Synergistic engineering of end-capped acceptor and bridge on arylborane-arylamine macrocycles to boost the photovoltaic properties of organic solar cells

Abstract

A new stream of donor- π -acceptor (D- π -A) type arylborane-arylamine based donor contributors namely (BN1, BN2, BN3, BN4, BN5) have been drafted by substituting the terminal 2,4,6-tris-(trifluoromethyl)phenyl groups of reference B4N2-FMes (designated as BNR in the current study) with thiophene followed by W1 (4-(5-methylthiophen-2-yl)benzothiadiazole), W2 (2-(3-methyl-5-methylene-4-oxothiazolidin-2-ylidene)malononitrile), W3 (3-methyl-5-methylene-2-thioxothiazolidin-4-one), W4 (2-methylenemalononitrile), W5 (2-cyanoacrylicaidmethylester) acceptor moieties respectively. The computational characterization was performed via reliable density functional theory at B3LYP/6–31G (d,p). The optoelectronic parameters of newly planned molecules have been cross-checked with the reference (BNR). The newly planned (BN1-BN5) conjugated macrocycles have manifested outperformed results. Amongst all, BN4 has displayed the lowest band gap (2.07 eV), highest λmax (672 nm) in dichloromethane (DCM), highest ionization potential (IP) and electron affinity (EA) owing to its functionalization with cyano (CN) containing strong electron pulling moieties. Out of all reported molecules, BN1 has explored the lowest reorganization energy (RE) value for the electron (λ- = 0.00224 eV) and hole (λ+ = 0.00266 eV) demonstrating its augmented charge transition. BN1 is characterized by the highest dipole moment (6.31 D) in DCM addressing its enhanced solubility. Amongst all, BN4 has explored the highest VOC (1.51 eV) due to its low-lying HOMO. To sum up, the thiophene bridged end-capped acceptor alteration approach has been proved persuasive in providing the gateway to devise optimistic photovoltaic materials. All currently planned donor contributors (BN1-BN5) ought to be targeted to assemble upcoming proficient organic solar cells (OSCs).