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In this work, we present a novel unidirectional transducer design for frequency scaling aluminum nitride (AlN)-based radio frequency (RF) microsystems. The proposed thickness-field-excited single-phase unidirectional transducers (TFE-SPUDT) adopt 5/16 wavelength electrodes and, thus, enable efficient piezoelectric transduction with better frequency scalability. The design space of the TFE-SPUDT is theoretically explored and validated using the acoustic delay line (ADL) testbeds. The ADL testbeds with a large feature size of ${3}~\mu \text{m}$ show a center frequency of 1 GHz, a minimum insertion loss (IL) of 4.9 dB, and a fractional bandwidth (FBW) of 5.3%, significantly surpassing the IL and frequency scalability of the previously reported AlN transducers. The design approach can potentially contribute to various AlN-based RF microsystems for signal processing, physical sensing, optomechanical interaction, and quantum acoustic applications, and are readily extendable to other piezoelectric platforms. [ABSTRACT FROM AUTHOR]

As a low-cost, non-volatile, highly polar and chemically stable solvent, sulfolane has a high implementation potential for electroplating in organic media. This is the first report of the electrodeposition of silicon from sulfolane-based electrolytes. Voltammetric and chronoamperometric techniques, coupled with a quartz crystal microbalance, have been used to perform and characterize the process. Resonance frequency, f , damping, w , and apparent molar mass, M app are used as sensitive parameters for the evaluation of the silicon layer formation. Si electrodeposition displays a strong dependence on the applied potential. Close to theoretical values for M app and minimal w are observed at low deposition overpotentials, which allow an in situ quantitative mass evaluation. At higher overpotentials the process efficiency decreases due to simultaneous electrolyte decomposition. The electrodeposition of elemental Si (approx. 60% of the entire Si content) is evidenced by X-ray photoelectron spectroscopy. Additionally, the formation of a binary metal compound with the Cu substrate might be a key factor in the very good adhesion and mechanical stability of the layer. • Silicon layers are deposited from a sulfolane-based electrolyte. • EQCM measurements support the suitability of this electrolyte for Si deposition. • Low deposition overpotentials correlate with low roughness and reduced contamination. • The apparent molar mass increases with overpotential. [ABSTRACT FROM AUTHOR]

We present a group of low-loss Lamb mode acoustic delay lines in an aluminum nitride (AlN) thin film. The low-loss acoustic delay lines are enabled by the thickness-field-excited single-phase unidirectional transducers. The fabricated miniature acoustic delay lines show a fractional bandwidth of 4.5%, a minimum insertion loss of 5.9 dB, outperforming the previously reported aluminum nitride delay platforms. The demonstrated delay ranges from 105 ns to 165 ns with center frequencies from 175 MHz to 255 MHz. The design approach and the significantly lower insertion loss described herein are expected to open new horizons for hybridized signal processing based on AlN and CMOS. [2019-0094] [ABSTRACT FROM AUTHOR]

[Display omitted] • electrochemically formed porous Cu is applied in high-performance binder-free silicon anodes • porous Cu enhances the mechanical and electrochemical stability of electrodeposited Si • Si deposited in sulfolane electrolyte displays improved performance as anode for Li ion battery In this work, an electrochemically formed porous Cu current collector (p-Cu) is utilized for the development of a high-performance binder-free silicon anode. Two electrolyte compositions based on sulfolane (SL) and [BMP][TFSI] ionic liquid (IL) are implemented for silicon deposition. The electrochemical experiments confirm the advantages of applying the p-Cu structure in terms of specific capacity, rate capability, and long-term cycling, where the best electrochemical properties have been observed for the Si deposited from SL electrolyte. The Si-based p-Cu anodes formed in SL display stable 2500 mAh g−1 reversible capacity during the first 250 cycles and promising capacity retention. Compared to this result, the cycling performance of the same type of material deposited on flat Cu foil (f-Cu) showed significantly reduced capacity (1400 mAh g−1) and inferior cycling performance. The positive effect can be attributed to the improved mechanical stability of the active material and accelerated ionic transport in the porous structure of the anode. The improved functional properties of the electrochemically deposited Si from SL electrolyte in p-Cu samples compared to those obtained in IL can be ascribed to differences in the chemical composition. While the layers deposited in SL electrolyte involve Si domains incorporated in a matrix containing C and O that offer high mechanical stability, the Si material obtained in IL is additionally influenced by N and F chemical species, resulting from active IL decomposition. These differences in the chemical surrounding of the Si domains are the primary reason for the inferior electrochemical performance of the material deposited from [BMP][TFSI] electrolyte. XPS analysis shows that the initial composition of the as deposited layers, containing a considerable amount of elemental Si, is changed after lithiation and that the electrochemical activity of the anode is governed by switching between the intermediate redox states of Si, where the carbon-oxygen matrix is also involved. [ABSTRACT FROM AUTHOR]

