A combined DFT and experimental study into the optoelectronic and charge transport properties of ninhydrin–glycine Schiff base complexes for efficient LED applications

A combined theoretical and experimental study has been performed on four synthesized Schiff base complexes derived from ninhydrin–glycine ligand (NG) with Co(II), Zn(II), Al(III) and Fe(III) metal cations. The FT-IR spectra clearly showed that the complexes behave as tridentate monobasic ONO donor ligand. Furthermore, the energy levels of HOMO, LUMO levels and band gap were determined using the Density Functional Theory (DFT). The experimental and theoretical optical investigation showed that the complexes have good absorption in visible region and blue emission with a maximum emission wavelength located at 436 nm, 471 nm and 478 nm for Co–NG, Zn–NG and Al–NG, respectively. Moreover, based on Marcus theories, we estimated the rate of electron and hole charge transfer. As a result, Al–NG complex has the better electron and hole transport than the other complexes with Ket = 4.10 × 1014 and Kht = 4.86 × 1014, respectively. Finally, to predict the possibility of introducing the studied complexes in light emitting diode (LED) devices, the electron and hole injection barriers were estimated. The found results are interesting which make the studied complexes potential candidates for LED application.