RESUMEN
Glassy sulfide materials have been considered as promising candidates for solid-state electrolytes (SSEs) in lithium and sodium metal (LM and SM) batteries. While much of the current research on lithium glassy SSEs (GSSEs) has focused on the pure sulfide binary Li2S + P2S5 system, we have expanded these efforts by examining mixed-glass-former (MGF) compositions which have mixtures of glass formers, such as P and Si, which allow melt-quenching synthesis under ambient pressure and therefore the use of grain-boundary-free SSEs. We have doped these MGF compositions with oxygen to improve the chemical, electrochemical, and thermal properties of these glasses. In this work, we report on the short-range order (SRO), namely atomic-level, structures of Li2S + SiS2 + P2O5 MGF mixed oxy-sulfide glasses and, for the first time, study the critical current density (CCD) of these Si-doped oxy-sulfide GSSEs in LM symmetric cells. The samples were synthesized by planetary ball milling (PBM), and it was observed that a certain minimum milling time was necessary to achieve a final SRO structure. To address the short-circuiting lithium dendrite (LD) problems that were observed in these GSSEs, we demonstrate a simple and novel strategy for these Si-doped oxy-sulfide GSSEs to engineer the LM-GSSE interface by forming an in situ interlayer via heat treatment. Stable cycling to â¼1200 h at a capacity of 2 mAh·cm-2 per discharge/charge cycle under a current density of 1 mA·cm-2 is achieved. These results indicate that these MGF oxy-sulfide GSSEs combined with an optimized interfacial modification may find use in LM, and by extrapolation, SM, batteries.
RESUMEN
To tailor the nanomorphology in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) bulk heterojunction (BHJ). In addition to control; wet P3HT:PC60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions-horizontal (H), tilted (T), and vertical (V)-relative to the plane of the substrate. Surface and bulk characterizations of the field-treated BHJs affirmed that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following the E-field. Using E-field treatment, we achieved favorable morphologies with efficient charge separation, transport, and collection. We improve; (1) the hole mobility values up to 19.4 × 10-4 ± 1.6 × 10-4 cm2 V-1 s-1 and (2) the power conversion efficiency (PCE) of conventional and inverted OPVs up to 2.58 ± 0.02% and 4.1 ± 0.40%, respectively. This E-field approach can serve as a new morphology-tuning technique, which is generally applicable to other polymer-fullerene systems.
RESUMEN
The performance of organic photovoltaic devices is improving steadily and efficiencies have now exceeded 10%. However, the incident solar spectrum still largely remains poorly absorbed. To reduce optical losses, we employed a microlens array (MLA) layer on the side of the glass substrate facing the incident light; this approach does not interfere with the processing of the active-layer. We observed up to 10% enhancement in the short circuit current of poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl}):(6,6)-phenyl C71-butyric acid methyl ester (PTB7:PC71BM) OPV cells. Theoretically and experimentally investigating several MLA dimensions, we found that photocurrent increases with the ratio of the height to the pitch size of MLA. Simulations reveal the enhancement mechanisms: MLA focuses light, and also increases the light path within the active-layer by diffraction. Photocurrent enhancements increase for a polymer system with thinner active-layers, as demonstrated in poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT):PC71BM OPVs with 17% improvement in short circuit current.
