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One key strategy to further improve the power conversion efficiency (PCE) of organic solar cells (OSCs) is to incorporate various complementary functional groups in a molecule. Such strategies proved attractive for tuning the photovoltaic performances of the materials and can show a much higher absorption phenomenon with narrower band gaps. Despite the outstanding benefits, materials selection and their efficient modeling is also an extremely challenging job for the development of OSCs materials. In this manuscript, we proficiently developed an efficient series of small molecule-based non-fullerene acceptors (SM-NFAs) SN1-SN9 for OSCs and characterized by density functional theory (DFT) and time-dependent DFT (TD-DFT). The characteristics required to estimate electron and hole mobility, and open-circuit voltage (Voc) were investigated by optimizing the geometrical parameters, absorption spectra, exciton binding energy, frontier molecular orbitals (FMOs), electronic structures, and charge transfer rates. The outcomes of these materials showed that all newly constructed small-molecule-based non-fullerene acceptors exhibit broader and better absorption efficiency (λmax = 761 to 778 nm) and exciton dissociation, while much lower LUMO energy levels which may help to enhance the reorganizational energies. Further, a narrow bandgap also offers better photovoltaic properties. Hence, the designed molecules exhibited narrow bandgap values (Eg = 2.82 to 2.98 eV) which are lower than that of the reference molecule (3.05 eV). High Voc and photocurrent density values with lower excitation and binding energies eventually increase the PCEs of the OSC devices. The obtained results have shown that designed molecules could be effective aspirants for high-performance OSCs. Highlights: Half-moon-shaped fullerene-free acceptor molecules (SN1-SN9) are studied for organic solar cells applications. Significant lowering of energy gap with concomitant red-shifting of the absorption spectra is achieved with end-group engineering. The acceptors molecules show lower binding energy and excellent electron and hole reorganizational energies. All acceptor molecules have remarkable optoelectronic properties compared to reference R. [ABSTRACT FROM AUTHOR]

Development of novel materials for organic solar cells is a booming area of current research. Fused-ring electron accepters are the potential agents of revolution in organic photovoltaic devices and revealing high efficiency in organic solar cells. This study highlights the novel quad-rotor-shaped molecules as first example of efficient fused-ring non-fullerene acceptor materials with proficient photovoltaic parameters for their utilization in high-performance organic solar cells. First time, eight quad-rotor-shaped fused-ring electron accepters (QRFR-1–QRFR-8) are developed via modulating end-caps of experimentally synthesized (BFTT-TN) molecule (QRFR). Optoelectronic properties of proposed molecules are determined using frontier molecular orbitals (FMO), UV–Visible, density of state (DOS), overlap DOS (ODOS), transition density matrix (TDM) heat maps, open circuit voltage (Voc), binding energies (Eb), reorganization energy of electron (λe), hole (λh), charge transfer analysis, and compared with reference QRFR. All proposed fused-ring electron accepters disclose less energy gap and λmax in near IR region than QRFR after end-capped engineering. Highest Voc with respect to HOMOPM6–LUMOacceptor is found 1.66 V in QRFR-6 than QRFR (1.63 V). Eb values of QRFR-1–QRFR-8 are found better and comparable with QRFR. The λe is found smaller than QRFR in all molecules except QRFR-5. The proposed quad-rotor-shaped molecules exhibit proficient photovoltaic features and can serve as best candidate for organic solar cells when blended with PM6 film. This study not only enlightens the researchers to use end-capped reforms as effective tactic for designing materials, but also provides novel quad-rotor-shaped materials to experimentalist for synthesis and their usage in future application of organic solar cells. [ABSTRACT FROM AUTHOR]

Non-fullerene small molecular acceptors (NFSMAs) exhibit promising photovoltaic performance which promoted the rapid progress of organic solar cells (OSCs). In this study, an attempt is done to explore indenothiophene-based high-performance small molecular electron acceptors for organic solar cells. We have designed five acceptor molecules (M1–M5) with strong donor moiety indenothiophene linked to five different end-capped group acceptor moieties: diflouro-2-methylene-3-oxo-2,3-dihydroindene-1-ylidene)malononitrile (A1), 1-(dicyanomethylene)-2-methylene-3-oxo-2,3-dihydro-1H-indene-5,6-dicarbonitrile (A2), methyl-6-cyano-3-(dicyanomethylene)-2-methylene-1-oxo-2,3-dihydro-1H-indene-5-carboylate (A3), 2-(6-cyano-5-fluoro-2-methylene-3-oxo-2,3 dihydro-1H-indene-1-ylidene)malononitrile (A4), and (Z)-methyl 3-(benzo [c][1,2,5]thiadiazol-4-yl)-2-cyanoacrylate (A5) respectively. The structure–property relationship was studied and effects of structural modification on the optoelectronic properties of these acceptors (M1–M5) were determined systematically by comparing it with reference molecule R, which is recently reported as excellent non-fullerene-based small acceptor molecule. Among all designed molecules, M5 is proven as a suitable candidate for organic solar cell applications due to better photovoltaic properties including narrow HOMO-LUMO energy gap (2.11 eV), smallest electron mobility (λe = 0.0038 eV), highest λmax values (702.82 nm in gas) and (663.09 nm in chloroform solvent) and highest open-circuit voltage (Voc = 1.49 V) with respect to HOMOPTB7-Th–LUMOacceptor. Our results indicate that introducing more end-capped electron-accepting units is a simple and effective alternative strategy for the design of promising NFSMAs. This theoretical framework also proves that the conceptualized NFSMAs are superior and thus are recommended for the future construction of high-performance organic solar cell devices. [ABSTRACT FROM AUTHOR]

