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ZrSe2, a member of the group-IVB transition metal dichalcogenides, shows favorable performance in optoelectronic applications. Here, the photoelectric properties of ZrSe2 under high pressure have been systematically investigated. At 13.5 GPa, the photocurrent of ZrSe2 increases three orders of magnitude greater than its initial value. Interestingly, above 23.5 GPa, ZrSe2 exhibits a negative photocurrent response, which can be attributed to the photothermal effect caused by pressure-induced metallization. This study demonstrates the critical role of pressure in regulating the optoelectronic properties of layered materials and the potential application of layered ZrSe2 in pressure-responsive optoelectronic devices. [ABSTRACT FROM AUTHOR]

As a typical organic semiconductor material, rubrene plays a prominent role in the field of optoelectronic devices. Here, a notable photoluminescence (PL) and photocurrent enhancement of rubrene by 8‐ and 2.5‐fold is reported under compression, respectively. The shortening of the π−π stacking distance and the twisting of the lateral phenyl are crucial reasons for the decrease in the bandgap, resulting in the enhancement of PL emission and photocurrent. Pressure can effectively suppress the excitons transition from a free exciton state to a self‐trapped exciton state and improve the emission efficiency. The photocurrent is subject to dual regulation by bandgap and resistance. Interestingly, rubrene undergoes an electronic structure transition at about 4.8 GPa, which is responsible for the weakening of PL emission and photocurrent. This work provides a strategy for optimizing the performance of rubrene‐based optoelectronic devices and designing novel optoelectronic materials. [ABSTRACT FROM AUTHOR]

This work investigates the impact of pressure on the structural, optical properties, and electronic structure of CsPbBr3 quantum dots (QDs) using steady‐state photoluminescence, steady‐state absorption, and femtosecond transient absorption spectroscopy, reaching a maximum pressure of 3.38 GPa. The experimental results indicate that CsPbBr3 QDs undergo electronic state (ES) transitions from ES‐I to ES‐II and ES‐II to ES‐III at 0.38 and 1.08 GPa, respectively. Intriguingly, a mixed state of ES‐II and ES‐III is observed within the pressure range of 1.08–1.68 GPa. The pressure‐induced fluorescence quenching in ES‐II is attributed to enhanced defect trapping and reduced radiative recombination. Above 1.68 GPa, fluorescence vanishes entirely, attributed to the complete phase transformation from ES‐II to ES‐III in which radiative recombination becomes non‐existent. Notably, owing to stronger quantum confinement effects, CsPbBr3 QDs exhibit an impressive bandgap tuning range of 0.497 eV from 0 to 2.08 GPa, outperforming nanocrystals by 1.4 times and bulk counterparts by 11.3 times. Furthermore, this work analyzes various carrier dynamics processes in the pressure‐induced bandgap evolution and electron state transitions, and systematically studies the microphysical mechanisms of optical properties in CsPbBr3 QDs under pressure, offering insights for optimizing optical properties and designing novel materials. [ABSTRACT FROM AUTHOR]

Electron transfer (ET) process is considered a substantial factor in influencing the photoelectric conversion efficiency of optoelectronic devices. While pressure has demonstrated effective tune ET, a comprehensive investigation into the mechanisms for both restraining and promoting ET remains elusive. Herein, we have performed measurements using in situ high-pressure steady-state photoluminescence (PL), Raman scattering spectra, and femtosecond transient absorption (fs-TA) spectroscopy on InP/ZnS quantum dot–anthraquinone (InP/ZnS QD-AQ) complexes. The experimental results have demonstrated that the pressure-suppressed ET process in the InP/ZnS QD-AQ complexes arises from both the aggregation-induced emission (AIE) effect of AQ in toluene and the quantum confinement effect of the InP/ZnS QDs. The reduction in the distance between InP/ZnS QD and AQ under pressure emerges as a key factor that promotes the ET process in the InP/ZnS QD-AQ complexes. Furthermore, we observed that the pressure not only enhances the ET process but also suppresses the auger recombination process in liquid phase I of toluene, consequently leading to an enhancement in the photoelectric conversion efficiency. This study contributes to understanding the mechanism of the ultrafast dynamic processes in the pressure-induced QD-receptor complexes, and it has great potential for preparing efficient and stable optoelectronic devices. [ABSTRACT FROM AUTHOR]

