A new single crystal of 4-(diphenylamino)benzaldehyde-4-(methyl)thiosemicarbazone, featuring a D-π-D molecular template was synthesized and utilized as an additive in solid biopolymer electrolytes mixed with carboxymethyl cellulose (CMC) and propylene carbonate (PC). The additive was structurally characterized using single-crystal X-ray diffraction. This revealed a triclinic crystal structure belonging to the triclinic space group, P− 1 . The lattice parameters were determined as follows: a = 6.942(6) Å; b = 11.409(11) Å; c = 12.442(10) Å; α= 91.024(16)◦; β= 104.264(12)◦; γ= 107.496(12)◦; V= 906.4(13)Å3 and Z= 2. Notably, the additive exhibited extensive π-electron delocalization, leading to the formation of infinite chains through C-H-π interactions and intermolecular hydrogen bonding, ultimately resulting in an inverse centrosymmetric dimer in the form of the R2 2(8) motif. Furthermore, a detailed Hirshfeld surface analysis of the additive revealed significant contributions from C⋅⋅⋅H/ H⋅⋅⋅C, H⋅⋅⋅S/S⋅⋅⋅H and H⋅⋅⋅N/ N⋅⋅⋅H interactions with 20.7%, 11.2% and 3.7% of the total Hirshfeld surface analysis, respectively. These interactions indicate the potential of the additive to facilitate efficient electron transfer processes. The conductivity (σ) of the CMC–PC–additive system determined at ambient temperature was 8.00 ×10− 9 Scm− 1. The dielectric properties showed that the system follows the non-Debye behavior, in which the conductivity is predominantly due to ion conduction via the hopping mechanism.