceramics. [Copyright &y& Elsevier]

Mn-doped 0.948NaBiTiO-0.052BaTiO (NBBT94.8/5.2) lead-free single crystal with excellent piezoelectric and electromechanical coupling properties was successfully grown by top-seeded solution growth method (TSSG). X-ray powder diffraction measurement showed that the as-grown crystal possesses rhombohedral perovskite structure. The Mn-doped NBBT94.8/5.2 single crystal exhibits apparent diffused dielectric behavior, in which the diffusiveness index α is 1.99 for the [001]-oriented crystal planes. A notable thermal hysteresis is disclosed for the rhombohedral-tetragonal phase transition between heating and cooling studies in the dielectric property. The electromechanical coupling coefficients of Mn-doped NBBT94.8/5.2 were determined experimentally using the resonance-antiresonance technique. The room-temperature electromechanical coupling coefficients k, k, k, k are 35.9%, 35.5%, 68.5%, 58.7%, respectively. The room-temperature piezoelectric constants d, d reach as high as 457, 138 pC/N respectively. The value of k increases slightly with the increase of temperature from −80 to 70°C, demonstrating a relatively stable thermal electromechanical coupling property. [ABSTRACT FROM AUTHOR]

(Na1/2K1/2)NbO3 (NKN) and 0.95NKN-0.05AB (AB = CaTiO3 (CT), LiSbO3 (LS), (Ba1/2Sr1/2)TiO3 (BST)) lead-free piezoelectric ceramics were prepared by conventional solid-state reaction method. XRD measurement confirmed that the second component doped NKN ceramics exhibit pure tetragonal perovskite structure. The addition of the second component greatly increases relative density and improves electrical properties of the NKN ceramics. Especially, the 0.95NKN-0.05LS ceramics exhibit high densification, being 93.16% of the theoretical density, rather homogenous micromorphology, and excellent integral electrical properties, where the value of dielectric constant maximum εm at 1kHz is 4780, remanent polarization Pr is 19.66μC/cm2 and piezoelectric constant d33 is 194pC/N. [ABSTRACT FROM AUTHOR]

Abstract: Pure phase perovskite 0.94(Na1/2K1/2)NbO3–0.03LiSbO3–0.03LiTaO3 (0.94NKN–0.03LS–0.03LT) lead-free piezoelectric ceramics were prepared by the conventional solid-state reaction method. Due to the co-addition of LiSbO3–LiTaO3, the 0.94NKN–0.03LS–0.03LT ceramics prepared by atmosphere sintering at 1040°C exhibit high relative density, being 94.73%, and rather homogenous microstructure. X-ray diffraction (XRD) measurement confirmed that the sintered ceramics exhibit pure tetragonal perovskite structure. The 0.94NKN–0.03LS–0.03LT ceramics exhibit excellent integral electrical properties, in which the value of piezoelectric constant d 33 is 228pC/N, the electromechanical coupling factors K p and K t are 0.220 and 0.230, respectively, the mechanical quality factor Q m is 32.19, and the remnant polarization P r is 23.06μC/cm2. Such excellent electrical properties are considered as correlating with the high relative density of the synthesized ceramics induced by the co-doping of LiSbO3–LiTaO3. [ABSTRACT FROM AUTHOR]

Abstract: Phase pure perovskite (1−x−y)Pb(Ni1/3Nb2/3)O3–xPb(Zn1/3Nb2/3)O3–yPbTiO3 (PNN–PZN–PT) ferroelectric ceramics were prepared by conventional solid-state reaction method via a B-site oxide mixing route. The PNN–PZN–PT ceramics sintered at the optimized condition of 1185°C for 2h exhibit high relative density and rather homogenous microstructure. With the increase of PbTiO3 (PT) content, crystal structure and electrical properties of the synthesized PNN–PZN–PT ceramics exhibit successive phase transformation. A morphotropic phase boundary (MPB) is supposed to form in (0.9−x)PNN–0.1PZN–xPT at a region of x=32–36mol% confirmed by X-ray diffraction (XRD) measurement and dielectric measurement. The MPB composition can be pictured as providing a “bridge” connecting rhombohedral ferroelectric (FE) phase and tetragonal one since crystal structure of the MPB composition is similar to both the rhombohedral and tetragonal lattices. Dielectric response of the sintered PNN–PZN–PT ceramics also exhibits successive phase-transition character. 0.64PNN–0.1PZN–0.26PT exhibits broad, diffused and frequency dependent dielectric peaks indicating a character of diffused FE–paraelectric (PE) phase transition of relaxor ferroelectrics and 0.40PNN–0.1PZN–0.50PT exhibits narrow, sharp and frequency independent dielectric peaks indicating a character of first-order FE–PE phase transition of normal ferroelectrics. The FE–PE phase transition of 0.56PNN–0.1PZN–0.34PT is nearly first-order with some diffused character, which also exhibits the largest value of piezoelectric constant d 33 of 462pC/N. [Copyright &y& Elsevier]

