Optimization of NPD/Alq3/TPBi/Bphen OLED structure and investigation of electrical characteristics along with allied parameters

摘要

Abstract Motivated form the performance and utilization of organic light emitting diodes (OLEDs) in advanced flexible optoelectronic devices, this research article reports the structure optimization of ITO/NPD/Alq3/TPBi/Bphen/LiF/Al based OLED. For the designed OLED, the computational investigation of its electrical properties (charge densities, I–V and J–V characteristics), recombination rates along the growth direction and optical parameters with the help of Shockley–Read–Hall recombination model, Poisson equations, drift and diffusion equations and carrier continuity equation have been studied. As per the data taken from the I–V and J–V characteristics, the operating (threshold) voltage of designed OLED was found as ~ 3.5 V. From the calculation, it was confirmed that the e–h recombination rate is highest (~ 4.5 × 1028/m3) in emissive (EML) region (~ 260 nm–275 nm). In optical parameters, the study has been made on input emission spectrum of the emissive (EML) layer (Alq3) which demonstrates the maximum intensity corresponding to wavelength of ~ 475 nm (visible region). Further, the external quantum efficiency with variable applied voltage has also been studied with the information on the mechanism of efficiency drop on a particular voltage. The behaviours of the recombination prefactors β1 and β2 for the designed OLED have also been studied with the variable applied range of voltages. The outcomes of the study suggest the usage of optimized OLED structure in the advanced and flexible optoelectronics in the visible region.