Highly Efficient Organic Light Emitting Devices Based On New Iridium Compounds

Organic light-emitting diodes(OLEDs) played an important role in the next generation of lighting and display technology for its superior performance. And the development of high-performance phosphorescent materials is an important way to improve the performance of OLEDs. This paper designed and synthesized two efficient iridium compounds, investigated the optics and electricity performances of the two materials. Then we utilized those compounds in vacuum evaporation and spin coating and demonstrated a series of high performance monochrome and white OLEDs.1. Designed and synthesized new yellowish green iridium compound Ir(ppy)2bop and investigated the photophysics and electrical characteristics of the material and yellowish green device based on the compound. The results showed that Ir(ppy)2bop owned a high fluorescent quantum yield of 0.3 and a yellowish green emission of 526 nm. Monochrome phosphorescent device fabricating by vacuum evaporation showed maximum efficiency of 43.3 cd/A(18.1%) with the emission peak of 538 nm, the result among the best of report green/yellowish green devices. Furthermore, the yellowish green device using spin coating process obtained the maximum efficiency of 17.8 cd/A(9.1%).2. Designed and synthesized new red iridium compound Ir(piq)2bop and investigated the photophysics and electrical characteristics of the material and red device based on the compound. Ir(piq)2bop showed red emission with the emission peak of 614 nm and half with at half-maximum(HWHM) of 55 nm. Red phosphorescent device using vacuum evaporation process showed the emission peak of 623 nm and CIE coordinates of(0.67, 0.33), the obtained maximum efficiency of the device is 7.2 cd/A(8.5%). Besides, the monochrome device using spin coating process showed great homogeneity and good performance.3. A series of high performance fluorescence/phosphorescence(F/P) white OLED have been fabricated and investigated. The device using DPF as blue fluorescence, Ir(ppy)2bop and Ir(piq)3 respectively as yellowish-green and red phosphorescence showed high efficiencies of 55.2 cd/A, 49.6 lm/W and 20%, it is noteworthy that the color rending index(CRI) of the device reached up 89, the CIE coordinates was measured to be(0.38, 0.46). The results of the device are among the best of recently reported F/P white OLEDs. Besides, The white OLED using DPF, Ir(ppy)2bop and deep-red phosphorescence Ir(piq)2bop also shows great performance. The device achieved high efficiencies of 44.2 cd/A, 39.6 lm/W and 16.1%, maximum CRI of 81 and CIE of(0.41, 0.49).The results of the paper enriched the selectivity of phosphorescent materials, and promoted the development of white OLEDs.