Exploration of photovoltaic behavior of benzodithiophene based non-fullerene chromophores: first theoretical framework for highly efficient photovoltaic parameters

Abstract

Keeping in view, the recent energy conditions and contribution of non-fullerene acceptors (NFAs) towards organic solar cells (OSCs), a series of NFAs (D1-D9) was designed. The novel fused ring NFAs (D1-D9) having A-D-A architecture were designed by structural engineering of R molecule with effective benzothiophene based acceptor moieties. For current study, all the calculations were accomplished at M06/6-311G (d,p) level. Different computational approaches like density of states (DOS), binding energy (Eb), transition density matrix (TDM), absorption spectra (UV–Vis), electronic properties (FMOs) and open circuit were performed to investigate the photovoltaic response of newly designed D1-D9 chromophores. The terminal substitution of end-capped acceptors exhibited a reduction in energy gap (ΔE = 2.222–1.986 eV) with high electron mobility rate in all the derivatives (D1-D9) than that of R. All the designed chromophores exhibited wider absorption spectrum (λmax = 845.039–786.552 nm) along with lower excitation energy as compared to R (λmax = 770.040 nm) except D1 and D9. Interestingly, lower binding energy (Eb = 0.419–0.473 eV) accompanying with higher excition dissociation rate was seen in derivatives than that of reference compound. Moreover, a comparable value of Voc was noted in derivatives when calculated via LUMOacceptor–HOMOPBDBT. Among all fore-said chromophores (D1-D9), D4 exhibited lowest binding energy and thus ensured easier and faster excition dissociation rate along with highest Voc (1.586 V). In cessation, this structural modification by utilizing various acceptors played a significant role in obtaining auspicious photovoltaic response in compounds. Hence, our study encourages the experimentalists for synthesizing these proposed organic systems for the attaining high efficacy photovoltaic devices.

Keywords

• Benzodithiophene
• Photovoltaic response
• NF-OSCs
• A-D-A framework
• Open circuit voltage