Reduction Of Energy Gap Research Articles

Buckling-induced variations in electronic, thermal, and optical properties of B[formula omitted]C[formula omitted]N[formula omitted] monolayer: DFT and AIMD computational approaches

Density functional theory is employed to study the novel properties of B3C2N3 monolayer to gain a deeper understanding of variation of electronic, thermal, and optical characteristics arising due to buckling effects. The band structure analysis reveals an energy gap reduction of the buckled B3C2N3 monolayer, causing a displacement of the band gap from the visible to the infrared range. Moreover, the buckling controls the location of the initially, and finally, direct band gap moving it from the K to the Γ point in the B3C2N3 monolayer. The phonon band structure calculations indicate that buckled B3C2N3 monolayers are dynamically stable, while ab-initio molecular dynamics simulations, AIMD, evaluate and confirm the thermal stability of both flat and buckled B3C2N3 monolayers. The buckling phenomenon at low temperatures has no a significant impact on the heat capacity contrary to what happens in the high temperature limit. The optical characteristics of the B3C2N3 monolayer, including refractive index, optical conductivity, static dielectric function, and plasmon frequency, are evaluated at different levels of the buckling parameter. The static dielectric function and plasmon frequency are enhanced with the buckling due to the screening of the electron–electron interactions, affecting the collective oscillations. Enhanced screening gives rise higher plasmon frequencies. Tuning the buckling parameter illustrates the significance of buckling as an alternative mechanism for adjusting the performance of B3C2N3 two-dimensional materials for different technological applications such as solar and optoelectronic systems.

Synergistic charge-transfer dynamics of novel benzothiadiazole-based donor materials for higher power conversion efficiency: From structural engineering to efficiency assessment in non-fullerene organic solar cells

In the realm of organic solar cell technology, current research is dedicated to enhancing the photovoltaic properties of donor-π-acceptor (D-π-A) materials to achieve higher power conversion efficiencies (PCE). This optimization focuses particularly on fine-tuning the conduction band and electrolytic characteristics to maximize performance. Addressing the growing demand for novel materials with enhanced optoelectronic properties in organic photovoltaic research, our proposed compound BT05, one of nine new benzothiadiazole-based D-π-A donor molecules (BT01-BT09), exhibits a power conversion efficiency (PCE) of 25%, surpassing the 18% PCE of the reference compound BTD-OMe. TD-DFT and DFT simulations illuminate how donor modifications enhance the photovoltaic characteristics of the proposed molecules. Higher open-circuit voltage (VOC) of 1.74-2.26 V, increase in binding energy (∼1.997), λmax (470-476 nm), reduction in energy gap (4.25-4.65 eV), also validates the PCE results and confirm the usefulness of designed molecules (BT01-BT09). Moreover, DHOMO and ALUMO, TDM, reorganization energy λe (0.0124-0.0134) and λh (0.0094-0.0098), and NPA results also confirm that BT01-BT09 molecules unlock the organic solar cell's potential and advance sustainable energy solutions through innovative technology. Among all developed compounds, BT05 displays higher VOC (2.26 V), 87% fill-factor, and 25% PCE; hence, it is recommended in future solar cell applications.

Structural activity of synthesized pyrimidine-thiophene and pyrimidine-thiadiazole conjugates as anticancer agents

New pyrimidine linked thiophene conjugates 5a-d and thiadiazole conjugates 7a-d through a carboxamide bridge were synthesized and characterized by the spectral data (IR, NMR and mass). Exploration of the isolated conjugates’ characteristics using DFT methodology revealed that they had angular configurations with distinctive outline of the FMO’s belonging to the thienyl- and thiadiazolyl-pyrimidine classes. In accordance, the FMO’s energy values of these analogues disclosed reduced energy gap (ΔEH-L=3.66–3.86 eV) than the parent 4 (4.49 eV) and may be arranged as: 7c < 7d < 5c < 5d < 5a < 5b < 7b < 7a < 4. Meanwhile, the cytotoxic effectiveness of the synthesized conjugates was assessed against different cancer cell lines using IC50 values in comparison to 5-Fu, drug reference. The data showed that the acrylamide derivative 4 exhibited the most potent cytotoxicity against MCF-7 and PC3 (IC50 6.11 ± 0.10 and 7.19 ± 0.04 μM, respectively). Moreover, the carbonic anhydrases inhibitory effect on hCA IX and hCA IIX have been evaluated, using acetazolamide (as standard), showing greater impact on hCA IX compared to hCA IIX. Molecular docking has been applied to investigate the nature of the binding interactions with the target amino acid residues, and it disclosed that the pyrimidine-thiophene conjugates 5d and 5c had the highest binding scores. Finally, the SwissADME pharmacokinetic properties of synthesized conjugates indicated that the acrylamide compound 4 exhibited acceptable pharmacokinetic manners, such GI absorption, solubility, no BBB permeation, and slight CYP450 inhibition, implying a promising therapeutic candidate.