Here, we computed the Y1-Y4 acceptors by end-capped alterations on reference R to optimize photophysical, optoelectronic, and photovoltaic properties. Herefore, certain properties such as the orientation of FMO's, excitation and binding energy, open-circuit voltage, transition density matrix, and reorganizational energy of electron and hole are also observed and associated with the reference. The Y1 and Y4 calculated molecular structures showed a high red-shifting while Y2 and Y3 slightly blue-shifting, very fine excitation energies and high charge mobilities. All these molecules (Y1-Y4) and the reference R display band-gaps as small as 1.5–2.5 eV, and considerable charge-shifting potential. This theoretical system shows that end-capped acceptors alteration is quite remarkable to establish desired optoelectronic properties. [Display omitted] • Efficient electron acceptor materials (Y1-Y4) have been designed to produce highly efficient solar cell devices. • The structural–property relationship, photovoltaic and opto-electronic properties of designed molecules were investigated and compared with reference R. • All designed molecules displayed remarkable binding energy values, fine excitation energies, better open-circuit voltage, and high charge mobilities than R. • All designed molecules show that end-capped acceptors alteration is remarkable to establish desired optoelectronic properties. Non-fullerene organic solar cells (OSCs) deliver the highest efficiency gains overall in reported literature. Efforts are being made to refine efficacies and stabilities of organic solar cells through the designing of acceptor molecules that contain powerful electron-withdrawing groups. Here, we computed four acceptors (Y1-Y4) by end-capped alterations on reference R and optimize photophysical, optoelectronic and photovoltaic properties. Therefore, certain properties such as orientation of FMO's, excitation and binding energy, open-circuit voltage (V oc), transition density matrix and reorganizational energy of hole and electron are observed in comparison with reference. The calculated molecular structures of Y1 and Y4 show a high red-shift, while that of Y2 and Y3 display slightly blue-shift, along with very fine excitation energies and high charge mobilities. All these molecules (Y1-Y4) and the reference R presents band-gaps as small as 1.5–2.5 eV, and considerable charge transfer potential. This theoretical system shows that end-capped acceptors alteration is quite remarkable to establish desired optoelectronic properties. Thus, Y1-Y4 are suggested to researchers aiming at the potential commercialization of highly efficient solar cells systems. [ABSTRACT FROM AUTHOR]

• DFT and TDDFT calculations were performed on N -phenylaniline-triazol configured donor materials for efficient solar cells. • Six donor photovoltaic molecules (T1-T6) were designed by changing acceptor moieties of renowned synthesized TAZ-[MeOTPA] 2 molecule. • The electronic, optical and photovoltaic properties were studied in detail. • The FMOs, DOS graphs, reorganization energies, open circuit voltage, TDM surfaces and charge transfer characteristics were evaluated. • The studied compounds are proposed to be better entrants for organic solar cell applications. • This work may provide useful means in designing of new photovoltaic compounds. Considering the significant role of photovoltaic materials in diverse optoelectronic applications, N -phenylaniline-based six new donor molecules (T1-T6) are quantum chemically explored herein. Various parameters like frontier molecular orbital (FMO), density of states (DOS), transition density matrix (TDM) analysis, absorption maxima, reorganization energies of electron and hole, open circuit voltage (V oc), photophysical characteristics and charge transfer analysis have been estimated in order to understand the performance of newly designed molecules. End caped acceptors modification causes narrowing of HOMO-LUMO energy gap (2.99–3.33 eV) as compared to R (4.04 eV). All designed molecules exhibited absorption spectrum in the range of 334–370 nm in solvent phase and 324–403 nm in gas phase. T1-T6 show maximum charge transfer from HOMO to LUMO orbital which plays a key role in conductive materials. Dipole moment value of designed molecules in ground and excited states are found to be larger than reference molecule which suggested that our designed molecules have more solubility in organic solvent as compared to reference molecule. All designed molecules show better reorganizational energy of electron (0.0191–0.0273 E h) and hole (0.0063–0.0187E h). Among designed molecules T3 has lowest reorganizational energy of electron which means that it has highest charge mobility. The V oc with respect to HOMO donor -LUMO PC61BM shows that designed molecules [ T1-T6 (V oc = 1.08–1.50 V)] have better V oc as compared to R (V oc = 0.73 V). This theoretical framework proves that conceptualized molecules are superior and thus are recommended for the future construction of high performance organic solar cells. [ABSTRACT FROM AUTHOR]

