Optoelectronically active luminescent valine-substituted perylene diimide: structure-property correlation via spectroscopic and density functional approaches

In literature, the applicability of solution-phase perylene diimides (PDIs) semiconductors are limited due to their restricted solubility in solvents. In contrast, we synthesized a highly soluble and novel valine-functionalized PDI derivative (perylene diimide diacid, PDIDA) whose optical and electrical properties were carefully assessed by experimental and density functional approaches. Notably, on valine substitution, the ultraviolet-visible absorption band centered at 524 nm was attributed to the predominant HOMO & x2794; LUMO electronic transition (weighing coefficient = 99 %). Interestingly, the nonuniform variation (W-shaped) in absorption energy for HOMO & x2794; LUMO electronic transition in PDIDA with solvent dielectric constant was experimentally witnessed. The latter was computationally attributed to the more S(1)stabilization over S(o)solvent stabilization, particularly in ethanol and dimethyl sulfoxide (DMSO). Furthermore, upon 525 nm excitation, the maximum fluorescence emission was observed at 533 nm with photoluminescence quantum yield as high as 0.77. Interestingly, similar to absorption studies, pronounced influence of solvent polarity was evident on the emission maximum particularly in ethanol and DMSO. Subsequently, electrochemical investigation proved that the PDIDA sustained the intrinsic n-type semiconductivity with a dielectric constant (epsilon(r)) 5, a current of 0.54 mA at 5 V, and an electrical conductivity of 1.88 x 10(-5)Sm(-1). Owing to the above remarkable properties of the synthesized PDIDA, it holds potential applications in photovoltaics, fluorescence-based detectors and n-type channel field effect transistors, and so forth.