Effect of Electron-Donating Substituents and an Electric Field on the ΔEST of Selected Imidazopyridine Derivatives: A DFT Study.

A series of thermally activated delayed fluorescent (TADF) molecules having an imidazopyridine acceptor, a benzene linker, and a 9,9-dimethyl-9,10-dihydroacridine donor are designed and examined using a quantum chemical approach. The above framework spatially separates the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), minimizing their overlap, ultimately resulting in a reduced energy gap between the excited singlet and triplet states (ΔEST). The impact of electron-donating substituents (-Me, -Et, -t-Bu, -OMe, and -NMe2) on the donor moiety of the parent molecule 2-(4-(9,9-dimethylacridin-10(9H)-yl)phenyl)imidazo[1,2-a]pyridine-3,6-dicarbonitrile (Ac-CNImPy) is investigated. The calculated results revealed that for a given substituent, the para-substituted derivatives exhibit relatively less ΔEST, compared to that of the respective ortho- and meta derivatives. The value of ΔEST decreased with an increase in the electron-donating capacity of the substituent. Additionally, the ΔEST of the disubstituted derivatives is found to be less than that for the monosubstituted derivatives. The charge transport studies revealed that molecules with strong electron-donating substituents act as electron transporters. The effect of an external electric field (EEF) on ΔEST of the parent molecule Ac-CNIMPY and its derivative is also examined and revealed that the ΔEST can be further reduced by applying an electric field of appropriate strength in a direction perpendicular to the dipole moment of the molecule and in the plane of the acceptor moiety.

Molecular Engineering of Pure Superoxide Radical Photogenerator for Hypoxia-Tolerant Tumor Theranostics.

Photodynamic therapy (PDT) is a promising cancer treatment, but limited oxygen supply in tumors (hypoxia) can hinder its effectiveness. This is because traditional PDT relies on Type-II reactions that require oxygen. Type-I photosensitizers (PSs) offer a promising approach to overcome the limitations of tumor photodynamic therapy (PDT) in hypoxic environments. To leverage the advantages of Type-I PDT, the design and evaluation of a series of Type-I PSs for developing pure Type-1 PSs, by incorporating benzene, thiophene, or bithiophene into the donor-acceptor molecular skeleton are reported. Among them, CTTI (with bithiophene) shows the best performance, generating the most superoxide radical (O2 •-) upon light irradiation. Importantly, CTTI exclusively produced superoxide radicals, avoiding the less effective Type-II pathway. This efficiency is due to CTTI's energy gap and low reduction potential, which favor electron transfer to oxygen for O2 •- generation. Finally, CTTI NPs are successfully fabricated by encapsulating CTTI into liposomes, and validated to be effective in killing tumor cells, even under hypoxic conditions, making them promising hypoxia-tolerant tumor phototheranostic agents in both in vitro and in vivo applications.

Exploring Aromaticity Effects on Electronic Transport in Cyclo[n]carbon Single-Molecule Junctions.