The combination of high pressure and severe plastic deformation in the process of high-pressure torsion in a rotational diamond anvil cell (RDAC) produces a variety of important mechanical and chemical effects. In this Review, mechanochemical phenomena that appeared with compression and plastic shear of samples in RDAC have been systematized, which are associated with strain-induced structural changes (SCs) under high pressure and shear, containing phase transitions (PTs) and chemical reactions (CRs). This Review aims to summarize the current phenomena based on the results of multiscale atomic and continuum theory and macroscale modeling. By analyzing and using the advanced phase field theory and simulation, the nano-scale mechanism of phase nucleation induced by plastic strain was studied. The results show that the concentration of the stress tensor near the edge dislocation stacking tip may reduce the nucleation pressure by ten times or more. These results promote the development of a microscopic analysis dynamic equation of strain-induced PTs. On the micro-scale, a simple strain control dynamic kinetics of strain-induced SCs is derived by thermodynamics. On the macro-scale, a macro-model of pressure and strain-induced PTs in RDAC is established based on the finite element method, and it could be used to explain various experimental phenomena. The application of RDAC provides important insights for the coupling of PT and material plastic flow, which is of great significance for optimizing the experimental design and extracting PT parameters of materials, as well as optimizing and controlling PT. [ABSTRACT FROM AUTHOR]

Pressure has an essential role in the control of both the photo-responsive and electrical transport properties of halide perovskites. As a lead-free halide double perovskite material, (NH4)2SeBr6, which avoids the use of a toxic lead element, has become an ideal candidate for application in photovoltaic and photoelectric devices. In this paper, the photoelectric response and electrical transport response properties of (NH4)2SeBr6 have been studied by photocurrent and alternating current impedance spectroscopy measurements under high pressure up to 21.2 GPa, respectively. The current results indicate that in (NH4)2SeBr6, a second photo-responsiveness enhancement re-emerges above 11.2 GPa, after the photocurrent drops from the first maximum at 6.5 GPa and reaches the second maximum at 16.4 GPa. The photoelectric response of (NH4)2SeBr6 in phase II is better than that of phase I, and electron conduction rather than ion conduction plays a dominant role in the whole electrical transportation process under compression. [ABSTRACT FROM AUTHOR]

The magnetic properties and electrical transport behaviors of half-metallic ferromagnet chromium dioxide (CrO2) powders under high pressure have been investigated by in situ electrical resistivity, magneto-resistivity, and Hall-effect measurements. Our results reveal that the Hall coefficient, carrier concentration, and mobility all present discontinuous changes from 11.7 GPa to 14.9 GPa which can be attributed to the second-order structural transition from the rutile-type to CaCl2-type. However, the resistivity decreases monotonically from ambient pressure to 16.5 GPa. This is due to, first, the decreased carrier concentration and the increased carrier mobility canceling the effects of each other on the resistivity; second, according to the calculation results, the bandgap of CrO2 decreased gradually with the pressure, and the bandgaps of the rutile-type phase and the CaCl2-type phase are extremely similar. CrO2 exhibits a linear and negative magnetoresistance under the applied magnetic field (0∼ ± 15 kOe). As the pressure increases, the magnetoresistance remains negative, but it becomes nonlinear and less symmetric, suggesting that pressure has an appreciable impact on the double-exchange mechanism leading to ferromagnetism in CrO2. [ABSTRACT FROM AUTHOR]

Proton-conducting BaZrO3-doped electrolytes are considered as potential high temperature proton conductors due to their high ionic conductivity and electrical efficiency in the operating temperature range of solid oxide fuel cells. However, doping leads to a decrease in grain boundary conductivity and greatly limits its applications. Here, the charge transport properties of sub-micro and nano-BaZrO3 electrolytes were studied by in situ high-pressure impedance measurements and first-principles calculations. Mixed ionic-electronic conduction was found in both samples in the whole pressure range. Pressure-induced negative capacitance in the tetragonal phase of nano-BaZrO3 was observed, which was related to the space charge layer of grain boundaries as well as the electrostrictive strain of grains. The enhanced electrostrictive effect was attributed to the existence of polar nano-domains in nano-BaZrO3. Furthermore, the coincident imaginary part of impedance and modulus peaks on the frequency scale indicated a non-localized carrier conduction in the tetragonal phase of nano-BaZrO3. The grain boundary conductivity of nano-BaZrO3 was enhanced by four orders of magnitude, and the impedance response changed from a constant phase element to an ideal capacitance, which was accompanied by the cubic to tetragonal phase transition. At a switching frequency of 0.1 Hz, the real part of the dielectric function of nano-BaZrO3 increases sharply with frequencies from negative to positive values, exhibiting a plasma-like Drude behavior. Our results provide insight into the optimization and application of BaZrO3-based proton conductors in solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

Pressure has an essential role in the control of both the photo-responsive and electrical transport properties of halide perovskites. As a lead-free halide double perovskite material, (NH4)2SeBr6, which avoids the use of a toxic lead element, has become an ideal candidate for application in photovoltaic and photoelectric devices. In this paper, the photoelectric response and electrical transport response properties of (NH4)2SeBr6 have been studied by photocurrent and alternating current impedance spectroscopy measurements under high pressure up to 21.2 GPa, respectively. The current results indicate that in (NH4)2SeBr6, a second photo-responsiveness enhancement re-emerges above 11.2 GPa, after the photocurrent drops from the first maximum at 6.5 GPa and reaches the second maximum at 16.4 GPa. The photoelectric response of (NH4)2SeBr6 in phase II is better than that of phase I, and electron conduction rather than ion conduction plays a dominant role in the whole electrical transportation process under compression. [ABSTRACT FROM AUTHOR]

