High-K dielectric sulfur-selenium alloys

Abstract

Upcoming advancements in flexible technology require mechanically compliant dielectric materials. Current dielectrics have either high dielectric constant, K (e.g., metal oxides) or good flexibility (e.g., polymers). Here, we achieve a golden mean of these properties and obtain a lightweight, viscoelastic, high-K dielectric material by combining two nonpolar, brittle constituents, namely, sulfur (S) and selenium (Se). This S-Se alloy retains polymer-like mechanical flexibility along with a dielectric strength (40 kV/mm) and a high dielectric constant (K = 74 at 1 MHz) similar to those of established metal oxides. Our theoretical model suggests that the principal reason is the strong dipole moment generated due to the unique structural orientation between S and Se atoms. The S-Se alloys can bridge the chasm between mechanically soft and high-K dielectric materials toward several flexible device applications.

Beyond the Polysulfide Shuttle and Lithium Dendrite Formation: Addressing the Sluggish Sulfur Redox Kinetics for Practical High‐Energy Li‐S Batteries

“…X‐ray diffraction (XRD) characterizations (Figure e) showed that, after Se/S infiltration, the XRD pattern of the as‐prepared CSH‐S/Se‐10 % cathode is different from that of S8 (ICSD code: 63082), indicating the formation of a new phase after Se doping. X‐ray photoelectron spectroscopy (XPS) results for the CSH‐S/Se‐10 % and CSH‐S (insertion of pure sulfur into the CSH) further revealed that after doping with 10 wt % Se, Se 3p 1/2 (168.0 eV) and Se 3p 3/2 (161.8 eV) bonding can be identified in the CSH‐S/Se‐10 % cathode, while the CSH‐S S 2p spectrum did not show the Se 3p bonding (Figure f). Moreover, we fitted the Se 3d XPS spectrum and identified both Se−S (56.0 eV and 57.2 eV) and Se−Se (55.5 eV and 56.6 eV) bonds in the CSH‐S/Se‐10 % cathode, confirming the formation of a new phase rather than a physical mixture of S and Se.…”

“…X‐ray photoelectron spectroscopy (XPS) results for the CSH‐S/Se‐10 % and CSH‐S (insertion of pure sulfur into the CSH) further revealed that after doping with 10 wt % Se, Se 3p 1/2 (168.0 eV) and Se 3p 3/2 (161.8 eV) bonding can be identified in the CSH‐S/Se‐10 % cathode, while the CSH‐S S 2p spectrum did not show the Se 3p bonding (Figure f). Moreover, we fitted the Se 3d XPS spectrum and identified both Se−S (56.0 eV and 57.2 eV) and Se−Se (55.5 eV and 56.6 eV) bonds in the CSH‐S/Se‐10 % cathode, confirming the formation of a new phase rather than a physical mixture of S and Se. Such a new Se/S compound could possess distinct physical and chemical properties, such as better electronic conductivity, stability, and reversibility than that of individual S 8 molecule .…”

Beyond the Polysulfide Shuttle and Lithium Dendrite Formation: Addressing the Sluggish Sulfur Redox Kinetics for Practical High‐Energy Li‐S Batteries

“…X-ray diffraction (XRD) characterizations ( Figure 1e) showed that, after Se/S infiltration, the XRD pattern of the as-prepared CSH-S/Se-10 %cathode is different from that of S8 (ICSD code:6 3082), indicating the formation of an ew phase after Se doping. X-ray photoelectron spectroscopy (XPS) results for the CSH-S/Se-10 %and CSH-S (insertion of pure sulfur into the CSH) further revealed that after doping with 10 wt %S e, Se 3p 1/2 (168.0 eV) [38] and Se 3p 3/2 (161.8 eV) [38] bonding can be identified in the CSH-S/Se-10 %c athode,w hile the CSH-S S2ps pectrum did not show the Se 3p bonding (Figure 1f). Moreover,wefitted the Se 3d XPS spectrum and identified both SeÀS( 56.0 eV and 57.2 eV) [38,39] and SeÀSe (55.5 eV and 56.6 eV) [38,39] bonds in the CSH-S/Se-10 %c athode,c onfirming the formation of anew phase rather than aphysical mixture of Sand Se.Such an ew Se/S compound could possess distinct physical and chemical properties,s uch as better electronic conductivity, stability,a nd reversibility than that of individual S 8 molecule.…”

Patterning of the Surface Electrical Potential on Chalcogenide Glasses by a Thermoelectrical Imprinting Process

“…going from glass A to D) is the apparition of new bands at 152 cm -1 , 219 cm -1 and 474 cm -1 , they correspond to S-S bonds. 39,42,43 The first two bands, present only when the sulfur content exceeds 70 at.%, are linked to the formation of sulfur rings (S 8 ) inside the glass matrix. 39,42 Another evolution when increasing the sulfur content, is the regular decrease of the contribution of the Ge related entities (340 and 415 cm -1 ).…”

“…39,42,43 The first two bands, present only when the sulfur content exceeds 70 at.%, are linked to the formation of sulfur rings (S 8 ) inside the glass matrix. 39,42 Another evolution when increasing the sulfur content, is the regular decrease of the contribution of the Ge related entities (340 and 415 cm -1 ). This is consistent with the decrease of the Ge content in the composition when going from composition A to D. The Raman intensity of the modes related to Sb are not affected which is consistent with the fact the Sb content stays constant.…”