Cyclo[n]carbon (Cn) is one member of the all-carbon allotrope family with potential applications in next-generation electronic devices. By employing first-principles quantum transport calculations, we have investigated the electronic transport properties of single-molecule junctions of Cn, with n = 14, 16, 18, and 20, connected to two bulk gold electrodes, uncovering notable distinctions arising from the varying aromaticities. For the doubly aromatic C14 and C18 molecules, slightly deformed complexes at the singlet state arise after bonding with one Au atom at each side; in contrast, the reduced energy gaps between the highest occupied and the lowest unoccupied molecular orbitals due to the orbital reordering observed in the doubly anti-aromatic C16 and C20 molecules lead to heavily deformed asymmetric complexes at the triplet state. Consequently, spin-unpolarized transmission functions are obtained for the Au-C14/18-Au junctions, while spin-polarized transmission appears in the Au-C16/20-Au junctions. Furthermore, the asymmetric in-plane π-type hybrid molecular orbitals of the Au-C16/20-Au junctions contribute to two broad but low transmission peaks far away from the Fermi level (Ef), while the out-of-plane π-type hybrid molecular orbitals dominate two sharp transmission peaks that are adjacent to Ef, thus resulting in much lower transmission coefficients at Ef compared to those of the Au-C14/18-Au junctions. Our findings are helpful for the design and application of future cyclo[n]carbon-based molecular electronic devices.

Strategy to Efficient Photodynamic Therapy for Antibacterium: Donor-Acceptor Structure in Hydrogen-Bonded Organic Framework.

While the construction of a donor-acceptor (D-A) structure has gained great attention across various scientific disciplines, such structures are seldomly reported within the field of hydrogen-bonded organic frameworks (HOFs). Herein, a D-A based HOF is synthesized, where the adjacent D-A pairs are connected by hydrogen bonds instead of the conventionally employed covalent bonds. This structural feature imparts material with a reduced energy gap between excited state and triplet state, thereby facilitating the intersystem crossing (ISC) and boosting the generation rate of single oxygen (quantum yield = 0.98). Consequently, the resulting material shows high performance for antimicrobial photodynamic therapy (PDT). The impact of D-A moiety is evident when comparing this finding to a parallel study conducted on an isoreticular HOF without a D-A structure. The study presented here provides in-depth insights into the photophysical properties of D-A pair in a hydrogen-bonded network, opening a new avenue to the design of innovative materials for efficient PDT.

Thio and Seleno-Psoralens as Efficient Triplet Harvesting Photosensitizers for Photodynamic Therapy.

The Psoralen (Pso) molecule finds extensive applications in photo-chemotherapy, courtesy of its triplet state forming ability. Sulfur and selenium replacement of exocyclic carbonyl oxygen of organic chromophores foster efficient triplet harvesting with near unity triplet quantum yield. These triplet-forming photosensitizers are useful in Photodynamic Therapy (PDT) applications for selective apoptosis of cancer cells. In this work, we have critically assessed the effect of the sulfur and selenium substitution at the exocyclic carbonyl (TPso and SePso, respectively) and endocyclic oxygen positions of Psoralen. It resulted in a significant redshifted absorption spectrum to access the PDT therapeutic window with increased oscillator strength. The reduction in singlet-triplet energy gap and enhancement in the spin-orbit coupling values increase the number of intersystem crossing (ISC) pathways to the triplet manifold, which shortens the ISC lifetime from 10-5 s for Pso to 10-8 s for TPso and 10-9 s for SePso. The intramolecular photo-induced electron transfer process, a competitive pathway to ISC, is also considerably curbed by exocyclic functionalizations. In addition, a maximum of 115 GM of two-photon absorption (2PA) with IR absorption (660-1050 nm) confirms that the Psoralen skeleton can be effectively tweaked via single chalcogen atom replacement to design a suitable PDT photosensitizer.

Theoretical insights into long-range coupling of electron-hole pairs in TCTA–PO-T2T exciplex

