Optimization of MEH-PPV based single and double-layer TOLED structure by numerical simulation

In this work, we simulated and characterized Poly [2-methoxy-5-(2’-ethylhexyloxy)-1, 4-phenylene vinylene] (MEH-PPV) based single and double-layer TOLED by using Silvaco ATLAS device simulator to achieve prominent values of electrical and optical properties of the device. MEH-PPV were used as the emitting layer (EML) in the single-layer, while addition of Poly [(3,4-ethylene dioxythiophene)-poly(styrene sulfonate)] (PEDOT-PSS) as the electron transport layer (ETL) were conducted in double-layer TOLED simulation. The EML and ETL thickness in both structures were varied between 10 – 150 nm, respectively, to observe and understand the underlying physics of the relation in the layer thickness to the electrical and optical characteristics. Furthermore, variation of the EML/ETL thickness ratio from 1:1 to 5:1 (with thickness in between 10 to 50 nm) had also been conducted. From this work, it is understood that the thickness of the EML layer plays the most important role in TOLED, and by balancing the carrier injections and recombination rate in appropriate EML/ETL thickness ratio, the electrical and optical properties can be improved. By optimizing the EML/ETL thickness and thickness ratio, an optimal forward current of 1.41 mA and luminescent power of 1.93e-18 W/μm has been achieved with both MEH-PPV and PEDOT-PSS layer thickness of 10 nm (1:1 ratio), respectively. The results from this work will assist the improvement of TOLED device to be implemented widely in low power and transparent electronic appliances.