Electrical and thermal transport properties of synthetic tetrahedrites Cu10TM2Sb4S13 (TM = Mn, Fe, Co, Ni, Zn) and the solid solution Cu12–x Mn x Sb4S13 (0 ≤ x ≤ 2) have been studied in the context of thermoelectric performance. Among these materials, the parent compound Cu12Sb4S13 exhibits the highest power factor, which is primarily derived from a high electrical conductivity. All substituted derivatives display a significant and uniform reduction in thermal conductivity. Within the TM series, the Mn-substituted sample displays the highest ZT (0.8 at 575 K). Changing the Mn concentration to Cu11MnSb4S13 produces the highest ZT, i.e., 1.13 at 575 K. The relatively high value derives from a favorable balance of low thermal conductivity and a relatively high power factor.

In this Letter, we described a solution-processed indium-gallium-zinc oxide thin-film transistors (TFTs) with a solution-processed aluminum oxide phosphate gate dielectric, fabricated at a maximum annealing temperature under 350 °C to be applicable to conventional fabrication process of flat-panel displays (FPDs). The solution-processed TFTs exhibited competitive device characteristics under 350 °C, including a field-effect mobility of 4.50 cm2/Vs, an on-to-off current ratio of ∼109, a threshold voltage of 2.34 V, and a subthreshold gate swing of 0.46 V/dec, making them applicable to the future backplane of FPDs.

used to guide the selection and design of new absorbers using computational techniques. This metric captures the leading physics of absorption relevant to PV efficiency, and it improves upon the simple Shockley-Queisser bandgap model [ 7 ] by considering the full absorption spectrum of the absorber. Hence, SLME should be effective for guiding the selection and design of new ultrathin absorber materials for study and use in drift-aided cells. We have applied the SLME approach to the analysis of all ternary chalcogenides containing Cu, including materials in the system Cu-V-VI. [ 9 ] Several materials were found to exhibit SLME values much higher than those of conventional thin-fi lm absorbers.Subsequently, two general principles were formulated to guide the selection and design of new high-performance absorbers. [ 9 ] In the fi rst case, structural isolation of a Group-V atom in its 5+ oxidation state, e.g., Sb 5+ , within a Cu-rich matrix leads to a narrow Group-V-derived s-orbital band at the conduction band minimum (CBM). In combination with a narrow Cu d band at the valence band maximum (VBM), a high joint density of states and a high absorption coeffi cient ensue. In the second case, if the Group-V atom exists in the lower 3+ oxidation state, e.g., Sb 3+ , it adopts an ns 2 valence electron confi guration. In this 3+ oxidation state, highly asymmetric coordination environments can lead to long distances between the Group-V atoms, resulting in fl at bands and attendant high joint densities of states. These features contribute to an abrupt absorption onset and a high absorption coeffi cient. Strong absorption is reinforced by the parity-allowed nature of the electric-dipole V s or Cu d → V p transition. Hence, the second design principle focuses on structurally isolating the lower oxidation state Group-V element in a semiconducting matrix. Results and DiscussionThese considerations have led us to consider the mineral tetrahedrite, i.e., Cu 12 Sb 4 S 13 , as the basis for a new family of solar absorbers. This material was not revealed as a candidate in the initial SLME search [ 9 ] of Cu-V-VI materials because it was computed to have a zero bandgap, i.e., it is a metal and not a semiconductor. This metallic behavior can readily be appreciated by considering the mixed oxidation-state nature of Cu 12 Sb 4 S 13 . A mixture of formal oxidation states Cu 2+ (d 9 ) and Cu 1+ (d 10 ) is required for charge neutrality, i.e., 10 of the 12 Cu atoms in the chemical formula Cu 12 Sb 4 S 13 are monovalent, while the remaining two Cu atoms are divalent. An incompletely fi lled d-valence band is expected to give rise to the observed degenerate (metallic) behavior, [10][11][12][13] consistent with the Computational inverse design and consequent experimental results allow for the identifi cation of new tetrahedrite-mineral compositions as promising absorber candidates in drift-based thin-fi lm solar cells. In device simulations, cell effi ciencies above 20% are modeled with absorber layers as thin as 250 nm. These new compositio...

