Emission color tuning in organic light emitting diodes (OLEDs) via multi-step spin-coating program

The compound [Pb₂(PhN₂O₂)₄] was synthesized and utilized as luminescent materials in organic light-emitting diodes (OLEDs). The Förster energy transfer radius, photoluminescent, quantum yield, and absorbance have been investigated. We have introduced a new multi-step spin-coating program to control the electron transport properties and luminescence efficiency of the OLED device. Results show that using a device with a multi-step spin-coating program [3000 rpm → 1500 rpm → 3000 rpm → 1500 rpm → 3000 rpm], may increase electroluminescence and the emission carrier recombination rate in the device; also a white emission was achieved. The white emission which was composed of blue, green, and red emission peaks related to the electroplex emission and deposition rate of the complex, respectively. By following this step, we investigated the effect of the multi-step spin-coating program on the electron mobility of devices with the space-charge-limited current (SCLC) method. A device with a fundamental structure of ITO/ [Pb₂(PhN₂O₂)₄]/LiF(1 nm)/Al (180 nm) was fabricated, and its electron mobility at various thicknesses of the emitting layer (EML) has been investigated. It is shown that the multi-step spin-coating program is a promising candidate for the fabrication of high luminescence efficiency and wavelength-tunable OLEDs.