Nanowerk December 23, 2024 3D buckling makes stretchability possible in devices but, when applied to piezoelectric devices due to the uneven distribution of internal strain during deformation. When strains with opposite directions simultaneously affect piezoelectric materials, the electric output can decrease due to cancellation. Researchers in the Republic of Korea developed an electrode design tailored to the direction of strain and a circuit configuration that prevented electric output cancellation. These designs provided stretchability to piezoelectric nanogenerators (PENGs) and minimized electric output loss. Using an inorganic piezoelectric material with a high piezoelectric coefficient, they demonstrated the dynamics of energy harvesting. In […]
Tag Archives: Energy
Cooling with light: Exploring optical cooling in semiconductor quantum dots
Phys.org November 26, 2024 Highly efficient anti-Stokes (AS) photoluminescence (PL) is observed from halide perovskite quantum dots (QDs) due to their strong electron–phonon interactions. However, the PL quantum efficiency in QDs is primarily dominated by multiparticle nonradiative Auger recombination processes under intense photoexcitation, which impose limits on the optical cooling gain. Researchers in Japan investigated the Auger recombination of dot-in-crystal perovskites and quantitatively estimated the maximum optical cooling gain and the corresponding excitation intensity. Their optical cooling experiments demonstrated a maximum photo cooling of approximately 9 K from room temperature confirming that increasing the excitation intensity led to a transition […]
New nanomaterials could boost hydrogen production for clean energy
Phys.org August 5, 2024 Nanosizing confers unique functions in materials such as graphene and quantum dots. An international team of researchers (UK, China) described two nanoscale-covalent organic frameworks (nano-COFs) that exhibited exceptionally high activity for photocatalytic hydrogen production that resulted from their size and morphology. Compared to bulk analogues, the downsizing of COFs crystals using surfactants provided greatly improved water dispersibility and light-harvesting properties. The nano-COFs showed high hydrogen evolution rate. They observed a reverse concentration-dependent photocatalytic phenomenon where a higher photocatalytic activity was found at a lower catalyst concentration, and the materials showed a molecule-like excitonic nature, a function […]
Stacking molecules like plates improves organic solar device performance
Phys.org August 6, 2024 To further improve the efficiency of optoelectronic devices to convert sun light into electricity, researchers in Japan investigated the relationship between aggregation and Exciton binding energy (Eb) and tetraphenylethylene (TPE). Although theoretical calculations and physical measurements in solution showed no apparent differences between DBC-RD and TPE-RD, the pristine films incorporating these molecules showed significantly different levels of electron affinity, ionization potential, and optical gap. Also, DBC-RD had a smaller Eb value compared with that of TPE-RD. However, these molecules showed similar Eb values under dispersed conditions, suggesting that the decreased Eb of DBC-RD in pristine film […]
MXenes for energy storage: Chemical imaging more than just surface deep
Phys.org June 17, 2024 Due to their versatile tunable properties MXene flakes are used as electrodes in lithium-ion batteries and diverse applications, from energy storage to electromagnetic shielding. However, the local distribution of surface functional groups over single flakes and within few- or multilayered flakes remains unclear. An international team of researchers (Germany, France) introduced scanning X-ray microscopy (SXM) with simultaneous transmission and electron yield detection of individual MXene flakes enabling multimodal nanoscale chemical imaging with bulk and surface sensitivity, respectively. The Ti chemical bonding environment is found to significantly vary between few-layered and multilayered MXenes. Simultaneous bulk and surface […]
Controlling ion transport for a blue energy future: Research highlights the potential of nanopore membranes
Phys.org May 30, 2024 Nanofluidic channels in a membrane represent a promising avenue for harnessing blue energy from salinity gradients. Surface charge is a central player in the osmotic energy conversion process. An international team of researchers (Japan, Italy) present a field-effect approach for in situ manipulation of the ion selectivity in a nanopore. Application of voltage to a surround-gate electrode allowed precise adjustment of the surface charge density at the pore wall. Leveraging the gating control, they demonstrated perm selectivity turnover to enhanced cation selective transport in multipore membranes, resulting in a 6-fold increase in the energy conversion efficiency. […]
Carbon-capture batteries developed to store renewable energy, help climate
Science Daily May 15, 2024 To investigate the deactivation and reactivation mechanisms of the aqueous Na–CO2 battery during extended cycling, researchers at Oak Ridge National Laboratory designed the cathode to include non-precious intermetallic catalysts. As the cell underwent repeated cycles, the voltage polarization during discharge progressively rose, eventually led to the cell’s deactivation and formation of decomposition products clogging the electrode surface. Results obtained from comprehensive characterization techniques provided insight into the decomposition products. They showed an electrochemical approach for regeneration of the aqueous cells. According to the researchers their findings provide a path toward creating long-duration systems with self-healing […]
Researchers create materials with unique combination of stiffness, thermal insulation
Phys.org May 29, 2024 Thermal conductivity and elastic modulus are usually positively correlated in soft materials. A team of researchers in the US (North Carolina State University, Texas A&M University) have shown anomalous correlations of thermal conductivity and elastic modulus in 2D hybrid organic–inorganic perovskites (HOIP) by engineering the molecular interactions between organic cations. By replacing conventional alkyl–alkyl and aryl–aryl type organic interactions with mixed alkyl–aryl interactions, they observed an enhancement in elastic modulus with a reduction in thermal conductivity. The anomalous dependence provided a route to engineer thermal conductivity and elastic modulus independently and a guideline to search for […]
Researchers determine structure of new metal tellurate material with potential uses in solar energy and more
Phys.org April 3, 2024 An international team of researchers (Austria, Sweden, Canada, Finland) grew crystals of CoTeO4 crystals by the application of chemical vapor transport reactions in closed silica ampoules, starting from polycrystalline material in a temperature gradient with TeCl4 as transport agent. Crystal structure analysis of CoTeO4 showed noticeable improvement over the statistical significance and accuracy of the previously reported structural model. CoTeO4 did not undergo a structural phase transition upon heating, but decomposed stepwise (Co2Te3O8 as intermediate phase) to Co3TeO6 as the only crystalline phase stable above 770 °C. Temperature-dependent magnetic susceptibility and dielectric measurements suggested antiferromagnetic ordering […]
A solar cell you can bend and soak in water
RIKEN Research March 27, 2024 Waterproofing ultra flexible organic photovoltaics without compromising mechanical flexibility and conformability remains challenging. An international team of researchers (Japan, USA – Georgia Institute of Technology) demonstrated waterproof and ultra flexible organic photovoltaics through the in-situ growth of a hole-transporting layer to strengthen interface adhesion between the active layer and anode by depositing silver electrode directly on top of the active layers, followed by thermal annealing treatment. The in-situ grown hole-transporting layer exhibited higher thermodynamic adhesion between the active layers, resulting in better waterproof. The 3 μm-thick organic photovoltaics retained 89% and 96% of their pristine performance […]