Abstract: Lead iron scandium niobate, Pb(Fe1/4Sc1/4Nb1/2)O3 (PFScN), ceramics with pure perovskite phase were produced by conventional solid-state reaction method via a B-site oxide mixing route. Attention is focused on synthesis conditions, where sintering temperature exhibits a pronounced effect on phase formation, density, microstructure and physical properties of the sintered PFScN ceramics. Large bulk density (>95% of the theoretical density) and optimized dielectric properties can be obtained under sintering conditions of 1140–1180°C for 2h. Although synthesis conditions have been tailored to optimization, strong frequency dispersion of the dielectric behavior is observed in the sintered PFScN ceramics, which is considered correlating with the possible existence of residual semi-conductive FeNbO4 and/or ScNbO4 compounds and the thermally activated space-charge polarization resulted from the partial reduction of Fe3+ to Fe2+ ions during sintering. [Copyright &y& Elsevier]

Abstract: Pure rhombohedral perovskite 0.8Pb(Mg1/3Nb2/3)O3–0.2PbTiO3 (0.8PMN–0.2PT) ceramics were prepared by the reaction-sintering method. The synthesized 0.8PMN–0.2PT ceramics exhibit very high relative density. At room temperature, dielectric constant and loss tangent of the 0.8PMN–0.2PT ceramics are 2360 and 0.0434 at 100Hz, respectively, and pyroelectric coefficient is 1337μC/Km2″. The calculated detectivity and voltage responsivity figures of merit F d and F v are 16.81μPa−1/2 and 0.0244m2/C, respectively, which increase slightly over the frequency range 100–2000Hz. Such investigation reveals that high-performance pyroelectric materials can be obtained in low production cost, which provides promising candidates for infrared detectors and other pyroelectric applications. [Copyright &y& Elsevier]

High Curie temperature (T C ) xBi(Ni 1/2 Ti 1/2 )O 3 -(1-x)Pb(Zr 1/2 Ti 1/2 )O 3 (xBNT-(1-x)PZT, BNT-PZT) piezoelectric ceramics were prepared by the conventional ceramic processing. The composition-induced morphotropic phase boundary (MPB) and its influences on structure and electrical performance were investigated. The synthesized BNT-PZT ceramics exhibit rather pure perovskite structure, and densified microstructure morphology with uniform elementals distribution in both grains and grain boundaries. With increasing the content of Bi(Ni 1/2 Ti 1/2 )O 3 (BNT), crystal structure of the BNT-PZT ceramics transform from tetragonal phase to rhombohedral phase, and dielectric response peaks change from narrow shape to very broad shape but all presenting dielectric frequency dispersion. The diffused and relaxation dielectric behavior can be fitted well by the quadratic law, and the Vogel-Fulcher law fitting provides additional information on the relaxation characteristic. The MPB effects are confirmed further by ferroelectric and piezoelectric properties measurements. High-T C combined with excellent piezoelectric performance can be realized in the BNT-PZT system, which presents promising applications in geothermal exploration, aerospace and related elevated temperatures fields. [ABSTRACT FROM AUTHOR]

1 mol% Sr and 1 mol% Sn co-doped (Ba 0.84 Ca 0.15 Sr 0.01 )(Ti 0.90 Zr 0.09 Sn 0.01 )O 3 (BCSTZS) ceramics were prepared by the conventional solid-state reaction method. The sintered BCSTZS ceramics exhibit pure perovskite structure with composition locating at the rhombohedral side around the morphotropic phase boundary (MPB) of the BCZT system. With the increase of sintering temperature, the grains grow up, porosity eliminates and microstructure becomes dense accompanied by the improvement of electrical properties of the synthesized BCSTZS ceramics. Although the grain size of the BCSTZS ceramics sintered at elevated temperatures is rather “small”, they still exhibit excellent electrical properties, which can be attributed to the MPB effect and the dense microstructure induced by the Sr and Sn co-doping. The BCSTZS ceramics sintered at 1550 °C exhibit improved thermal stability of the piezoelectric and ferroelectric properties within the common usage temperatures, indicating that the BCSTZS ceramics are promising lead-free candidates for the widely used lead-based piezoelectric materials. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid perovskites are a promising candidate for fabricating high-efficiency solar cells. In this work, well-dispersed ternary oxide BaSnO 3 (BSO) nanoparticles with high crystallinity were successfully synthesized by a facile peroxide-precipitate route. And then BSO was first used as an efficient electron-transporting layer in planar perovskite solar cells. Influences of the coverage, roughness and thickness of planar BSO layer on the photovoltaic performance of the solar cells were systemically investigated. It is found that better coverage of BSO layer on the transparent oxide electrodes can significant reduce current leakage and suitable thickness of electron-transporting layer is favorable to reduce series resistance. Both of them contribute to the improved power conversion efficiency of cell devices. Additionally, the BSO-based device exhibits a comparable device performances to the TiO 2 one, which can be ascribed to the efficient charge extraction as BSO/perovskite interfaces, the low charge transfer resistance and the suppressed carrier recombination. The optimized BSO-based planar perovskite solar cells exhibits power conversion efficiency of 10.96% with J sc of 17.45 mA/cm 2 , V oc of 0.986 V and FF of 0.637. Thus, this work will pave the way for employing ternary oxide as electron-transporting material for high-performance perovskite solar cells. [ABSTRACT FROM AUTHOR]

