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The pentagonal boron carbon nitride (penta-BCN) monolayer has been recently proposed as a new member of the pentagon-based two-dimensional nanosheets [Zhao et al., J. Phys. Chem. Lett. 11(9), 3501 (2020)]. By using density functional theory with the generalized gradient approximation, we have carried out detailed investigations of a hydrogenated penta-BCN sheet, where the pristine penta sheet is decorated with H atoms to the composition BCNH2. The hydrogenated penta-BCN (H-BCN) structure is mechanically, thermally, and dynamically stable. It has a wide and indirect bandgap of 4.46 eV, contrasting with the direct gap of 1.70 eV in pristine BCN. H-BCN is environmentally stable at 1 bar of H2 down to 10−10 bar; beyond this point, pristine BCN becomes more stable. Compared with penta-BCN, the components of the elastic modulus tensor C 11 and C 12 of hydrogenated penta-BCN are reduced, while C 12 and C 66 are increased. The strain tensors of piezoelectricity in H-BCN are d 21 = 0.462 , d 22 = 0.213 , and d 16 = 1.03 pm / V , which are lower than those of pristine penta-BCN. The hydrogenated BCN structure displays a higher spontaneous polarization Ps than penta-BCN (4.64 × 10−10 vs 3.38 × 10−10 C/m, respectively). The smaller in-plane Young's moduli E a and E b for H-BCN indicated that that they are softer than those for penta-BCN. Strain engineering can help tune electronic properties. In agreement with this claim, we found that the indirect gap of H-BCN was tunable from 4.46 to 3.26 eV under an applied tensile strain of 0%–16%, the range where the structure is dynamically stable throughout. Meanwhile, H-BCN is dynamically unstable under an applied compressive strain. [ABSTRACT FROM AUTHOR]

Solution‐processed copper(I) thiocyanate (CuSCN) typically exhibits low crystallinity with short‐range order; the defects result in a high density of trap states that limit the device's performance. Despite the extensive electronic applications of CuSCN, its defect properties are not understood in detail. Through X‐ray absorption spectroscopy, pristine CuSCN prepared from the standard diethyl sulfide‐based recipe is found to contain under‐coordinated Cu atoms, pointing to the presence of SCN− vacancies. A defect passivation strategy is introduced by adding solid I2 to the processing solution. At small concentrations, the iodine is found to exist as I− which can substitute for the missing SCN− ligand, effectively healing the defective sites and restoring the coordination around Cu. Computational study results also verify this point. Applying I2‐doped CuSCN as a p‐channel in thin‐film transistors shows that the hole mobility increases by more than five times at the optimal doping concentration of 0.5 mol.%. Importantly, the on/off current ratio and the subthreshold characteristics also improve as the I2 doping method leads to the defect‐healing effect while avoiding the creation of detrimental impurity states. An analysis of the capacitance‐voltage characteristics corroborates that the trap state density is reduced upon I2 addition. [ABSTRACT FROM AUTHOR]

Researchers studying Li-ion batteries (LIBs) have become very interested in two-dimensional (2D) materials possessing an unusual pentagonal atomic structure. Recently, penta-graphene, penta-B2C, and penta-BN2 have been theoretically described. These materials are attractive for use as state-of-the-art anodes in LIBs due to their high storage capacities of 1489, 1594, and 2071 mA h g−1, respectively. Here, we propose enhancing storage capacity by introducing defect doping. For example, one Al atom was incorporated into 2 × 2 penta-BN2, corresponding to AlB7N16. The energy calculated for the adsorption of a single Li atom onto the Al-doped material is more favorable than that for the Al-free analog, indicating that doping can strengthen an affinity for Li. The Al-doped penta-BN2 exhibits metallic conductivity during Li adsorption. In the layer-by-layer Li adsorption, doping a single Al atom into 2 × 2 penta-BN2 has an 11% higher storage capacity (2297 mA h g−1) than penta-BN2 despite having a slightly heavier formula weight. The Al-doped penta-BN2 displays a low open-circuit voltage of 0.48 V. Substituting aluminum for boron enhances the Li adsorption capacity of penta-BN2, and the computed storage capacity is presently one of the highest published values for pentagonal materials. [ABSTRACT FROM AUTHOR]

Copper(I) thiocyanate, defect healing, doping, hole transports, thin-film transistors Origin of Hole-Trapping States in Solution-Processed Copper(I) Thiocyanate and Defect-Healing by I2 Doping (Adv. Funct. Keywords: copper(I) thiocyanate; defect healing; doping; hole transports; thin-film transistors EN copper(I) thiocyanate defect healing doping hole transports thin-film transistors 1 1 1 06/22/23 20230619 NES 230619 B Hole Transports b In article number 2209504, Pichaya Pattanasattayavong and co-workers, report that X-ray absorption spectroscopy reveals the incomplete coordination environment around Cu(I) centers in CuSCN which can be associated with SCN SP - sp vacancies acting as hole-trapping states. [Extracted from the article]

The discovery of novel materials with high gas sensing selectivity is a key driver of gas sensor technology. Based on the recently reported two-dimensional (2D) pentagonal BeP 2 , we introduce penta-BeAs 2 as a new member of the pentagonal family of materials for toxic gas sensors based on density functional theory (DFT). For electronic applications, a band structure calculation showed that penta-BeAs 2 has indirect band gaps of 0.38 and 0.79 eV, using GGA-PBE or HSE functionals. Stability analysis confirmed that penta-BeAs 2 is dynamically, mechanically, and thermally stable. The adsorption of toxic gases (CO, NO, and NO 2 ) and nontoxic gases (H 2 , N 2 , H 2 O, and CO 2 ) on the penta-BeAs 2 monolayer was studied. The contrasting adsorption behavior observed between toxic and nontoxic gases on penta-BeAs 2 (physisorption vs chemisorption) underscores its high selectivity for toxic gas-sensing applications. Adsorption energies for toxic gases fall within a moderate range (0.4-0.8 eV), indicating good reversibility and short recovery times at room temperature. Additionally, the quantum transport properties of penta-BeAs 2 were studied using the nonequilibrium Green's function (NEGF) approach, confirming strong sensitivity and selectivity toward toxic gases.