Research Projects

Now-a-days, light emitting diodes (LEDs) based on conjugated polymers have been attracted great attention by the scientists as well as technologists due to their potential applications in field of displays and solid-state light emitting material and owing to the advantage of ease of synthesis and purity, relatively higher thermal stability, good film forming properties, color tunability, low-cost etc. However, these optoelectronic devices, such as light-emitting diodes (LEDs), organic solid-state lasers, and fluorescent sensors desire intrinsically the emission of visible light in the solid-state or film state and these should have few characteristics like low power consumption, rapid response, mechanical flexibility, light weight and cost-effective and environment friendly. Though, most organic derivatives are highly emissive in solution-phase or in presence of solvent, these suffer considerable quenching of emission owing to the strong intermolecular interactions (H-bonding, π-π, van der Waals, etc.) in the compactly aggregated state or film. To avoid this kind of aggregation that causes weakly emission or non-emissive quenching, buta-1,3-diene core has been judiciously picked up to achieve the emission in the solid-state by inhibiting intermolecular interaction. By inserting functional group on buta-1,3-diene core to achieve color-tunability from blue to red and variations of quantum yields have been achieved. Several buta-1,3-diene core of mono-, oligo- and copolymers have been developed and optical properties have investigated in our laboratory. It has been already observed that prepare derivatives are emissive in nature both in solution and the film state with the interplay between locally excited (LE) state and charge transfer (CT) excited state by inserting donor-acceptor group on buta-1,3-diene moiety. Particularly, conjugated polymers frequently suffer insufficient energy transfer from CT to LE (termed as HLCT excited state: hybrid and local charge transfer), lowering performance in the device. From the results of solvato-chromic experiment of buta-1,3-diene derivatives and the subsequent dipole moment calculation using Lippert-Mataga model have showed that these derivatives have medium dipole moment values in low to medium polarity of solvents indicating coexistence of both LE and CT state whereas in high polarity environment very high excited state dipole moment indicates either pure CT or CT dominant excited state is formed. To the best of my knowledge, buta-1,3-diene based small molecules, oligo- and polymers are never applied before as emissive layer in light emitting diodes (LEDs). Considering all these things in mind, it has been planned as well as proposed to fabricate as well as develop light emitting devices made of buta-1,3-diene moieties and proto-type device will be developed in the laboratory scale.