Organometallic halide perovskite solar cells have considerable potential to be manufactured as low-cost and visible-light-semitransparent modules by reducing the thickness of the perovskite films for building-integrated photovoltaics. However, perovskite films often suffer from voids and roughness, inducing depressed photovoltaic performance, and this problem is even more severe for thinner perovskite films. Herein, a poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) additive is incorporated into CH 3 NH 3 PbI 3 precursor solutions to control the crystal growth of a visible-light-semitransparent perovskite layer (thickness: ~150 nm) in a one-step deposition process. The characterization results show that the coverage and smoothness of the perovskite films can be significantly improved, and the perovskite crystal boundaries are also reduced by introducing a moderate amount of PVDF-HFP. When the precursor solution containing 12 mg/mL PVDF-HFP, the highest power conversion efficiencies of 10.6% and 8.8% (backward scan) is achieved for the photovoltaic devices with 80 and 20 nm-thick Au electrode, respectively, which is over 30% higher than that of the PVDF-HFP-free control. Time-resolved photoluminescence and electrochemical impedance spectroscopy characterizations further demonstrate that the PVDF-HFP additive can improve the carrier lifetimes and reduce the charge transfer resistance, which contributes to the enhanced photovoltaic performance. Thus, we propose a strategy specific to a high-quality visible-light-semitransparent perovskite layer and for high-performance perovskite solar-cell preparation. [ABSTRACT FROM AUTHOR]

CsPbI 2 Br perovskites are promising candidates for photovoltaic applications owing to the trade-off between the optoelectronic properties and phase stability of cesium-based inorganic perovskites. However, the major shortcomings of CsPbI 2 Br perovskite solar cells (PSCs), namely energy loss and poor moisture resistance, still need to be addressed. In this work, reversible degradation-assisted decoration with Cs 4 PbBr 6 nanocrystals (NCs) is used to passivate the perovskite/hole transporting material (HTM) interface. Moisture-induced Cs 4 PbBr 6 decomposition products (CsPbBr 3 and CsBr) and CsPbI 2− x Br 1+ x (x > 0), generated as a result of halide anion exchange between CsPbI 2 Br and Cs 4 PbBr 6 or its decomposition products, are found to improve the quality of the CsPbI 2 Br film and suppress the trap state density. In addition, the decoration achieves desirable energy-level alignments at the CsPbI 2 Br/HTM interface and raises the Fermi level of the CsPbI 2 Br film, thereby strengthening the built-in electric field between the perovskite and HTM. As a result, the optimized CsPbI 2 Br PSC has a champion efficiency of 15.52% with an open-circuit voltage of 1.30 V (mean value: 1.29 V). The unencapsulated CsPbI 2 Br film and device both exhibit high air stability (∼40% humidity), and the latter retains 90% of its initial efficiency after a 500 h aging test. [Display omitted] • Decoration with Cs 4 PbBr 6 nanocrystals and subsequent reversible degradation. • The decoration improves crystal quality and suppresses trap state density. • Strengthening of the built-in electric field are also achieved by the decoration. • PSC V OC and moisture stability are simultaneously improved. [ABSTRACT FROM AUTHOR]

Highlights: [•] Oxide doping and B-site oxide mixing route are good for synthesizing ferroelectrics. [•] Pb(Fe1/4Sc1/4Nb1/2)O3/PFSN ceramics exhibit pure rhombohedral perovskite structure. [•] The MnO2- and Li2CO3-doped PFSN ceramics exhibit improved electrical properties. [•] The doped PFSN ceramics exhibit excellent pyroelectric property. [•] The doped PFSN ceramics exhibit promising applications for pyroelectric devices. [ABSTRACT FROM AUTHOR]