Research Progress of Alkali Doped Cu(In,Ga)Se2 Thin Film Solar Cells

: Cu(In,Ga)Se2 (CIGS) thin film solar cell has the advantages of high efficiency, good working stability and low manufacturing cost, which is the most promising thin film solar cell. Currently, the efficiency of CIGS thin film cell has reached 23.35% by doping alkali elements. This review summarized the current status of doping alkali elements on flexible CIGS thin film solar cells with a focus on recent advancements intended for higher efficiency and novel applications. First, the structure of CIGS thin film cell was introduced. According to the structural characteristics of CIGS cells, different doping methods of alkali metals were summarized. Then, the recent developments and trends of research in doping methods of alkali elements within the last years were reviewed, and the effect of different alkali elements on CIGS efficiency were emphasized. Finally, the challenges and opportunities of alkali doping CIGS solar cell were prospected.

Bio-Crude Production Improvement during Hydrothermal Liquefaction of Biopulp by Simultaneous Application of Alkali Catalysts and Aqueous Phase Recirculation

This study focuses on the valorization of the organic fraction of municipal solid waste (biopulp) by hydrothermal liquefaction. Thereby, homogeneous alkali catalysts (KOH, NaOH, K2CO3, and Na2CO3) and a residual aqueous phase recirculation methodology were mutually employed to enhance the bio-crude yield and energy efficiency of a sub-critical hydrothermal conversion (350 °C, 15–20 Mpa, 15 min). Interestingly, single recirculation of the concentrated aqueous phase positively increased the bio-crude yield in all cases, while the higher heating value (HHV) of the bio-crudes slightly dropped. Compared to the non-catalytic experiment, K2CO3 and Na2CO3 effectively increased the bio-crude yield by 14 and 7.3%, respectively. However, KOH and NaOH showed a negative variation in the bio-crude yield. The highest bio-crude yield (37.5 wt.%) and energy recovery (ER) (59.4%) were achieved when K2CO3 and concentrated aqueous phase recirculation were simultaneously applied to the process. The inorganics distribution results obtained by ICP reveal the tendency of the alkali elements to settle into the aqueous phase, which, if recovered, can potentially boost the circularity of the HTL process. Therefore, wise selection of the alkali catalyst along with aqueous phase recirculation assists hydrothermal liquefaction in green biofuel production and environmentally friendly valorization of biopulp.

Compositional Variation and Color Diversity of Glass Beads from a 4th Century Tomb Complex in Korea

This study investigated the chemical compositions and color diversity of various colored glass beads excavated from the 4th century Suchonri site in Korea. The results reveal that the compositions of the coloring materials and stabilizers contain black or white impurities, and there are clear boundaries in the weathered surfaces within the glass beads. The weathered side turned brown, the amounts of Na and K are greater, and there is a decrease in alkali elements. The fragments in blue-green beads from tomb No. 11 were identified as potash glass, whereas the rest of the samples were soda glass. Analysis of the coloration elements identified Fe and Cu in all glass beads, and it was estimated that both elements resulted in a green color. Fe was predicted to cause a brown color. The results of the study may be used not only for scientific interpretation of the relics from the Suchonri tomb complex but also as archaeological evidence that may contribute to the material characterization of the ancient glass from the Korean peninsula.

Experimental constraints on the onset of planetesimal melting, the formation of primitive achondrites and the distribution of alkali elements in the solar nebula

