Structural modification of A-C-A configured X-PCIC acceptor molecule for efficient photovoltaic properties with low energy loss in organic solar cells.

Modification of terminal acceptors of non-fullerene organic solar cell molecule with different terminal acceptors can help in screening of molecules to develop organic photovoltaic cells with improved performance. Thus, in this work, seven new molecules with an unfused core have been designed and thoroughly investigated. DFT/TD-DFT simulations were performed on studied molecules to explore the ground and excited state characteristics. UV-Visible analysis revealed the red shift in the absorption spectrum (reaching 781 nm) owing to their smaller energy gap up to 1.94 eV. Furthermore, transition density matrix analysis demonstrated that peripheral acceptors extract the electron density from the core effectively. The effectiveness of our investigated molecules as materials for high-performing organic photovoltaic cells has been shown by an examination of their electron and hole mobilities for fast charge transfer. When combined with PTB7-Th, all molecules displayed high open circuit voltage. XP5 molecule exhibited highest open circuit voltage (1.70 eV) and lowest energy loss of 0.30 eV. All designed molecules exhibit the improved aforementioned parameters, which shows that these molecules can be used to develop competent solar devices in future.

Designing of fluorine-substituted benzodithiophene-based small molecules with efficient photovoltaic parameters.

In this study, four hole-transporting materials (JY-M1, JY-M2, JY-M3, and JY-M4) are designed by modifying benzothiadiazole-based core with diphenylamine-based carbazole via acceptors through thiophene linkers. The designed molecules exhibited deeper HOMO energy with smaller energy gaps than the reference JY molecule which enhance their hole mobility. The absorption spectra of the JY-M1, JY-M2, JY-M3, and JY-M4 molecules are located at 380 nm to 407 nm in the gaseous phase and 397 nm to 433 nm in the solvent phase, which is red-shifted and higher than the reference molecule, demonstrating that designed molecules possess improved light absorption properties and enhanced effective hole transfer. The dipole moments of the designed molecules (14.74 D to 26.12 D) indicate a greater ability for charge separation, solubility and will be beneficial to produce multilayer films. Moreover, the results of hole reorganization energy (0.38198 eV to 0.45304 eV) and charge transfer integral (0.14315 eV to 0.14665 eV) of designing molecules show improved hole mobility and lower recombination losses compared to the JY molecule. Overall, we suggested that the structural modifications in the designed molecules contributed to their enhanced efficiency in converting light energy into electrical energy and have the potential for utilization in solar devices, paving the way for future advancements in the field of photovoltaics.

Quantum Chemical Approach of Hexaammine (NH3)6 complexant with alkali and alkaline earth metals for their potential use as NLO materials.

In this study, nine new electron rich compounds are presented, and their electronic, geometrical, and nonlinear optical (NLO) characteristics have been investigated by using the Density functional theory. The basic design principle of these compounds is placing alkaline earth metal (AEM) inside and alkali metal (AM) outside the hexaammine complexant. The properties of nine newly designed compounds are contrasted with the reference molecule (Hexaammine). The effect of this doping on Hexaamine complexant is explored by different analyses such as electron density distribution map (EDDM), frontier molecular orbitals (FMOs), density of states (DOS) absorption maximum (λmax), hyperpolarizabilities, dipole moment, transition density matrix (TDM). Non-covalent interaction (NCI) study assisted with isosurfaces has been accomplished to explore the vibrational frequencies and types of synergy. The doping of hexaammine complexant with AM and AEM significantly improved its characteristics by reducing values of HOMO-LUMO energy gaps from 10.7eV to 3.15eV compared to 10.7 eV of hexaammine. The polarizability and hyperpolarizability (αo and ßo) values inquisitively increase from 72 to 919 au and 4.31 × 10-31 to 2.00 × 10-27esu respectively. The higher values of hyperpolarizability in comparison to hexaammine (taken as a reference molecule) are credited to the presence of additional electrons. The absorption profile of the newly designed molecules clearly illustrates that they are highly accompanied by higher λmax showing maximum absorbance in red and far-red regions ranging from 654.07 nm to 783.94 nm. These newly designed compounds have superior outcomes having effectiveness for using them as proficient NLO materials and have a gateway for advanced investigation of more stable and highly progressive NLO materials.

Quantum chemical investigation of Z-shaped heptazethrenes derivatives with detailed structural parameters and singlet fission for photovoltaic applications.

