Influence of benzothiophene based acceptors modulation on photovoltaic properties of Trimethyl-2-selena-5-aza-pentalene-4,6-dione based chromophores through quantum chemical investigations

Abstract

Non-fullerene organic compounds are widely utilized to enhance the efficiency of photovoltaic materials. Herein, we designed a series of novel selenophene based compounds (DSBD1-DSBD8) with A₁–π–A₂–π–A₁ architecture from DSBDR, which was derived from recently synthesized TPD-T-CN compound. The structural design process involved replacing the thiophene rings with selenophene units, which possess a higher degree of polarization, and altering the various terminal acceptor units of TPD-T-CN. Various analyses such as absorption properties (UV–Vis), open circuit voltage (V_oc), density of states (DOS) were executed at CAMB3LYP/6-311G(d,p) functional, to analyze the optical and photovoltaic parameters of designed compounds. All the designed molecules (DSBD1-DSBD8) were observed with suitable band gaps (ΔE = 2.690–2.542 eV) with larger bathochromic shifts (λ_max = 610.098–642.505 nm in dichloromethane) than DSBDR. The lower binding energy values (E_b = 0.658–0.612 eV) indicated easy charge transport between molecular orbitals with the higher exciton. Further, V_oc analysis was conducted with respect to HOMO_PBDBT-LUMO_ACCEPTOR and all of the derivatives exhibited a comparable voltage value with that of the reference chromophore. Therefore, it can be inferred that through molecular engineering with efficient acceptor moieties and integrating selenophene rings, the efficiency of NF-based photovoltaic materials could be improved.