This work reports theoretical investigations concerning long-range coupling of electron-hole pairs in spatially separated exciplex (SSE) systems via Density Functional Theory and Time-Dependent Density Functional Theory. Based on TCTA−PO-T2T parent exciplex, where 4,4′,4″-Tris(carbazol-9-yl)triphenylamine (TCTA) serves as donor (D) and 2,4,6-Tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) as acceptor (A), SSEs are constructed by intentionally tuning the D−A distance. The calculation results demonstrate that all SSEs, even if the D−A distance is over 14 Å, exhibit the clear and strong charge transfer character in terms of DCT, qCT, and t indexes. As the D−A distance increases, the energy gap of SSEs is increased, resulting in the blueshift of emission spectra. Calculation and experiment results show a good consistency, indicating that our model could well describe SSEs. Meanwhile, the reduced energy gap between CT and 3LE and more degenerate states could boost reverse intersystem crossing via vibronic coupling and hyperfine coupling, eventually improving the electroluminescent performance of SSEs. Our study suggests that manipulation of relative energy alignment via controlling D−A distance not only promotes the properties of exciplexes, but also offers guidance for designing thermally activated delayed fluorescence emitters through-space charge transfer.

DFT investigation of M2F superalkali doped dodecafluorophenylene (C13H10F12) derivatives with remarkable static and dynamic NLO response

Herein, based on density functional theory (DFT) simulations, the static and dynamic hyperpolarizabilities of the superalkalides based on Janus molecules have been explored. The designed superalkalides M2F(F)-DDFP-M2F(H) contain Janus based Dodecafluorophenylene (DDFP) molecule doped with superalkalis on both sides acting as both electron acceptors and donors. Thermodynamic stabilities are evident from the negative values of interaction energies, which are observed in the range of −2.96 eV to −3.63 eV. The maximum interaction energy (Eint) obtained is −3.63 eV for Li2F(F)-DDFP-Li2F(H) complex. The NBO (natural bond orbital) and FMO (frontier molecular orbital) analyses confirm the true superalkalide nature of the designed complexes. FMO analysis further reveals the reduction in energy gap E(H-L) from 10.43 eV (for bare DDFP) to 3.17 eV for the designed superalkalis. Furthermore, NLO response of the studied complexes reveals that the maximum values of polarizability (617 au) and hyperpolarizability are seen for Na2F(F)-DDFP-K2F(H) (4.25 × 104 au) complex, which confirms the remarkable NLO response of newly designed superalkalides. Moreover, frequency dependent analysis indicates that the maximum values of simple harmonic generation (SHG), electro-optical pockel effect (EOPE) and hyper Rayleigh scattering are 7.79 × 106, 2.75 × 106 and 4.45 × 106 au, respectively. The EOKE and EFISHG values are 6.79 × 107 and 7.68 × 1010 at 1339 nm suggesting significant increase in the NLO response of the reported complexes. These results manifest that our designed complexes might provide new paths towards the exceptionally high performance NLO materials. Moreover, we expect that the present work will provide guidance for designing and synthesis of superalkali based NLO materials in future.

Donor-Acceptor Modulating of Ionic AIE Photosensitizers for Enhanced ROS Generation and NIR-II Emission.

Photosensitizers (PSs) with aggregation-induced emission (AIE) characteristics are competitive candidates for bioimaging and therapeutic applications. However, their short emission wavelength and nonspecific organelle targeting hinder their therapeutic effectiveness. Herein, a donor-acceptor modulation approach is reported to construct a series of ionic AIE photosensitizers with enhanced photodynamic therapy (PDT) outcomes and fluorescent emission in the second near-infrared (NIR-II) window. By employing dithieno[3,2-b:2',3'-d]pyrrole (DTP) and indolium (In) as the strong donor and acceptor, respectively, the compound DTP-In exhibits a substantial redshift in absorption and fluorescent emission reach to NIR-II region. The reduced energy gap between singlet and triplet states in DTP-In also increases the reactive oxygen species (ROS) generation rate. Further, DTP-In can self-assemble in aqueous solutions, forming positively charged nanoaggregates, which are superior to conventional encapsulated nanoparticles in cellular uptake and mitochondrial targeting. Consequently, DTP-In aggregates show efficient photodynamic ablation of 4T1 cancer cells and outstanding tumor theranostic in vivo under 660nm laser irradiation. This work highlights the potential of molecular engineering of donor-acceptor AIE PSs with multiple functionalities, thereby facilitating the development of more effective strategies for cancer therapy.