A variety of organic solar cells has been discovered, but there is a need for efficient optoelectronic material to obtain high power conversion efficiency. In this study, we derived new molecules from Z-shaped heptazethrene. We measured its photovoltaic parameters, including frontier molecular orbitals (where the energy gap decreases to 16% as compared to the reference), molecular electrostatic potential maps (more nucleophilic core), the density of states (partial and total), absorbance in Vis-IR region (in the range of 650-1000 nm), transition density matrix, and hole-electron mobility in terms of reorganization energy that showed 11% higher electron mobility (λe) and 52% higher hole mobility (λh) as compared to the reference. A comparable power conversion efficiency (∼9%) is obtained from a single photon. Using the concept of singlet fission, we can increase the efficiency twice using a single photon (based on the diradical character of the molecule). The diradical character of the entitled molecules was also calculated. The designed molecules fulfil the criteria of singlet fission that generate two excited triplets from a single photon (ES1>2ET1). The designed molecules are more stable than the reference indicated by the singlet-triplet energy gap, which is 37% higher. Hence this work assists the researcher in enhancing the efficiency of the solar cell.

Alkaline earth metals (Be, Mg, Ca) doped hexamine complexant with enhanced electronic and nonlinear optical properties.

Organic complexant hexamine (hexamethylenetetramine, HMTA) is doped with alkaline earth (AE) metals, and new complexes are designed systematically to explore their nonlinear optical (NLO) properties by carrying out DFT calculations. Optimization of afresh designed geometries has shown their sufficient thermodynamic stability. Moreover, the energy band gap of pure HMTA is 10.62 eV which is reduced up to 2.63 eV for our doped complexes. This shows that alkaline earth metals are effective in enhancing the electronic properties of a system. Time-dependent DFT calculations are achieved, and results show that higher absorption maxima (λmax) along with small transition energies (ΔE) have significantly increased the hyperpolarizability (ß0) values (21,338-220,585 au). This higher hyperpolarizability is an elementary prerequisite for improved NLO response of a material. Transition density matrix (TDM) analysis, density of states (DOS) analysis, and electron density difference map (EDDM) studies are executed to get information about electronic distribution, crucial transitions, and electron transfer properties. As a result of these findings, it can be concluded that alkaline earth metal-doped HMTA might be a competitor for NLO materials with remarkable optical and electronic properties and better future applications in the field of optoelectronics.

Enhancement of NLO properties of supersalt (Al(BH4)3)-doped graphene: a DFT study.

In this work, pure and supersalt-doped graphene is evaluated by the density functional theory (DFT) to explore its optical and electronic properties. The doping of supersalt Al(BH4)3 on graphene reduces the highest occupied molecular orbital and lower unoccupied molecular orbital (HOMO-LUMO) bandgap of graphene@Al(BH4)3 and graphene@2Al(BH4)3 to 3.57 and 3.55 eV from 3.61 eV. The improvement in the optoelectronic properties of the supersalt Al(BH4)3-doped graphene is determined by the upshift of UV absorption peak and dipole moment. Polarizability (α) values of graphene@Al(BH4)3, and graphene@2Al(BH4)3 increase to 14% and 26% in the comparison of pure graphene. The first hyperpolarizability (ßo) is increased from 0.44 (graphene) to 1295.4 au in graphene@2Al(BH4)3. Our findings suggest that Al(BH4)3-doped graphene could be an effective method for making graphene an efficient nonlinear optical material.

Shedding light on the optical and nonlinear optical properties of superalkali-doped borophene.

The present investigation highlights the two-dimensional design of several interesting superalkali-doped borophene derivatives for efficient nonlinear optics (NLO). The combination effects and resulting NLO responses of borophene (B36) and superalkali units (Li3O) were evaluated by orienting superalkali clusters at various sites, such as the hub, rim, and bridge, around an B36 molecule. The charge analysis was characterized by frontier and natural bond orbital analyses, a narrowed HOMO-LUMO bandgap and greater intramolecular charge transfers. Molecular electrostatic potential surfaces demonstrated enhanced optoelectronic features of these complexes that are viable due to Li3O adsorption. Singly doped and doubly doped complexes were considered, and their NLO properties were calculated. Bandgap energy was reduced approximately threefold when doped with two Li3O. As a considerably high figure of merit, first hyperpolarizability (ßo) values of up to five digits (including 10,611 au for complex A) prove that these systems can be utilized as promising candidates in various NLO applications.

Tuning the optoelectronic properties of triphenylamine (TPA) based small molecules by modifying central core for photovoltaic applications.

