Synthesis of Quinolino[4,3‐ j]phenanthridines and their Photophysical Characterization

Quinolino[4,3-j]phenanthridines were synthesized from para-terphenyl-2,2′′-diamines, which were obtained by cross-coupling reactions. The diamines were converted into amides and ortho-cyclized to quinolino[4,3-j]phenanthridines using Morgan-Walls reactions. Prolonged reaction times were required in these electrophilic substitution reactions to overcome the respective deactivated intermediates formed after the first ortho fusion. Optophysical properties were determined by UV/Vis and fluorescence spectroscopy and calculated by quantum chemical calculations. The compounds exhibit rather small HOMO/LUMO gaps and a remarkable bathochromic shift of luminescence upon protonation, what makes these compounds promising candidates for optoelectronic applications

Enhanced p-doping and efficiency in organic solar cells using Mg and Pd ions at the HTL/PTB7 interface

This study investigates the application of new hole transport layers (HTLs) integrating magnesium and palladium metals with the organic polymer poly(styrene sulfonate) (PSS) in organic solar cells (OSCs). When used alone, these HTLs exhibited various drawbacks; however, blending them with the benchmark material PEDOT:PSS mitigated these issues and improved efficiency. Ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) measurements provided a detailed understanding of the interfacial energy level alignment, electronic band structure, and band bending at the HTL/PTB7 interface. Single Mg:PSS and Pd:PSS OSCs showed efficiencies of 6.232 and 5.836%, respectively. The relatively low open-circuit voltage (VOC) and fill factor (FF) were attributed to Auger recombination under light intensity. UPS and XPS also indicated that the hole extraction capability of PTB7 was hindered, leading to recombination at the barrier. By blending with PEDOT:PSS, the efficiencies of Mg:PSS and Pd:PSS were improved to 8.356 and 8.303%, respectively. This improvement was due to reduced current leakage, resulting from higher shunt resistance and lower series resistance, as observed in dark current measurements. Additionally, the formation of ohmic contacts at the HTL/PTB7 interface enhanced hole extraction and reduced recombination. This study underscores the potential of mixed organic-metal HTL structures in OSCs to modulate energy band structures, providing insights into the selection of metal-organic combinations for optimizing OSC efficiency and performance

Fast Li+^+ transport kinetics enabled by TiN nanofibers in hybrid polymer-based electrolytes for long-life Li metal batteries

Polymer-based solid-state electrolytes exhibit superior advantages in flexibility, light weight, and large-scale processability, rendering them promising for high-performance solid-state lithium metal batteries (SSLMBs) with enhanced safety. However, challenges like poor structural uniformity, sluggish Li$^+$ transport kinetics, and inferior interface compatibility hinder their practical applications. Herein, a hybrid quasi-solid-state electrolyte (PHLT) composed of a titanium nitride (TiN) fibrous nanofiller and a poly(vinylidene fluoride-co-hexafluoropropylene)/lithium bis(trifluoromethanesulfonyl)imide (PVDF–HFP/LiTFSI) matrix was developed. The inorganic filler could decrease the crystallinity of PVDF–HFP, propel the polar transformation of the polymer, as well as adsorb and immobile the TFSI− anions, significantly enhancing Li-ion transport kinetics. Furthermore, the in situ generated fast Li-ion conductor, i.e., Li$_x$TiN, derived from lithiated TiN, along with a smooth but dense LiF interphase, effectively bridges the electrolyte|electrode interface and suppresses Li dendrite growth. Consequently, the as-fabricated Li|PHLT|LiFePO$_4$ cells achieve exceptional cycling stability over 3000 cycles at 2 C with a superior average Coulombic efficiency of 99.8%. Notably, this strategy also enables great compatibility with matching high-loading cathodes (9.5 mg cm$^{−2}$), moreover, it delivers impressive performance in large areal pouch cells as well as bilayer stacking cells. This work provides an innovative approach to constructing solid-state electrolytes with enhanced diffusion kinetics and interface compatibility, paving the way for practical SSLMB applications

Induced saturation for complete bipartite posets

Given s, t ∈ N, a complete bipartite poset K$_{s,t}$ is a poset whose Hasse diagram consists of s pairwise incomparable vertices in the upper layer and t pairwise incomparable vertices in the lower layer, such that every vertex in the upper layer is larger than all vertices in the lower layer. A family F ⊆ 2[n] is called induced Ks,t -saturated if (F, ⊆) contains no induced copy of K$_{s,t}$ , whereas adding any set from 2[n] \F to F creates an induced K$_{s,t}$ . Let sat∗(n, K$_{s,t}$) denote the smallest size of an induced K$_{s,t}$ -saturated family F ⊆ 2[n]. It was conjectured that sat∗(n, K$_{s,t}$) is superlinear in n for certain values of s and t. In this paper, we show that sat∗(n, K$_{s,t}$) = O (n) for all fixed s, t ∈ N. Moreover, we prove a linear lower bound on sat∗(n, P) for a large class of posets P, particularly for K$_{s,2}$ with s ∈ N

A Coupled Inductor Based SSCB With Reduced Components for DC Microgrid Protection

DC microgrids have gained importance for their high efficiency, no need for synchronization, high power quality, and potential to reduce greenhouse gas emissions. Ensuring reliable and fast protection against over current and shor-circuit faults is considered to be a challenge even to date. Solid-state circuit breakers offer a promising solution, providing rapid and arc-less fault clearing. However, SSCBs employing fully controlled devices lead to higher costs and conduction losses. This paper discusses a cost effective circuit breaker, using a semi-controlled switch based on a coupled inductor. The proposed SSCB has reduced overall components, a discharged capacitor and also allows the option to trip manually for maintenance. A detailed analysis and design methodology for component selection is presented in the later sections. The SSCB is experimentally validated by developing a laboratory prototype for a voltage rating of 400 V and at a nominal current of 15 A & 20 A with a short circuit fault current of 60 A

Validation of Human-Variability Respecting Optimal Control: A Preparational Study

In order to design a performant and especially well perceived automation to assist the human in physical Human-Machine Interaction, an understanding of the human natural behavior is crucial. Model-based control design is therefore a favorable solution, already being used in various applications. However, most approaches model the human to be deterministic in it’s behavior, not aligning to the state-of-the-art models presented by neuroscience, which more accurately describe the human to be under the influence of noise processes. This paper presents a study that examines 13 participants performing point-to-point movements, followed by the identification of the underlaying cost as well as additive and multiplicative noise process parameters of a human stochastic model. The gained results provide a basis for future automations that explicitly incorporate human variability in their control design