Unveiling a Realm of Possibilities in the Field of Material Science

Dr Sabyasachi Mukhopadhyay, Associate Professor in the Department of Physics at SRM University-AP recently published a paper, titled “Polarity-Induced Morphological Transformation with Tunable Optical Output of Terpyridine–Phenanthro[9,10-d] imidazole-Based Ligand and Its Zn(II) Complexes with I–V Characteristics,” in the prestigious journal “ACS Omega.” Notably, “ACS Omega” is a Q1 journal with an impact factor of 4.1. This groundbreaking work delves into the polarity-induced morphological transformations and tunable optical outputs of Terpyridine–Phenanthro[9,10-d] imidazole-based ligands and their Zn(II) complexes. The study also explores their I–V characteristics, contributing valuable insights to the realms of materials science and chemistry.


Self-assembled nanostructures obtained from various functional π-conjugated organic molecules have been able to draw substantial interest due to their inherent optical properties, which are imperative for developing optoelectronic devices, multiple-color-emitting devices with color-tunable displays, and optical sensors. These π-conjugated molecules have proven their potential employment in various organic electronic applications. Therefore, the stimuli-responsive fabrication of these π-conjugated systems into a well-ordered assembly is extremely crucial to tuning their inherent optical properties for improved performance in organic electronic applications.

To this end, herein, we have designed and synthesized a functional π-conjugated molecule (TP) having phenanthrol [9,10-d] imidazole with terpyridine substitution at the 2 position and its corresponding metal complexes (TPZn and (TP)2Zn). By varying the polarity of the self-assembly medium, TP, TPZn, and (TP)2Zn are fabricated into well-ordered superstructures with morphological individualities. However, this medium polarity-induced self-assembly can tune the inherent optical properties of TP, TPZn, and (TP)2Zn and generate multiple fluorescence colors.

Particularly, this property makes them useful for organic electronic applications, which require adjustable luminescence output. More importantly, in a 10% aqueous-THF medium, TPZn exhibited H-type aggregation-induced white light emission and behaved as a single-component white light emitter. The experimentally obtained results of the solvent polarity-induced variation in optical properties as well as self-assembly patterns were further confirmed by theoretical investigation using density functional theory calculations. Furthermore, we investigated the I− V characteristics, both vertical and horizontal, using ITO and glass surfaces coated with TP, TPZn, and (TP)2Zn, respectively, and displayed maximum current density for the TPZn-coated surface with the order of measured current density TPZn > TP > (TP)2Zn.

This observed order of current density measurements was also supported by a direct band gap calculation associated with the frontier molecular orbitals using the Tauc plot. Hence, solvent polarity-induced self-assembly behavior with adjustable luminescence output and superior I−V characteristics of TPZn make it an exceptional candidate for organic electronic applications and electronic device fabrication.

Research Explanation

Our investigation is based on the electron transport characteristics of molecules (voltage vs. current), which allows us to ascertain the molecule’s conductive capacities. The Janis probe station, which has four gold tips total is the primary instrument utilized in this investigation. To investigate the properties of electron transport, two gold tips were used: one in contact with an aluminum electrode and the other with an ITO surface. The current measurements for a given voltage of given molecules have been studied using a source measuring unit.


  • Our research study can be applicable to predict the good electron and hole transport layers for the Organic Light Emitting Diode (OLED) application.
  • Organic field effect transistor (OFET) applications.


Dr. Priyadip Das, Associate Professor, Department of Chemistry,SRMIST

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