<p>In this presentation, we will summarize the conclusions of three recent articles [1-3] describing partial melting experiments of ordinary and carbonaceous synthetic chondrites (H, LL, CI, CM and CV). The experiments highlight the role of alkali elements on the melting processes of chondritic planetesimals and provide insights into the distribution of “moderately volatile elements” in the early solar system. They were performed at 2–13 MPa (CO pressure) in a Molybdenum-Hafnium Carbide Pressure Vessel. This approach prevented the loss of alkali elements during experiments, a common limitation of previous studies using gas-mixing furnaces.</p> <p>Alkali-rich planetesimals, similar in composition to CI, H and LL chondrites, started to melt at low temperature (1040 ºC) and produced silicate melts with high alkali, SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> contents [1], similar in composition to “trachyandesite achondrites” such as GRA 06128 [4] and ALM-A [5]. In addition, the main groups of primitive achondrites (i.e., brachinites, acapulcoites-lodranites and ureilites), which represent mantle residues, all produced similar low-degree melts (<15 wt.%) rich in SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub> and alkalis that were extracted from the mantle of the different parent bodies [2].</p> <p>Ureilites (>550 samples), represent the residual mantle of a planetesimal that was catastrophically disrupted and quenched while in the process of melting [3]. Our experiments show that the Ureilite Parent Body (UPB) produced a total of 16-24 wt.% silicate melt as small increments (< 5%). Following the extraction of melts rich in SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub> and alkalis, the residual mantle produced melts poor in alkalis but rich in CaO. The sampled portion of the UPB reached temperatures as high as 1300 ºC, but the rapid extraction of silicate melts preserved primordial heterogeneities in O, C and Cr isotopes as well as in intrinsic fO<sub>2</sub>.</p> <p>Trachyandesite achondrites, ureilites and other major groups of primitive achondrites were all derived from planetesimals that were initially rich in alkali elements (i.e., not depleted relative to the Sun’s photosphere). They all display nucleosynthetic anomalies characteristic of the inner solar system. Therefore, the depletion of alkalis in other meteorite parent bodies of the inner solar system (e.g., Vesta) likely results from processes that occurred during partial melting. Similarly, the depletion of alkalis in terrestrial planets could result from a secondary loss of alkalis associated with partial melting of the planets building blocks, rather than from the incomplete condensation of the solar nebula.</p> <p>References:</p> <p>[1] Collinet and Grove (2020a), GCA, https://doi.org/10.1016/j.gca.2020.03.005, [2] Collinet and Grove (2020b), GCA, https://doi.org/10.1016/j.gca.2020.03.004, [3] Collinet and Grove (2020c), MAPS, https://doi.org/10.1111/maps.13471, [4] Day et al., (2009), Nature, https://doi.org/10.1038/nature07651, [5] Bischoff et al. (2014), PNAS, https://doi.org/10.1073/pnas.1404799111</p>

Long-Term Yield and Quality Performance of Perennial Energy Grasses (Agropyron spp.) on Marginal Land

The cultivation of perennial grasses is one of the most desirable alternatives as energy feedstock, but it is difficult to achieve competitive yields under Mediterranean marginal conditions. The aim of this study was to assess the performance of three cool-season grasses (Agropyron spp.) from an agronomic and energetic point of view by comparing the dry matter (DM) yields, rain use efficiency, chemical composition, and biomass quality over an eight-year period in Spain under marginal rainfed conditions. The tall wheatgrass (Agropyron elongatum (Host) Beauv.) cultivars, Alkar (4.8 Mg DM·ha−1) and Jose (4.7 Mg DM·ha−1), achieved the highest yields. Productions below 0.5 Mg DM·ha−1 were obtained when rainfall was lower than 150 mm between March and June. The biomass obtained from the tested grasses showed relatively high contents of ash, silicon, and alkali elements. Net calorific values ranged between 16.7 and 18.5 MJ·kg−1 db. Differences in the composition among species and cultivars are not likely to affect their combustion behavior from a practical point of view. The ash content, as well as the concentrations of K, S, Na, and Cl, tended to decrease over the years. The results offered would be very useful for the implementation of this type of crop in marginal land.

