In silico designing of efficient C-shape non-fullerene acceptor molecules having quinoid structure with remarkable photovoltaic properties for high-performance organic solar cells

Abstract

Non-fullerene acceptors (NFAs) are now under intense research to develop bulk-heterojunctions organic solar cells (OSCs). One fundamental approach to further improve the power conversion efficiency (PCE) of OSCs is to incorporate different end-capped units in a molecule. Herein, we efficiently designed a novel series of small molecule based non-fullerene acceptor molecules (CS1-CS5) by doing end-capped modification of NTTI (reference molecule) for OSCs and characterized with density functional theory (DFT) and time-dependent (TD-DFT) quantum chemical calculations. Narrowing of HOMO-LUMO energy gap is noted in designed molecules (Eg=1.73–1.90 eV) as compared to reference molecule (Eg=1.91 eV). Red-shifting is also observed in absorption spectrum of designed molecules (λmax=790–837 nm) as compared to R molecule (λmax=786 nm). The characteristic electron and hole mobility, and open-circuit voltage (Voc) were also computed which suggested that designed molecules have good electron and hole mobility along fine values of fine values of open circuit voltage values (0.97–1.44 V). Further, low binding energies and excitation energies (Ex =1.48–1.58 eV) allows high charge transfer and maximum power conversion efficiency in designed molecules. The results revealed that all newly constructed SMs-NFAs better exciton dissociation while, much lower LUMO energy levels which might facilitate to boost the reorganizational energies, open-circuit voltage, and photocurrent density values which will ultimately boosts the PCEs of the OSCs devices.