Light regulation of organic light emitting diodes with conductive distributed Bragg reflectors

Yun Hu, Jing-song Huang, Paul Stavrinou, Donal D. C. Bradley

Proc. of SPIE Vol. 12314 123140O-2, 2023

Non-metallic mirror, such as semiconductor distributed Bragg reflectors (DBRs), has been widely integrated in the structure of optoelectronic devices.

However, constructing conductive DBR in organic optoelectronic device is still scarce, because of the incompatibility of high-temperature processes in the preparation of inorganic DBR.

Herein, it is confirmed that organic-oxide hybrid DBR can achieve high conductivity and light manipulation. When thermal evaporated material MoO3 is doped into organic material (1,1-bis[4-[N,N-di(p-tolyl)amino]phenyl]cyclohexane, TAPC), the conductivity of TAPC can be increased by ten thousand times with very small refractive index change.

It is shown that 8.5 pairs DBR at 460 nm has a reflectivity of about 95%, and the driving voltage is 8.2 V at the current density of 100 mA cm-2. Then, a transparent organic light-emitting diode with integrated bottom conductive DBR are fabricated to confirm the functionality of light regulation.

The results confirm that integrated optoelectronic devices with DBR as reflector can be achieved with low operating voltage.

The optical simulations of DBR and OLED devices were performed by using a commercially available SETFOS (Fluxim) software. The refractive index, extinction coefficient (k), photoluminescence (PL) spectrum of emissive layers and thickness of each layer were used as input parameters. Transfer matrix method (TMM) and Gaussian dipole distribution dipole emitter as source are used in simulation.