Fluorescence Interface Engineering of PEDOT: PSS-HTL and BPhen-ETL Layers in Alq₃-Based OLEDs for Biomedical
Ghazi Aman Nowsherwan1, Hafiz Muhammad Khubaib2, Muhammad Azhar2,3
1Centre of Excellence in Solid State Physics, University of the Punjab, Lahore, 54590, Pakistan. ghaziaman.pu@gmail.com.
Abstract:
In this research study, the effect of different electron transport layers (ETLs) and hole transport layers (HTLs) on the performance of aluminum quinolate (Alq₃)-based organic light-emitting diodes (OLEDs) was investigated. The research focused on material selection, interface optimization, and the tuning of parameters to enhance device performance. Oghmanano software was employed to analyze various electrical characteristics, including current-voltage (I-V), current density-voltage (J-V), photon flux-voltage (Φ-V), charge density-voltage (Qt-V), recombination rate-voltage (K-V), and photon flux-current (Φ-I) relationships for the initial modeled structure with the layer configuration indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS)/Alq₃/C₆₀/lithium fluoride (LiF)/aluminum (Al). The initial simulated structure exhibited performance parameters of turn-on voltage (Vk) = 2.5 V, current density (J) = 1.85 × 103 A cm- 2, photon flux (Φ) = 3.57 × 10- 7 W m- 2, charge density (Qt) = 1.65 × 1023 m- 3, and recombination rate (K) = 8.13 × 10- 16 m3 s- 1. Furthermore, the effects of varying the thicknesses of the emissive and charge conduction layers were studied to determine the optimal parameters for maximum performance. Among the examined materials, PEDOT: PSS as the HTL and bathophenanthroline (BPhen) as the ETL exhibited superior charge conduction and band alignment with Alq₃. The optimized simulated structure demonstrated improved parameters: Vk = 2.8 V, J = 2.63 × 103 A m- 2, Φ = 7.35 × 10-4 Wm- 2, Qt = 1.89 × 1023 m- 3, and K = 2.79 × 10- 16 m3 s- 1. These results suggest that the optimized OLED structure can serve as an effective alternative to conventional configurations for advanced optoelectronic applications in the visible spectrum. Moreover, the enhanced fluorescence efficiency and tunable visible emission of the optimized OLED structure highlight its potential for fluorescence-based biomedical applications such as bioimaging, biosensing, and photodynamic therapy.
