Theoretical designing of novel quad-rotor-shaped non-fullerene acceptor
materials with proficient photovoltaic characteristics for organic solar
cells
Abstract
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.