• Five non-fullerene organic molecules are designed from the BTP-Cl molecule. • The newly designed molecules have better photovoltaic parameters (such as charge mobility) due to the introduction of highly efficient acceptor moieties. • The entitled molecules exhibited better absorption coefficient in chloroform solvent as compared to the previously reported BTP-Cl molecule. • Efficient acceptor groups decreases about 10 times the band gap energy as compared to chlorine-based BTP-Cl molecule. To enhance the efficiency of organic solar cells (OSCs), five non-fullerene π-conjugated acceptor molecules namely BTM1 , BTM2 , BTM3 , BTM4 and BTM5 are designed from recently reported 16.5% efficient acceptor molecule BTP-Cl. The molecules in the present quantum chemical investigation consist of benzothiazole (BT) core with different chemical species on the terminal side. The optoelectronic study of BTM1-BTM5 reveals that BTM3 and BTM4 molecules are superior with respect to absorption range found at the wavelengths of 780 and 791 nm as compared to 746 nm of reference molecule BTP-Cl. Frontier molecular orbital (FMO) and transition density matrix (TDM) analysis are performed that give basic information about the distribution of charges among investigated molecules. All investigated molecules exhibit charge density spread over the entire molecules. The BTM4 and BTM5 molecules efficiently transfer their electron densities from highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) with narrow bandgaps of 1.86 eV and 2.14 eV respectively. The electron mobility for BTM3 (0.00527), BTM4 (0.005820) and BTM5 (0.00539) are found less than BTP-Cl (0.00643). Similarly, BTM5 gives the least value of hole mobility (0.00558) as compared to BTP-Cl (0.00803). The binding energies of these molecules are also observed less (0.28 eV, 0.29 eV and 0.33 eV for BTM3 , BTM4 and BTM5) in gas phase than BTP-Cl (0.35 eV). Also, BTM5 is tested with donor polymer PTB7-Th that provides further evidence for their interactions. It turned out that the structural tailoring at terminals can tune effectively the frontier molecular orbital energy levels, band gap, absorption spectra, open-circuit voltage, reorganization energy and binding energy value in investigated molecules. Our results suggest that the investigated molecules can serve as fine acceptor materials. Additionally, some investigated molecules can also be used as a hole and/or electron transport materials for OSCs. [ABSTRACT FROM AUTHOR]

• Ten novel compounds with naphthalene-fused octacyclic core are designed for solar cell applications. • Electronic, photophysical and photovoltaic features are explored using computational tools. • Augmented optoelectronic properties are predicted in proposed molecules. • The designed compounds are recommended for stable and efficient organic solar cells. To meet the growing need for high-efficiency photovoltaic materials in today's high-tech applications, ten acceptor molecules (SH01-SH10) with naphthalene-fused octacyclic electron-donating central core NITT are proposed. End-capped structural-alterations on reference R (NITT-2F) with strong electron-drawing groups (A01-A10) are performed for attaining improved optoelectronic characteristics and possible applications in organic solar cells (OSCs). In comparison to the reference R (NITT-2F), key parameters such as FMO analysis, energy gap (E gap), open-circuit voltage (V OC), absorption spectra (λ max), excitation energy (E x), transition density matrix (TDM) with binding energy (E b), the density of states (DOS), reorganization energy of the electron (λ e) and hole (λ h), and charge transfer with PM6 donor substance are perceived. It is found that all proposed molecules (SH01-SH10) have a reduced energy gap (2.104–1.901 eV), a broader absorption spectrum (707–820 nm), and smaller excitation energy (1.75–1.51 eV) as compared to reference molecule NITT-2F values 2.132 eV, 675 nm and 1.79 eV respectively. The significant charge transfers and 0.23 eV decrease in the E gap is noted for the designed molecule SH05. Results confirmed that all proposed molecules, especially SH05 could be an excellent choice for OSCs candidate due to the combination of strong electron-withdrawing effect in end-capped acceptor unit and extended conjugation, as well as its promising photovoltaic properties, which include the lowest E gap (1.901 eV), highest λ max (820 nm (in chloroform) and 729 nm (in gas phase)) with E x values of 1.51 and 1.70 eV respectively, slightest electron mobility (λ e = 0.0090 eV) and hole mobility (λ h = 0.0073 eV), highest ionization potential (6.826 eV) and electron affinity (3.384 eV), and fine value of V OC =1.02 V with respect to (ǀEPM6 HOMO ǀ - ǀESH05 LUMO ǀ). End-capped acceptor alterations are an acceptable way to attain the desired optoelectronic characteristics demonstrated in this research work. This study can be essential in achieving efficient novel non-fullerene OSCs with higher performance, low cost, and higher optical absorption coefficient. Thus, proposed molecules (SH01-SH10) with proficient electron and hole transfer mobilities and optoelectronic features are recommended to develop higher-efficiency solar cells. [Display omitted] [ABSTRACT FROM AUTHOR]