Prediction of NbTaTiZr-based high-entropy alloys with high strength or ductility: First-principles calculations

Refractory high-entropy alloys (RHEAs) have a great potential in high-temperature electronics, extensive aerospace and biomedical applications due to their unique strength and ductility. Herein, the effects of alloying elements on the mechanical and electronic properties of NbTaTiZrX (X = V, Mo, Hf, W and Re) RHEAs are investigated by using the density functional theory (DFT) in combination with the special quasi-random structure (SQS) and virtual crystal approximation (VCA) methods. The calculated results show that alloying of Mo, W and Re with high elastic modulus can enhance the strength and the hardness of RHEAs. Among them, NbTaTiZrRe RHEA with the best strengthening effect has a yield strength of exceeds 2 GPa, which is notably higher than other considered high-entropy alloys. For alloying of V and Hf, the ductility of RHEAs is improved, and among which, NbTaTiZrHf RHEA has a relatively best ductility. Compared with other NbTaTiZrX RHEAs, spiral dislocations in NbTaTiZrHf RHEA are more prone to nucleate, and which confirms its excellent ductility. Moreover, the reduction of pseudo energy gaps and the formation of Hf–Hf strong metallic bonds further confirm its metallic ductility from the electronic density of states and charge density. The theoretical predictions in this study are congruent with the existing experimental data, and have certain theoretical guidance relevance for enhancing the mechanical characteristics of NbTaTiZrX (X = V, Mo, Hf, W and Re) RHEAs.

Role of Bridging Groups in Regulating the Luminescence and Charge Transfer Properties of Thermally Activated Delayed Fluorescence Molecules: A Theoretical Perspective.

Organic emitters with a simultaneous combination of aggregation-induced emission (AIE) and thermally activated delayed fluorescence (TADF) characteristics are in great demand due to their excellent comprehensive performances toward efficient organic light-emitting diodes (OLEDs), biomedical imaging, and the telecommunications field. However, the development of efficient AIE-TADF materials remains a substantial challenge. In this work, light-emitting properties of two AIE-TADF molecules with different bridging groups ICz-BP and ICz-DPS are theoretically investigated in the solid state with the combined quantum mechanics/molecular mechanics (QM/MM) method and the thermal vibration correlation function (TVCF) theory. The research indicates that the C═O bridging bond in ICz-BP is more favorable than the S═O bridging bond in ICz-DPS for enhancing the planarity of the acceptor, increasing conjugation, and thereby elevating the transition dipole moment density. Simultaneously, the stacking pattern of ICz-BP in the solid facilitates a reduction in energy gap between S1 and T1 (ΔEST), achieving rapid reverse intersystem crossing rate (kRISC). Furthermore, compared to toluene, the stacking patterns of ICz-BP and ICz-DPS in the solid effectively suppress the out-of-plane wagging vibration of the acceptor, thereby inhibiting the loss of nonradiative energy in the excited state and realizing aggregation-induced emission. Moreover, the charge transport properties of both electrons and holes in ICz-BP are found to be higher than the corresponding rates in ICz-DPS, attributed to the smaller internal reorganization energy of ICz-BP in the solid state. Additionally, the calculations reveal a more balanced charge transport characteristic in ICz-BP, contributing to efficient exciton recombination and emission and ultimately mitigating efficiency roll-off. Based on these computational results, we aim to unveil the relationship between molecular structure and light-emitting properties, aiding in the design and development of efficient AIE-TADF devices.

Computational modeling of oligothiophenes‐based donor molecules to boost optoelectronic attributes of organic solar cells

AbstractThe computational modeling of seven oligothiophene‐based donor molecules (TZ1–TZ7) designed by acceptor modification at the terminal position of the literature molecule (TZR) were discussed for organic solar cells (OSCs). DFT simulations using B3LYP/def2svp levels were performed to study the optoelectronic, and PV properties of TZ1–TZ7. A range of essential aspects for efficient small donor molecules like open circuit voltages (VOC), excitation energy (Ex), dipole moment (μ), density of state (DOS), absorption maxima (λmax), transition density matrix (TDM), binding energy (Eb), and frontier molecular orbitals (FMOs) of TZ1–TZ7 and TZR have also been investigated. DOS and FMOs analysis revealed a reduced energy gap (Eg) and effective charge transfer (CT) in the TZ1–TZ7 molecules. The absorption spectra were examined using TD‐DFT. Due to smaller Eg, Eb, Ex, and higher λmax, μ, the TZ1–TZ7 molecules exhibit remarkable optoelectronic properties. The computed VOC (0.969–1.189) and fill factor (0.886–0.897) for TZ1–TZ7 lead to improved power conversion efficiency (PCE) ranging from 14.05% to 17.60%. All compounds are strongly recommended for fabricating efficient OSCs with excellent PV properties. The current work is a step towards environmentally friendly organic PV and will pave the way for future structural engineering research for the efficient material design of OSCs.