Chemical Variations in Hydrothermal White Mica Across the Highland Valley Porphyry Cu-Mo District, British Columbia, Canada

Hydrothermal white mica in the Highland Valley district, British Columbia, is present in high-temperature alteration assemblages in early halo veins and in intermediate-temperature sericitic alteration assemblages in D-type veins. Pale-gray white micas characterize early halo veins in the Valley and Bethsaida zone porphyry Cu-Mo deposits, whereas pale-green white micas form texturally similar vein halos along the margin of the Valley deposit and at the Alwin vein. White micas in the Bethlehem porphyry Cu-Mo deposit form part of a sericitic alteration assemblage associated with D-type veins that overprinted K-silicate–altered rocks. Cation compositions in white micas indicate phengitic compositions trending toward aluminoceladonite. Pale-gray phengitic white micas intergrown with bornite-chalcopyrite-molybdenite contain elevated Na, indicating higher formation temperatures than those that characterize phengitic white micas formed during hydrolytic alteration. Bethlehem phengitic white micas have cation compositions similar to those of pale-green phengitic white micas at the Valley deposit margin, Bethsaida zone margin, and the Alwin vein. The Al-OH absorption wavelengths in pale-gray phengitic white micas are shorter than in pale-green phengitic white mica or phengitic white mica in the sericitic assemblage. In the phengitic white micas, alkali elements substituting in the interlayered site are positively correlated, whereas higher-valence elements substituting into the octahedral site show a greater variability. The data confirms that hydrothermal white-mica chemistry varies between paragenetic stages of a porphyry Cu deposit and between multiple porphyry deposits in a district.

Behavior of dissolved alkali and alkali-earth elements in a coastal aquifer of Mexico affected by saltwater intrusion

<p>This comprehensive study shows the behavior of major and trace alkali and alkali-earth elements in a coastal sedimentary aquifer of Mexico moderately impacted by saltwater intrusion and anthropogenic activities. For this purpose, the concentrations of major cations (Na<sup>+</sup>, K<sup>+</sup>, Ca<sup>2+</sup> and Mg<sup>2+</sup>), major anions (Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, HCO<sub>3</sub><sup>-</sup>, NO<sub>3</sub><sup>-</sup>) and several alkali and alkali-earth trace elements (Li, Rb, Ba and Sr) were analyzed in all the active groundwater wells of the Todos Santos aquifer, Baja California Sur, northwestern Mexico. The results indicates that the percentage of seawater intruded into the aquifer ranges from 0.2% to 2.7%, with an average of 0.9%. In the recharge areas, groundwater is Ca<sup>2+</sup>–HCO<sub>3</sub><sup>-</sup> type. However, groundwater evolves from Ca<sup>2+</sup>–HCO<sub>3</sub><sup>-</sup> type to Na<sup>+</sup>–Cl<sup>-</sup> type when salinity is increased in the direction of the flow path, suggesting that the intrusion of saltwater is affecting the groundwater chemistry in wells close to the coastline. The excess of Ca<sup>2+</sup> and Mg<sup>2+</sup> over the corresponding anions SO<sub>4</sub><sup>2-</sup> and HCO<sub>3</sub><sup>-</sup> shows that both alkali-earth elements are being replaced by Na<sup>+</sup> in the aquifer matrix. Overall, the excess of all alkali-earth elements over the freshwater-seawater mixing line suggests that this process is extensive to all alkali-earth elements. Overall, the alkali-earth elements Ca<sup>2+</sup>, Mg<sup>2+</sup>, Ba<sup>2+</sup> and Sr<sup>2+</sup> are mobilized from the aquifer matrix during seawater intrusion, whereas the alkali elements Na<sup>+</sup>, K<sup>+</sup> and Rb<sup>+</sup> are removed from solution. This phenomenon can be driven by a cationic exchange process, where alkali-earth element are exchanged by alkali elements in the aquifer matrix. Unlike the other alkali elements, Li is mobilized during saline intrusion, probably also by cationic exchange. The high diffuse NO<sub>3</sub><sup>-</sup> concentrations in wells close to the Todos Santos downtown indicates that nitrates could be provided by anthropogenic activities, specifically by sewage infiltration. This work can be useful as reference for knowing the effect of salinization in the concentration of alkali and alkali-earth trace elements in groundwater of coastal aquifers under sea level rise scenarios driven by climate change.</p>