• Nucleation and growth of silicon is studied in room-temperature ionic liquid. • Kinetic model, accounting propagation and overlap of diffusion zones is applied. • The nucleation process has a progressive behavior at low overpotentials. • Instantaneous character of nucleation with the applied overpotential is observed. The electrochemical nucleation and growth of silicon on a vitreous carbon substrate in 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide [BMP][TFSI] is investigated by interpreting potentiostatic current transients. Theoretical model for three-dimensional nucleation, accounting for propagation and overlap of diffusion zones is applied for quantitative characterization of the process. In addition to the established methodology of current maxima analysis in dimensionless coordinates our approach involves interpretation of the entire current transient by a non-linear fitting procedure. The initial stages of the Si phase formation display an instantaneous behavior, showing a tendency for more progressive character with decreasing the applied overpotential. The results attained by analysis of the current transients are confirmed by scanning electron microscopy (SEM). The chemical composition of the deposit is determined by X-Ray Photoelectron Spectroscopy (XPS). [ABSTRACT FROM AUTHOR]

In this work, we present the low-loss acoustic delay lines (ADLs) at 5 GHz, using the first-order antisymmetric (A1) mode in 128° Y-cut lithium niobate thin films. The ADLs use a single-phase unidirectional transducer (SPUDT) design with a feature size of quarter acoustic wavelength. The design space is analytically explored and experimentally validated. The fabricated miniature A1 ADLs with a feature size of $0.45~\mu \text{m}$ show a high operating frequency at 5.4 GHz, a minimum insertion loss (IL) of 3 dB, a fractional bandwidth (FBW) of 1.6%, and a small footprint of 0.0074 mm2. The low IL and high operating frequency have significantly surpassed the state-of-the-art performance of ADLs. The propagation characteristics of A1 acoustic waves have also been extracted. The demonstrated designs can lead to low-loss and high-frequency transversal filters for future 5G applications in the sub-6-GHz bands. [ABSTRACT FROM AUTHOR]

In this work, we present a new paradigm for enabling gigahertz higher-order Lamb wave acoustic devices using complementarily oriented piezoelectric (COP) thin films. Acoustic characteristics are first theoretically explored with COP lithium niobate (LiNbO3) thin films, showing their excellent frequency scalability, low loss, and high electromechanical coupling ($k^{2}$). Acoustic resonators and delay lines are then designed and implemented, targeting efficient excitation of higher-order Lamb waves with record-breaking low loss. The fabricated resonator shows a $2^{\mathbf {nd}}$ -order symmetric (S2) resonance at 3.05 GHz with a high quality factor ($Q$) of 657, and a large $k^{2}$ of 21.5% and a $6^{\mathbf {th}}$ -order symmetric (S6) resonance at 9.05 GHz with a high $Q$ of 636 and a $k^{2}$ of 3.71%, both among the highest demonstrated for higher-order Lamb wave devices. The delay lines show an average insertion loss (IL) of 7.5 dB and the lowest reported propagation loss of 0.014 dB/ $\mu \text{m}$ at 4.4 GHz for S2. Notable acoustic passbands up to 15.1 GHz are identified. Upon further optimizations, the proposed COP platform can lead to gigahertz low-loss wideband acoustic components. [2020-0127] [ABSTRACT FROM AUTHOR]