Gap engineering effects on transport and tunneling magnetoresistance properties in phosphorene ferromagnetic/normal/ferromagnetic junction

Tuning the band gap is of utmost importance for the practicality of two-dimensional materials in the semiconductor industry. In this study, we investigate the ballistic transport and the tunneling magnetoresistance (TMR) properties within a modulated gap in a ferromagnetic/normal/ferromagnetic (F/N/F) phosphorene junction. The theoretical framework is established on a Dirac-like Hamiltonian, the transfer matrix method, and the Landauer–Büttiker formalism to characterize electron behavior and obtain transmittance, conductance and TMR. Our results reveal that a reduction in gap energy leads to an enhancement of conductance for both parallel and anti-parallel magnetization configurations. In contrast, a significant reduction and redshift in TMR have been observed. Notably, the application of an electrostatic field in a gapless phosphorene F/N/F junction induces a blueshift and a slight increase in TMR. Furthermore, we found that introducing an asymmetrically applied electrostatic field in this gapless junction results in a significant reduction and redshift in TMR. Additionally, intensifying the applied magnetic field leads to a substantial increase in TMR. These findings could be useful for designing and implementing practical applications that require precise control over the TMR properties of a phosphorene F/N/F junction with a modulated gap.

Predicting high performance optoelectronic attributes containing iso-indacenodithiophene-based photovoltaic materials for future solar cell technology

Enhancing photovoltaic materials with improved power conversion efficiency (PCE), conduction band, and electrochemical attributes for organic solar cell (OSC) applications is a forefront area of research. This study is centered on the simulating and computational characterization of iso-indacenodithiophen (iso-IDTIC)-based new molecules (AF01-AF10) to obtain optimal candidates for high-performance OSCs. The proposed molecules have excellent PCE (∼15.97 %), fill factor (54.67), and open-circuit voltage Voc = 1.41 V, better than previous reports. DFT simulations-based analysis, including TDM, FMO, MEP, DOS, Voc, reorganization energies of hole and electron, and charge transfer analysis, were employed to confirm and comprehend the photovoltaic properties of proposed molecules. Reduction in energy gap (2.30–2.50 eV), binding energy (0.28–0.29 eV), enhanced λmax (586–686 nm) with HOMO → LUMO (>96 %) charge transfer was examined as compared to R(2.54 eV, 608 nm). Moreover, higher excitation dissociation rate, TDM, HOMODonor-LUMOAcceptor blend study, and reorganizational energy for electron and hole results confirmed that proposed molecules are efficient photovoltaic candidates for future solar energy applications.

The behavior of low-symmetry penta(chloro)cyclotriphosphazene-substituted monophthalocyanines in the oriented external electric fields

Electric field-mediated chemistry provides fertile ground for interdisciplinary research, where theoretical ideas and experimental data converge to unravel the complexities of molecular behavior under the influence of electric fields, offering unprecedented opportunities for scientific research and technological innovation. Thus, this work is devoted to the study underscoring the importance of oriented external electric fields (OEEFs) in modulating the structural and electronic properties of low-symmetry monophthalocyanines, which is crucial for enhancing their reactivity and nonlinear optical response. The highlight of this article is that the OEEFs lead to molecular conductivity due to reduced energy gap and electron density shifting towards the phosphazene ring. Additionally, there is a tendency for the elimination of chlorine atoms in the trans- position relative to the phthalocyanine macrocycle. Also, the use of the previously created CORRELATO algorithm has allowed the demonstration of the relationship between structural changes and microscopic parameters responsible for the appearance of NLO properties of final dye materials.

