Kesterite Cu2ZnSnS4-xSex Thin Film Solar Cells

Kesterite Cu2ZnSnS4-xSex (CZTS) is a promising thin film photovoltaic (PV) material with low cost and nontoxic constitute as well as decent PV properties, being regarded as a PV technology that is truly compatible with terawatt deployment. The kesterite CZTS thin film solar cell has experienced impressive development since its first report in 1996 with power conversion efficiencies (PCEs) of only 0.66% to current highest value of 13.0%, while the understanding of the material, device physics, and loss mechanism is increasingly demanded. This chapter will review the development history of kesterite technology, present the basic material properties, and summarize the loss mechanism and strategies to tackle these problems to date. This chapter will help researchers have brief background knowledge of kesterite CZTS technology and understand the future direction to further propel this new technology forward.

The Emission of VOCs and CO from Heated Tobacco Products, Electronic Cigarettes, and Conventional Cigarettes, and Their Health Risk

The differences in aerosol composition between new tobacco types (heated tobacco products and electronic cigarettes) and conventional cigarettes have not been systematically studied. In this study, the emissions of volatile organic compounds (VOCs), carbon monoxide (CO), nicotine, and tar from heated tobacco products (HTPs), electronic cigarettes (e-cigarettes) and conventional cigarettes were compared, and their health risks were evaluated by applying the same smoking regime and a loss mechanism of smoking. Twenty VOCs were identified in aerosols from HTPs, 18 VOCs were identified in aerosols from e-cigarettes, and 97 VOCs were identified in aerosols from cigarettes by GC–MS and HPLC analysis. The concentrations of total VOCs (TVOCs) emitted by the three types of tobacco products decreased as follows: e-cigarettes (795.4 mg/100 puffs) > cigarettes (83.29 mg/100 puffs) > HTPs (15.65 mg/100 puffs). The nicotine content was 24.63 ± 2.25 mg/100 puffs for e-cigarettes, 22.94 ± 0.03 mg/100 puffs for cigarettes, and 8.817 ± 0.500 mg/100 puffs for HTPs. When using cigarettes of the same brand, the mass concentrations of VOCs, tar, and CO emitted by HTPs were approximately 81.2%, 95.9%, and 97.5%, respectively, lower than the amounts emitted by cigarettes. The health risk results demonstrated that the noncarcinogenic risk of the three types of tobacco products decreased as follows: cigarettes (3609.05) > HTPs (2449.70) > acceptable level (1) > e-cigarettes (0.91). The lifetime cancer risk (LCR) decreased as follows: cigarettes (2.99 × 10−4) > HTPs (9.92 × 10−5) > e-cigarettes (4.80 × 10−5) > acceptable level (10−6). In general, HTPs and e-cigarettes were less harmful than cigarettes when the emission of VOCs and CO was considered.

Production and loss of O2(1Δg) at atmospheric pressure using microwave-driven microplasmas

We have used arrays of microwave-generated microplasmas operating at atmospheric pressure to generate high concentrations of singlet molecular oxygen, O2(1Δg), which is of interest for biomedical applications. The discharge is sustained by a pair of microstrip-based microwave resonator arrays which force helium/oxygen gas mixtures through a narrow plasma channel. We have demonstrated the efficacy of both NO and less-hazardous N2O additives for suppression of ozone and associated enhancement of the O2(1Δg) yield. Quenching of O2(1Δg) by ozone is sufficiently suppressed such that quenching by ground state molecular oxygen becomes the dominant loss mechanism in the post-discharge outflow. We verified the absence of other significant gas-phase quenching mechanisms by measuring the O2(1Δg) decay along a quartz flow tube. These measurements indicated a first-order rate constant of (1.2 ± 0.3) × 10-24 m3 s−1, slightly slower than but consistent with prior measurements of singlet oxygen quenching on ground state oxygen. The discharge-initiated reaction mechanisms and data analysis are discussed in terms of a chemical kinetics model of the system.

