Sobri, Muhammad Latifur Rochman, Willy Satrio Nugroho
This study establishes a robust strategy for tuning the optoelectronic properties of biomass-derived activated carbon (AC) by precisely regulating its degree of aromatization. Utilizing a blending method, cloves (CLO)—an organic precursor rich in phenolic and aromatic complexes—were integrated into the AC host matrix to engineer non-covalent π-π interfacial dynamics, thereby modulating the bandgap energy, Urbach energy, and key optical constants, including the optical transition index (m), refractive index (n), optical conductivity (σoptical), and extinction coefficient (k). The results demonstrate that the degree of aromatization dictates distinct performance trade-offs within the material framework. At lower degrees of aromatization, interfacial dynamics are governed by dominant Van der Waals forces. UV-Vis spectroscopy reveals a significant bathochromic (red) shift where the optical bandgap (Eg) narrows from 3.459 eV (pure AC) to 3.087 eV (AC:CLO 1:1), as determined by the Absorption Spectrum Fitting (ASF) method. This reduction in Eg is accompanied by an increase in the refractive index (up to 2.374) and optical conductivity, driven by enhanced π-electron delocalization and charge carrier mobility. Conversely, excessive aromatization promotes inter-ring repulsive forces that widen the interplanar spacing, resulting in a hypsochromic (blue) shift evidenced by the broadening of Eg back to 3.459 eV (AC:CLO 1:2) and a corresponding decrease in the refractive index to 2.283. Furthermore, incorporating cloves increases the Urbach energy (EU) from 0.497 eV to 0.577 eV, indicating a significant modulation of localized defect states within the bandgap. In conclusion, π-π interactions driven by controlled aromatization successfully modulate the resonance balance and inter-ring forces, enabling the precise tuning of biomass-derived carbon for advanced optoelectronic applications. © 2026 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanical Engineering of Fisheries, Politeknik Ahli Usaha Perikanan, Jakarta Selatan, 12520, Indonesia; Center of Energy for Society and Industry, Universitas Muhammadiyah Magelang, Magelang, 56172, Indonesia; Department of Mechanical Engineering, Universitas Brawijaya, Malang, 65145, Indonesia