Type-I Photodynamic Therapy Induced by Pt-Coordination of Type-II Photosensitizers into Supramolecular Complexes.

Platinum supramolecular complexes based on photosensitizers have garnered great interest in photodynamic therapy (PDT) due to Pt (II) centers as chemotherapeutic agents to eliminate tumor cells completely, which greatly improve the antitumor efficacy of PDT. However, in comparison to precursor photosensitizer ligand, the formed platinum supramolecular complexes typically exhibit inferior outcomes in terms of reactive oxygen species (ROS) generation. How to boost ROS generation in the formed platinum supramolecular complexes for enhanced PDT is an enticing yet highly challenging task. Here we report a Pt-coordination-based dimeric photosensitizer complex (Cz-BTZ-Py)2Pt(OTf)2. It is found that comparing with photosensitizer ligand Cz-BTZ-Py, the formed supramolecular complex exhibit redshifts of absorption wavelength as well as enhanced ROS generation efficiency. Moreover, type-I ROS generation (O2⋅-) is produced in the formed platinum supramolecular complexes mainly due to a reduced energy gap ΔEST resulting from exciton coupling between two photosensitizer ligands. And type-I ROS (O2⋅-) generation significantly amplifies the photodynamic therapy (PDT) outcomes. In vitro evaluation shows excellent photochemotherapy performance of (Cz-BTZ-Py)2Pt(OTf)2 nanoparticles. We anticipate this work would provide a novel approach to design type-I photosensitizers for efficient PDT.

Realizing an ultralow thermal conductivity via interfacial scattering and rational-electronic band reformation in p-type Mg3Sb2

Eco-friendly Magnesium antimonide (Mg3Sb2) has been extensively investigated as a promising and low-toxic thermoelectric material for intermediate (500–900 K) thermoelectric applications. Herein, p-type Zn-incorporated Mg3Sb2 was prepared by hot press technique, and its thermoelectric transport properties were investigated. The formation of Mg3−xZnxSb2 solid-solution plays a significant role in enhancing electrical conductivity of 34.59 S cm−1 due to the increased carrier concentration and reduced energy gap. Reduction in lattice thermal conductivity of 0.46 W m−1 K−1 at 753 K was obtained for Mg3−xZnxSb2 (x = 0.15) by combined scattering effect of dislocations, lattice strain, and interfaces, which is clearly seen in HR-TEM and strain analysis. These favorable conditions lead to an enhanced thermoelectric figure-of-merit (zT) of 0.25 at 753 K, which is 400% improved compared to the pure Mg3Sb2 sample.

Photocatalytic activity enhancement of g-C3N4 nanosheets through simultaneous inter- and intra-layer charge separation using a facile mechano-thermal method

Herein, a novel mechano-thermal approach has been proposed to tune the electronic structure and enhance the photocatalytic performance of g-C3N4 nanosheets. According to the results, the high-energy ball-milling method modified the role of the ammonium chloride from the blowing agent to the doping agent, leading to the introduction of the interstitial and substitutional Chlorine (Cl) atoms into the nanosheet structure. Such a modification not only promoted electron-hole separation through the inter- and intra-layer of the g-C3N4 nanosheets, but it also led to the band gap energy reduction and higher oxidation capability of the photogenerated holes. These key improvements have been reflected in the optimized sample with a high-energy ball-milling time of 15 min (g-C3N4–15). Compared to the sample without the ball-milling process, g-C3N4–15 exhibited simultaneous intra- and inter-layer charge separation, reduction in the band gap energy from 2.82 to 2.76 eV, and positive shift in the valence band. Furthermore, these modifications in the electronic structure of the nanosheets contributed to the outstanding photocatalytic performance of the g-C3N4–15 towards methylene blue (MB) photodegradation. Among the samples with different ball-milling times, g-C3N4–15 demonstrated the highest MB photodegradation rate constant (0.0125 min−1), approximately 9 times greater than the sample without the ball-milling process. Additionally, the proposed photodegradation pathway suggested that the positive shift in the valence band of g-C3N4–15 could activate hydroxyl radicals (.OH) and promote demethylation and ring-opening of MB dyes.