To realize the fundamental limits of photovoltaic device efficiency, solar absorbers must exhibit strong absorption and abrupt absorption onsets. Ideally, onsets to maximum absorption (α > 105 cm–1) occur over a few tenths of an electronvolt. First-principles calculations predict CuTaS3 represents a potentially new class of materials with such absorption characteristics. Narrow metallic d bands in both the initial and final states present high joint densities of states and, therefore, strong absorption. Specifically, a mixture of metal d (Cu1+, d 10) and S p characterizes states near the valence band maximum, and metal d (Ta5+, d 0) dominates near the conduction band minimum. Optical absorption measurements on thin films confirm the abrupt onset to strong absorption α > 105 cm–1 at E g + 0.4 eV (E g = 1.0 eV). Theoretical CuTaS3 solar cell efficiency is predicted to be 28% for a 300 nm film based on the metric of spectroscopic limited maximum efficiency, which exceeds that of CuInSe2. This sulfide may offer new opportunities to discover and develop a new class of mixed d-element solar absorbers.

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Normal heating, ventilation, and air conditioning (HVAC) systems typically use high-efficiency particulate air (HEPA) filters, which can filter dust, various pollutants, and even bacteria and viruses from indoor air. However, since HEPA filters cannot not clean themselves and due to the nature of these microbes which can survive for long periods of time, changing these filters improperly could transmit pathogenic bacteria or viruses, and could even lead to new infections. This study indicated that these manufactured Solid Oxygen-purifying (SOP) filters have the potential to self-disinfect, filter, and inactivate aerosolized viruses. MS2 bacteriophage was used as a model virus in two different experiments. The first experiment involved aerosolization of the virus, while the second were a higher viral load using a soaking method. The SOP filters inactivated up to 99.8% of the virus particles in both experiments, provided that the density of the SOP filter was high. Thus, SOP filters could self-clean, which led to protection against airborne and aerosolized viruses by inactivating them on contact. Furthermore, SOP filters could be potentially use or addition in HVAC systems and face masks to prevent the transmission of airborne and aerosolized viruses.

Use of diesel locomotives in transport is gradually decreasing due to electrification and the introduction of high-speed electric rail. However, in Korea, up to 30% of the transportation of passengers and cargo still uses diesel locomotives and diesel vehicles. Many studies have shown that exhaust gas from diesel locomotives poses a threat to human health. This study examined the characteristics of particulate matter (PM), nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons in diesel locomotive engine exhaust. Emission concentrations were evaluated and compared with the existing regulations. In the case of PM and NOx, emission concentrations increased as engine output increased. High concentrations of CO were detected at engine start and acceleration, while hydrocarbons showed weakly increased concentrations regardless of engine power. Based on fuel consumption and engine power, the emission patterns of PM and gaseous substances observed in this study were slightly higher than the U.S. Environmental Protection Agency Tier standard and the Korean emission standard. Continuous monitoring and management of emissions from diesel locomotives are required to comply with emission standards. The findings of this study revealed that emission factors varied based on fuel consumption, engine power, and actual driving patterns. For the first time, a portable emission measurement system (PEMS), normally used to measure exhaust gas from diesel vehicles, was used to measure exhaust gas from diesel locomotives, and the data acquired were compared with previous results. This study is meaningful as the first example of measuring the exhaust gas concentration by connecting a PEMS to a diesel locomotive, and in the future, a study to measure driving characteristics and exhaust gas using a PEMS should be conducted.

Gravel is used in railway infrastructure to reduce environmental impacts and noise, but gravel on tracks must be replaced continuously because it deforms due to wear and weathering. It is therefore necessary to review the entire railroad life cycle. In this study, an unmanned aerial vehicle (UAV) was used to measure resuspended dust over a wide area. The dust was generated from transport movements in relation to the operation of a quarry, which represents the first stage of the railway life cycle. The dust was measured at Gangwon-do quarry using a Sniffer4D module, which can provide measurements at 1 s intervals through a light scattering method and has high reliability (R2 = 0.95 for PM2.5, R2 = 0.88 for PM10). The hourly generation of fugitive dust was calculated as 2937.5 g/h for PM2.5 and 4293.2 g/h for PM10. The social cost of dust generation was calculated as KRW 36.59 billion. The amount of dust generated per hour at the quarry was ~12 times greater than that generated by the operation of a regulator as a maintenance vehicle, with the largest amount of fugitive dust generated by the washing-type vehicle. This is the first study to measure the amount of fugitive dust generated in real time at 1 s intervals by monitoring the first stage of the railroad life cycle over a wide area using a Sniffer4D module attached to a UAV. This method can be replicated for use in various studies.