Exploring the photovoltaic properties of naphthalene-1,5-diamine-based functionalized materials in aprotic polar medium: a combined experimental and DFT approach

Abstract

In this study, a series of naphthalene-1,5-diamine-based donor chromophores (ND1–ND9) with A–D–A architecture was synthesized through a condensation reaction between amines and substituted aldehydes. Various spectroscopic techniques i.e., FTIR, UV-Vis, ¹HNMR and ¹³CNMR were performed for structural elucidation of naphthalene-1,5-diamine-based chromophores. Accompanying the synthesis, quantum chemical calculations were also accomplished at MPW1PW91/6-311G (d,p) functional of DFT/TD-DFT approaches to explore the photovoltaic properties of ND1–ND9 compounds. A comparative study between experimental and DFT results of vibrational and UV-Vis analyses showed a good harmony. All compounds showed band gaps in the range of 3.804–3.900 eV with absorption spectra in the UV region (397.169–408.822 nm). Frontier molecular orbital (FMO) findings revealed an efficient intramolecular charge transfer (ICT) from the central naphthalene-1,5-diamine-based donor core towards terminal acceptors. This significant charge transfer was also supported by the density of states (DOS) and transition density matrix (TDM) maps. All synthesized chromophores showed lower exciton binding energy values (E_b = 0.670–0.785 eV), illustrating higher exciton dissociation rates with greater charge transfer in the studied chromophores. A reasonable harmony was obtained by comparative investigations of a standard hole transport material (HTM), Spiro-OMe TAD, with ND1–ND9 compounds, which illustrated that these synthesized chromophores might be considered as good HTMs. Therefore, all analyses indicated that the naphthalene-1,5-diamine-based chromophores might be utilized as efficient photovoltaic materials.