Designing Thieno[3,4-c]pyrrole-4,6-dione Core-Based, A2-D-A1-D-A2-Type Acceptor Molecules for Promising Photovoltaic Parameters in Organic Photovoltaic Cells.

Nonfullerene-based organic solar cells can be utilized as favorable photovoltaic and optoelectronic devices due to their enhanced life span and efficiency. In this research, seven new molecules were designed to improve the working efficiency of organic solar cells by utilizing a terminal acceptor modification approach. The perceived A2-D-A1-D-A2 configuration-based molecules possess a lower band gap ranging from 1.95 to 2.21 eV compared to the pre-existing reference molecule (RW), which has a band gap of 2.23 eV. The modified molecules also exhibit higher λmax values ranging from 672 to 768 nm in the gaseous and 715-839 nm in solvent phases, respectively, as compared to the (RW) molecule, which has λmax values at 673 and 719 nm in gas and chloroform medium, respectively. The ground state geometries, molecular planarity parameter, and span of deviation from the plane were analyzed to study the planarity of all of the molecules. The natural transition orbitals, the density of state, molecular electrostatic potential, noncovalent interactions, frontier molecular orbitals, and transition density matrix analysis of all studied molecules were executed to validate the optoelectronic properties of these molecules. Improved charge mobilities and dipole moments were observed, as newly designed molecules possessed lower internal reorganization energies. The open circuit voltage (Voc) of W4, W5, W6, and W7 among newly designed molecules was improved as compared to the reference molecule. These results elaborate on the superiority of these novel-designed molecules over the pre-existing (RW) molecule as potential blocks for better organic solar cell applications.

High-Efficiency and Low-Energy-Loss Organic Solar Cells Enabled by Tuning the End Group Modification of the Terthiophene-Based Acceptor Molecules to Enhance Photovoltaic Properties.

In the current study, six nonfullerene small acceptor molecules were designed by end-group modification of terminal acceptors. Density functional theory calculations of all designed molecules were performed, and optoelectronic properties were computed by employing different functionals. Every constructed molecule has a significant bathochromic shift in the maximum absorption value (λmax) except AM6. AM1-AM4 molecules represented a narrow band gap (Eg) and low excitation energy values. The AM1-AM4 and AM6 molecules have higher electron mobility. Comparing AM2 to the reference molecule reveals that AM2 has higher hole mobilities. Compared to the reference molecule, all compounds have excellent light harvesting efficiency values compared to AM1 and AM2. The natural transition orbital investigation showed that AM5 and AM6 had significant electronic transitions. The open-circuit voltage (Voc) values of the computed molecules were calculated by combining the designed acceptor molecules with PTB7-Th. In light of the findings, it is concluded that the designed molecules can be further developed for organic solar cells (OSCs) with superior photovoltaic abilities.

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.

Designing Y-shaped two-dimensional (2D) polymer-based donor materials with addition of end group acceptors for organic and perovskite solar cells.

CONTEXT: For the advancement in fields of organic and perovskite solar cells, various techniques of structural alterations are being employed on previously reported chromophores. This way, molecules with all the properties desired for better performance of solar cells can be achieved. In this regard, theoretical modeling of chromophores has gained quite an interest due to its ability to save time, resources, and money. Herein, five new Y-shaped donor materials were theoretically engineered by adding electron-withdrawing acceptors on reported 2DP molecule. The results explored that, in comparison to 2DP, the produced molecules showed red shift in the absorption peaks, smaller bandgaps and binding energies, lower excitation potential, and greater dipole moment and were also highly reactive. When paired with PC61BM, proposed compounds exhibited higher estimated power conversion efficiencies and open-circuit voltage in contrast to 2DP. Individually, 2DP1 possessed the largest conductivity of electrons and the maximum mobility of holes, due to its computed lowest reorganization energies. The results illustrate the viability of the proposed procedure, opening doors for the manufacturing of required solar cells with enhanced photovoltaic properties. METHODS: Precisely, a DFT and TD-DFT analysis on 2DP and all of the proposed molecules was conducted, using the functional MPW1PW91 at 6-31G (d,p) basis set to examine their optoelectronic aspects; additionally, the solvent state computations were studied with a TD-SCF simulation. For all these simulations, Gaussian 09 and GaussView 5.0 were employed. Moreover, the Origin 6.0 software, Multiwfn 3.8 software, and PyMOlyze 1.1 software were utilized for the visual depiction of the graphs of absorption, TDM, and DOS, respectively, of the studied molecules. A number of crucial aspects such as FMOs, bandgaps, light-harvesting efficiency, electrostatic potential, dipole moment, ionization potential, open-circuit voltage, fill factor, binding energy, interaction coefficient, chemical hardness-softness, and electrophilicity index were also investigated for the studied molecules.