Self-Absorption Analysis of Perovskite-Based Luminescent Solar Concentrators

Luminescent solar concentrators (LSCs) are considered promising in their application as building-integrated photovoltaics (BIPVs). However, they suffer from low performance, especially in large-area devices. One of the key issues is the self-absorption of the luminophores. In this report, we focus on the study of self-absorption in perovskite-based LSCs. Perovskite nanocrystals (NCs) are emerging luminophores for LSCs. Studying the self-absorption of perovskite NCs is beneficial to understanding fundamental photon transport properties in perovskite-based LSCs. We analyzed and quantified self-absorption properties of perovskite NCs in an LSC with the dimensions of 6 in × 6 in × 1/4 in (152.4 mm × 152.4 mm × 6.35 mm) using three approaches (i.e., limited illumination, laser excitation, and regional measurements). The results showed that a significant number of self-absorption events occurred within a distance of 2 in (50.8 mm), and the photo surface escape due to the repeated self-absorption was the dominant energy loss mechanism.

Runoff Characteristics and Soil Loss Mechanism in the Weathered Granite Area under Simulated Rainfall

Soils developed from the parent materials of highly weathered granite are particularly susceptible to soil erosion. Therefore, it is of great significance to conduct in-depth research on runoff characteristics and soil loss mechanisms in weathered granite areas. Using the weathered granite area in the hilly region of southeastern China as the research object, we conducted indoor artificial rainfall simulation experiments involving three slope steepnesses (SSs), 8°, 15°, and 25°, and five rainfall intensities (RIs), 0.5, 1.0, 1.5, 2.0, and 2.5 mm/min. The results showed that sediment load (SL) has positively linear relationships with mean runoff velocity (V), Reynolds number (Re), Froude number (Fr), shear stress (τ), and stream power (w). The eroded sediment was principally composed of silt and clay that accounted for 65.41–73.41% of the total SL. There was a boundary point at 0.02 mm for the particle size distribution (PSD) of the eroded sediment. The enrichment ratio (Er) of sand-grained particles (0.02–2 mm) ranged from approximately 0.45 to 0.65, while the Er of fine-grained particles (<0.02 mm) ranged from approximately 1.37 to 1.80. These results increase our understanding of the relationships among RI, SS, runoff, and soil losses from weathered granite hillslopes, particularly the relationships between different hydraulic parameters and sediment size characteristics.

Fabrication of Electrospun Ni0.5Zn0.5Fe2O4 Nanofibers Using Polyvinyl Pyrrolidone Precursors and Electromagnetic Wave Absorption Performance Improvement

Ni0.5Zn0.5Fe2O4 nanofibers with an average diameter of 133.56 ± 12.73 nm were fabricated by electrospinning and calcination. According to our thermogravimetric—differential thermal analysis and X-ray diffraction results, the calcination temperature was 650 °C. The microstructure, crystal structure, and chemical composition of the nanofibers were observed using field-emission scanning electron, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Commercial particle samples and samples containing 10 wt% and 20 wt% nanofibers were fabricated, and the electromagnetic properties were analyzed with a vector network analyzer and a 7.00 mm coaxial waveguide. Regardless of the nanofiber content, Ni0.5Zn0.5Fe2O4 was dominantly affected by the magnetic loss mechanism. Calculation of the return loss based on the transmission line theory confirmed that the electromagnetic wave return loss was improved up to −59.66 dB at 2.75 GHz as the nanofiber content increased. The absorber of mixed compositions with Ni0.5Zn0.5Fe2O4 nanofibers showed better microwave absorption performance. It will be able to enhance the performance of commercial electromagnetic wave absorbers of various types such as paints and panels.

Resonant wave-filament interactions as a loss mechanism for HHFW heating and current drive

Perkins et al. PRL 2012 [1] reported unexpected power losses during High Harmonic Fast Wave (HHFW) heating and current drive in NSTX. Recently, Tierens et al [2] proposed that these losses may be attributable to surface waves on field-aligned plasma filaments, which carry power along the filaments, to be lost at the endpoints where the filaments intersect the limiters. In this work, we show that there is indeed a resonant loss mechanism associated with the excitation of these surface waves, and derive an analytic expression for the power lost to surface wave modes at each filament.