In this work, we present first-order antisymmetric (A1) mode resonators in 128° Y-cut lithium niobate (LiNbO3) thin films with electromechanical coupling coefficients ($k^{2}$) as large as 46.4%, exceeding the state-of-the-art. The achievable $k^{2}$ of A1 in LiNbO3 substrates of different orientations is first explored, showing X-axis direction in 128° Y-cut LiNbO3 among the optimal combinations. Subsequently, A1 resonators with spurious mode mitigation are designed and fabricated. In addition to the large $k^{2}$ , the implemented devices show a maximum quality factor ($Q$) of 598 at 3.2 GHz. Upon further optimization, the reported platform can potentially deliver a wideband acoustic-only filtering solution in 5G New Radio. [2020–0003] [ABSTRACT FROM AUTHOR]

Following the Paris Agreement, virtually all countries worldwide have committed themselves to undertaking efforts to limit global warming to 1.5 °C. Within the European Union (EU), the recent 'Fit for 55' policy package proposes ambitious greenhouse gas (GHG) mitigation policies for all sectors as part of the EU's contribution to limiting global warming. Yet, it is unclear whether the proposed policies are sufficient for the EU to limit global warming to 1.5 °C and it remains an open policy problem how to translate global temperature targets into sector-specific emission budgets and further into sector-specific policies. Here, we derive GHG budgets for transport in EU27 and obtain GHG mitigation pathways for Europe consistent with 1.5 °C global warming. We do not provide a comprehensive assessment of the 'Fit for 55' transport package but we discuss the main policies for road transport in light of the GHG emission budgets, their level of ambition, and suggest amendments to these policies as well as improvements to the 'Fit for 55' package. Our results suggest that parts of the 'Fit for 55' for transport are still not ambitious enough to align with a 1.5 °C scenario. Key policy insights A Paris-compatible residual carbon budget for EU transport is 10–12 Gt CO2. The budget implies net zero emissions for EU transport by 2044–2048 latest. We find the current 'Fit for 55' proposal for transport is not ambitious enough. A faster phase-out of cars and trucks with combustion engines is required and there is a need for ambitious standards for fast charging e-vehicles. CO2 pricing of transport is not a substitute but a complement to fleet targets. [ABSTRACT FROM AUTHOR]

The Austrian Education Energy Initiative ETSIT has been established as a response to the EU Energy Efficiency Directive and the Austrian Energy Efficiency Act. This paper investigates the energy literacy of its young participants, i.e., 6000 primary and secondary school students altogether, on a cognitive, affective and behavioural level, and it compares the putative energy-saving effectiveness of the workshops to that of conventional energy audits.For the current analysis, data from, 640 students who validly answered an online survey shortly after participating in one of the energy education workshops, and 353 students who validly answered the online survey approximately one year after having participated (overall n = 993) were analysed. The results indicate that ETSIT raises students' energy literacy on a cognitive, affective and behavioural level with about three-quarters of participants claiming they will positively change their energy consumption behaviour in the future as a result of workshop participation. This is true shortly after participation in the workshops, and also at the 1-year follow-up. In its second impact perspective, this paper delivers an innovative attempt to look at education from a cost-benefit analysis. A default formula for energy audits is adopted to quantify the kilowatt hours (and thus emissions and costs) saved through workshop participation. Despite limitations, the surprising results show that such workshops can compete with conventional energy audits, and that education can, in fact, help save money, resources, and, most important of all, the climate. [ABSTRACT FROM AUTHOR]

Branched conjugated architectures should possess the advantage of isotropic charge transport compared to conventional linear conjugated polymers, as for example poly(3-hexylthiophene) (P3HT) which is commonly used in organic solar cells. This contribution investigates the optoelectronic properties of branched poly(thiophene)s p3T and p4T synthesized in a straightforward one-pot procedure by oxidative coupling of branched trithiophene and tetrathiophene monomers with FeCl3. These polymers can be regarded as model systems for ideal amorphous conjugated materials. Optical characterization in solution and in thin films together with cyclic voltammetry data suggests the applicability of these materials for the use in organic solar cell devices. In particular, the HOMO and LUMO levels of the branched polythiophenes are shifted to lower energy values as compared to linear P3HT. Field effect mobilities are in the order of 10–4cm2/(V s). A first optimization of solar cell devices based on the branched polythiophene materials in combination with PCBM as acceptor resulted in efficiencies of 0.6% with open-circuit voltages being about 30% higher (up to 714 mV) than normally found with P3HT. [ABSTRACT FROM AUTHOR]