Small donor molecules based on fused ring acceptors exhibit encouraging photovoltaic properties and expeditious advancement in organic solar cells. Central core modification of non-fullerene acceptor materials is a favorable methodology to enhance electronic properties and efficiency for OSCs. Herein, four new donor molecules, namely, BDTM1, PYRM2, ANTM3, and NM4 are designed with a strong donor moiety triphenylamine, tetracyanobutadiene as acceptor unit, and thiophene as spacer linked to a modified central core. Geometric parameters, optical, electrical properties, effect of central core modification on tailored molecules BDTM1-NM4 are investigated and compared with reference DPPR. DFT together with TDDFT approaches using MPW1PW91 functional is used to study key parameters like absorption maximum (λmax), frontier molecular approach, ionization potential, electron affinity, the density of states, transition density matrix along with open-circuit voltage (VOC), dipole moment and reorganization energy. Among all these molecules, BDTM1 shows maximum calculated absorption λmax (817 nm) and the lowest band gap (2.54 eV). This bathochromic shift in BDTM1 is due to the presence of 4,8-dimethoxy-2,6-di-2-thienylbenzodithiophene as a strong electron-withdrawing group. Computed reorganization energies (RE) shows that BDTM1 has the highest hole and electron mobility among all designed molecules. Combination of BDTM1 donor and PC61BM acceptor further verifies charge transfer and their interaction. The results illustrate that designed donor molecules (BDTM1-NM4) are better in performance and are recommended for experimentation to develop efficient OSCs. Four new donor molecules, namely, BDTM1, PYRM2, ANTM3, and NM4 are designed with a strong donor moiety triphenylamine, tetracyanobutadiene as acceptor unit and thiophene as spacer linked to a modified central core. Geometric parameters, optical, electrical properties, effect of central core modification on tailored molecules BDTM1-NM4 are investigated and compared with reference DPPR.

DFT study of superhalogen-doped borophene with enhanced nonlinear optical properties.

The concern of the present study is to investigate the nonlinear optical properties of superhalogen-doped borophene owing to its broad applications. The first principle study of the material for its nonlinear optical properties elaborated its use for electrical and optical applications. The superhalogen-based borophene in lithium ion-based batteries and medical appliances have made it one of the most potential materials for optoelectronics. First, hyperpolarizability (ßo) of pure and doped B36 is computed, and the difference between their values was examined. The vertical ionization energy (VIE) was calculated for pure and doped systems. The interaction energy (Ei) for all combinations was computed. It would be expected to be one of the best materials to have high capacity and resistance. For all the calculations and to calculate the highest occupied molecular orbital and lowest unoccupied molecular orbital energy gap, the density functional theory (DFT) method was used. It is predicted that these combinations are more beneficial and can display better nonlinear optical (NLO) properties in electronic devices. Superhalogen-doped BF4 borophene-36 ground state optimized geometry, frontier molecular orbitals HOMO and LUMO, maximum absorption (λmax), density of states (DOS) analysis, and electrostatic potential diagram (MEP) are displayed here.

Exploring the optoelectronic and third-order nonlinear optical susceptibility of cross-shaped molecules: insights from molecule to material level.

In the present investigation, we use a dual computational approach (at single molecular and solid-state levels) to explore the optoelectronic and nonlinear optical (NLO) properties of cross-shaped derivatives. The solid-state electronic band structures of the compounds 1-3 (the derivatives of tetracarboxylic acid in cross-shaped having the core of benzene (1), pyrazinoquinoxaline (2), and tetrathiafulvalene (3)) are calculated. The calculated band gaps for compounds 1-2 are found to be direct bad gaps and compound 3 to be indirect bad gap with energy gaps of 2.749, 1.765, and 0.875 eV, respectively. The important optical properties including refractive index, absorption coefficients, loss functions, and extinction coefficient of these semiconductors are calculated at bulk level to seek their potential applications as efficient optoelectronic materials. Additionally, we use the Lorentz approximation to calculate the third-order NLO susceptibilities of compounds 1-3 using the molecular hyperpolarizability and solid-state parameters. The calculated third-order NLO susceptibilities of compounds 1-3 are found to be 6.92 × 10-12, 64.0 × 10-12, and 26.3 × 10-12 esu, respectively. Thus, the present study not only provides a way to connect the calculated third-order molecular NLO polarizability to NLO susceptibilities for compounds 1-3 through Lorentz approximation but also highlights the importance of central core modifications on their NLO susceptibilities.

DFT study of superhalogen and superalkali doped graphitic carbon nitride and its non-linear optical properties.

DFT calculations are carried out to investigate nonlinear optical (NLO) properties of superhalogen (BCl4) and superalkali (NLi4) doped graphitic carbon nitride (GCN). It is noted that the geometries of doped GCN are sufficiently stable. The energy gap for GCN is 3.89 and it reduces to 0.53 eV in our designed molecule G4. Change in the dipole and transition dipole moment is observed along with small transition energies which are responsible for higher hyperpolarizabilities. Doped GCN has larger first and second hyperpolarizabilities which are basic requirements for NLO response. The second hyperpolarizability of GCN enhances from 1.59 × 104 to 2.53 × 108 au when doping with BCl4 and NLi4. TD-DFT calculations show the absorption maxima of doped GCN range from 700 nm to 1350 nm. EDDM analysis provides information on electronic distribution from excited to ground state. All these consequences show doped GCN can be a promising NLO material.