| Summary: | 碩士 === 元智大學 === 光電工程學系 === 102 === Organic light-emitting devices (OLEDs) have drawn intensive interest because of their potential applications for full-color display and solid-state lighting. During the course of development, OLED has gradually evolved from fluorescent to phosphorescent and from monochrome to full-color, which then demand the better designs of red-green-blue phosphors for display applications. Among them, blue-emitting phosphors are the most important constituent because of its highest excitation and emission energy. In the first part, a novel sky blue-emitting iridium complex which developed by Prof. Yun Chi’s group were used to construct highly efficient blue OLEDs. Through the architecture optimization , a double-emitting layer structure adopted to improve device performance. Furthermore, sky blue iridium complex Ir(1) was used to combine the red osmium complex [Os(bpftz)2(PPhMe2)2] for white phosphorescent OLEDs, which possesses a red/blue/red emitting layer architecture. The white OLEDs exhibited stable warm white emission with a CIE corrdinate of (0.406,0.351).
On the other hand, a emerging category of thermally activated delayed fluorescent (TADF) materials proposed by prof. C. Adachi caused a scientific sensation recently. Thus, TADF materials have been named as the third generation organic materials because of their inherent high efficiency and low cost. The critical feature of TADF materials is its small energy gap between singlet and triplet state, increasing the energy transfer of reverse intersystem crossing (RISC). In the second part, a novel TADF material, CzX, which developed by the Prof. Ken-Tsung Wong’s group was used to construct highly efficient green OLEDs. A simplified tri-layer architecture adopted for examining the optimized concentration. The maximum efficiencies of CzX-based OLEDs were achieving 16.3% (49.7 cd/A and 59.3 lm/W), demonstrating the superior properties of this newly developed TADF material.
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