Small molecules non fullerene acceptors (NFAs) especially fused ring electrons accepters (FREAs) are the potential agents of revolution in organic photovoltaic devices. Fused ring core based organic solar cells (OSCs) have been revealed high power conversion efficiency; however, they still need further modification due to their low electron mobility. To make better FREAs with better electron mobility and enhanced optoelectronic properties, designing of accepter molecules through variation of end-capped units is considered a useful strategy now a day. Herein, an effort has been made to design and propose eight novel quad-rotor shaped fused ring core electron accepters (QRFR-1-QRFR-8) through modulating the four end-capped units of recently synthesized BFTT-TN molecule having quad–rotor structure., Employing DFT and TDDFT, optoelectronic properties of newly proposed accepter molecules have been determined through frontier molecular orbitals (FMO) analysis, density of states (DOS) analysis, transition density matrix (TDM), analysis of charge transfer and compared with reference molecule (BFTT-TN as QRFR).All the tailored molecules (QRFR-1-QRFR-8) disclose reduction in energy gap and intensive absorption near IR region than reference QRFR after end-capped engineering. The highest value of open circuit voltage (Voc) with respect to HOMOPM6–LUMOacceptor is found in QRFR-6 (1.66 V) than reference QRFR (1.63V) and comparable to reference QRFR in QRFR-8 molecule. Binding energies values of all designed molecules are found to be better and comparable with QRFR molecule. The reorganization energies of electron (λe) are found to be smaller than reference QRFR in all molecules except QRFR-5 molecule. The hole reorganization energies of QRFR-4, QRFR-8 QRFR-1, QRFR-2 are found to be less than QRFR. While λh of QRFR 6, QRFR-7, QRFR-3 and QRFR-5 are found to be higher than QRFR. The proposed quad-rotor shaped novel molecules have proficient hole and electron transfer mobilities and can serve as best candidate when blended with PM6 film. This study not only enlighten the researchers to use end-capped group modification as successful strategy for designing new quad-rotor shaped materials, but also provide novel materials to experimentalist for synthesis and their potential usage in future photovoltaic application of organic solar cell.

End-capped acceptor modification of fused-ring electron acceptors (FREAs) is an attractive strategy to boost the optoelectronic and photovoltaic properties of the materials. FREAsare proved beneficial due to their tremendous applications in organic solar cells (OSCs). Among fused-ring electronic species, small fullerene-free FREAs have already been drawn more attention due to their near-infrared sensitivity and constantly increasing efficiencies. Therefore, we have designed six new FREAs (K1-K6) having selenophene as π-bridge in between the central alkylated indaceno[1,2-b:5,6b]dithiophene (IDT) unit after the incorporations of various end-capped acceptors on to the recently synthesized IDT2SeC2C4-4F molecule. Structural-property relationship, photophysical and photovoltaic properties of newly designed molecules are studied with the help of density functional theory (DFT) and time-dependent-density functional theory (TD-DFT). Certain critical specifications like frontier molecular orbital (FMOs) alignment, the density of states (DOS), absorption maxima, excitation energy, binding energy (B.E) along with transition density matrix (TDM), and the specifically estimated re-organizational energy values of electron and hole and the open circuit voltages of newly designed molecules are computed and compared with reference molecule. Generally, a red-shifting absorption behavior of FREAs is considered the most important reason for their high efficiencies in OSCs. Our novel designed molecules exhibit redshift in the absorption spectrum. Similarly, low excitation and binding energies of designed molecules offer improved power conversion efficiencies (PCE) with the highest possible charge photo-current density (Jsc) in OSCs devices. Furthermore, the study of the PTB7-Th/K1 complex is also done in order to examine charge transfer between within complex. By introducing the efficient end-capped acceptor moieties in reference molecule, enhancement in charge mobilities is noted. The large open-circuit voltage, low reorganizational energies, narrower HOMO-LUMO energy gap, lower binding and excitation energies, and highly red-shifting in absorption phenomenon indicates an efficient designing of molecules that could be best fitted for high-efficiency OSCs. Finally, theorized molecules are much superior related to their photovoltaic and electronic properties and thus are recommended to experimentalists for their synthesis and out-looking future developments of highly efficient solar cell devices.

The introduction of a bridge element to covalently ring-lock the neighboring aryl or heteroaryl groups connected by a single bond has led to a variety of fascinating multifused ladder-type structures. Here, we have designed a new series of 2H-pyran containing tetracyclic dithienocyclopentapyran compounds (MMA1 to MMA3). Long conjugation at end-capped of designed systems enhances the power conversion efficiencies of non-fullerene-containing organic solar cells. Different geometric parameters of designed systems have been examined through density functional theory and time-dependent density function theory. Designed molecules expressed high absorption maxima values with a reduced energy bandgap. Open circuit voltage along with transition density matrix analysis recommended that charge transfer occurs from lower energy orbitals to higher energy orbitals. Reorganization energy analysis also suggested high charge mobility occurs from donor polymer to acceptor molecules. Results of all parameters advocated that designed molecules are potential candidates for high-performance organic solar cells.