ZrSe2, a member of the group-IVB transition metal dichalcogenides, shows favorable performance in optoelectronic applications. Here, the photoelectric properties of ZrSe2 under high pressure have been systematically investigated. At 13.5 GPa, the photocurrent of ZrSe2 increases three orders of magnitude greater than its initial value. Interestingly, above 23.5 GPa, ZrSe2 exhibits a negative photocurrent response, which can be attributed to the photothermal effect caused by pressure-induced metallization. This study demonstrates the critical role of pressure in regulating the optoelectronic properties of layered materials and the potential application of layered ZrSe2 in pressure-responsive optoelectronic devices. [ABSTRACT FROM AUTHOR]

The interface effect is one of the most important factors that strongly affect the structural transformations and the properties of nano-/submicro-crystals under pressure. However, characterization of the granular boundary changes in materials is always challenging. Here, using tetrakaidecahedral Zn2SnO4 microcrystals as an example, we employed alternating current impedance, X-ray diffraction methods and transmission electron microscopy to elucidate the effect of the interface on the structure and electrical transport behavior of the Zn2SnO4 material under pressure. We clearly show that grain refinement of the initial microcrystals into nanocrystals (approximately 5 nm) occurs at above 12.5 GPa and is characterized by an anomalous resistance variation without a structural phase transition. A new phase transition pathway from the cubic to hexagonal structure occurs at approximately 29.8 GPa in Zn2SnO4. The unexpected grain refinement may explain the new structural transition in Zn2SnO4, which is different from the previous theoretical prediction. Our results provide new insights into the link between the structural transition, interface changes and electrical transport properties of Zn2SnO4. [ABSTRACT FROM AUTHOR]

Proton-conducting BaZrO3-doped electrolytes are considered as potential high temperature proton conductors due to their high ionic conductivity and electrical efficiency in the operating temperature range of solid oxide fuel cells. However, doping leads to a decrease in grain boundary conductivity and greatly limits its applications. Here, the charge transport properties of sub-micro and nano-BaZrO3 electrolytes were studied by in situ high-pressure impedance measurements and first-principles calculations. Mixed ionic-electronic conduction was found in both samples in the whole pressure range. Pressure-induced negative capacitance in the tetragonal phase of nano-BaZrO3 was observed, which was related to the space charge layer of grain boundaries as well as the electrostrictive strain of grains. The enhanced electrostrictive effect was attributed to the existence of polar nano-domains in nano-BaZrO3. Furthermore, the coincident imaginary part of impedance and modulus peaks on the frequency scale indicated a non-localized carrier conduction in the tetragonal phase of nano-BaZrO3. The grain boundary conductivity of nano-BaZrO3 was enhanced by four orders of magnitude, and the impedance response changed from a constant phase element to an ideal capacitance, which was accompanied by the cubic to tetragonal phase transition. At a switching frequency of 0.1 Hz, the real part of the dielectric function of nano-BaZrO3 increases sharply with frequencies from negative to positive values, exhibiting a plasma-like Drude behavior. Our results provide insight into the optimization and application of BaZrO3-based proton conductors in solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

This work investigates the impact of pressure on the structural, optical properties, and electronic structure of CsPbBr 3 quantum dots (QDs) using steady-state photoluminescence, steady-state absorption, and femtosecond transient absorption spectroscopy, reaching a maximum pressure of 3.38 GPa. The experimental results indicate that CsPbBr 3 QDs undergo electronic state (ES) transitions from ES-I to ES-II and ES-II to ES-III at 0.38 and 1.08 GPa, respectively. Intriguingly, a mixed state of ES-II and ES-III is observed within the pressure range of 1.08-1.68 GPa. The pressure-induced fluorescence quenching in ES-II is attributed to enhanced defect trapping and reduced radiative recombination. Above 1.68 GPa, fluorescence vanishes entirely, attributed to the complete phase transformation from ES-II to ES-III in which radiative recombination becomes non-existent. Notably, owing to stronger quantum confinement effects, CsPbBr 3 QDs exhibit an impressive bandgap tuning range of 0.497 eV from 0 to 2.08 GPa, outperforming nanocrystals by 1.4 times and bulk counterparts by 11.3 times. Furthermore, this work analyzes various carrier dynamics processes in the pressure-induced bandgap evolution and electron state transitions, and systematically studies the microphysical mechanisms of optical properties in CsPbBr 3 QDs under pressure, offering insights for optimizing optical properties and designing novel materials., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)