Novel A-π-D-π-A type non-fullerene acceptors of dithienyl diketopyrropopyrrole derivatives to enhance organic photovoltaic applications: a DFT study.

To boost the photovoltaic attributes of organic photovoltaic cells, seven dithienyl diketopyrropopyrrole (TDPP) donor-based A-π-D-π-A (acceptor-bridge-donor-bridge-acceptor) type molecules (TM1-TM7) were formulated by modifying the electron accepting ends of the reference molecule (TMR). Optical and quantum chemical parameters of seven synthesized molecules were investigated using density functional theory with the MPW1PW91/6-31G(d,p) functional. Several parameters that can be used to measure and improve the efficiency of solar cells have been analyzed and summed up. These parameters include binding energy of exciton, excitation energy of electron, reorganization energies, dipole moment, molecular electrostatic potential, charge mobility, wavelength of maximum absorption, open circuit voltage, short circuit current, fill factor, density of states, transition density matrices, as well as iso-surface and non-covalent interactions. Thus, all of our proposed structures are perceived to be superior to the reference in terms of the maximum possible solar energy yield in solar cells with bulk heterojunctions, as determined by analyses of our designed molecules for the aforementioned parameters.

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.

Designing neodymium-doped hexamine complexant as novel IR NLO material with extremely large non-linear optical behavior.

A new complex named HMNd has been basically designed by doping rare-earth neodymium metal inside the hexamine surface HM. Density functional theory (DFT) calculations were carried out using B3LYP functional with split basis set GENECP to examine their geometrical, electronic, and non-linear optical properties of newly designed complex HMNd. After getting stable geometry of HMNd, its optoelectronic properties were compared with pure HM surface to check the influence of doping. HMNd revealed the obvious reduction in band gap energies from 8.4 eV (HM) to 1.79 eV (HMNd) as confirmed through DOS analysis. The highest hyperpolarizability and linear isotropic polarizability values of 6.8 × 105 a.u and 262.81 a.u respectively are perceived in HMNd. Electronic and thermodynamic stability of the designed complex has been confirmed through their vertical ionization and interaction energies. As revealed through the UV-visible analysis, doping with neodymium metal (HMNd) shifts the absorption to IR region with λmax of 2699.63 nm which leads towards the production of new materials. These upshots highlight the adequacy of designed complex providing gateway for designing new IR NLO materials in laser frequency conversion technology having usages in versatile fields.

Carbazole-based donor materials with enhanced photovoltaic parameters for organic solar cells and hole-transport materials for efficient perovskite solar cells.

Five carbazole-based donor molecules are designed by structural engineering of reference molecule PF. The molecules are devised by substitution of thiophene bridged end-capped acceptor groups namely (2-methylenemalononitrile) PF1, (methyl 2-cyanoacrylate) PF2, (3-methyl-5-methylene-2-thioxothiazolidin-4-one) PF3, (2-(3-methyl-5-methylene-4-oxothiazolidin-2- ylidene) malononitrile) PF4, and (4-(5-methylthiophen-2-yl) benzo[c] [1, 2, 5] thiadiazol) PF5. A DFT investigation was performed at the selected DFT functional MPW1PW91/6-31G (d,p) to investigate the optoelectronic properties of PF and all designed (PF1-PF2) molecules. Several important characteristics, i.e., band gap (Eg), transition density matrix analysis, dipole moment (µ), density of states analysis, reorganization energies, open circuit voltage (Voc), and fill factor, were investigated. The comparison of energy levels of reference molecule and designed molecules unveils the fact that these molecules are efficient hole transport materials to be used in perovskite solar cells (PSCs). All the newly drafted molecules (PF1-PF5) show higher λmax values in solvent (Chlorobenzene) ranging from 529 to 614 nm than the reference PF (344 nm). Smaller band gap (Eg) values in a range of 2.27-1.9 eV for newly designed molecules are observed which are very much reduced when compared to reference PF. Lowered exciton binding energies (Eb) and reorganization energies for the electron (0.004279-0.0103337 eV) as compared to PF reveal that our molecules display higher electron mobility rates, and hence, these small molecules can be used as proficient donor materials in high-performance organic solar cells (OSCs) and better hole transport materials (HTMs) for possible application in perovskite solar cells.