| Summary: | 博士 國立清華大學 化學系 近年來，一些磷光有機金屬被大家所青睞，他們可以廣泛地應用在多方面，例如：OLED的發光層、太陽能電池，甚至氧的偵測，這些材料包含了d8電子組態的Pt(II)、Au(II)與d6電子組態的Re(I)、Os(II)、Ru(II)、Ir(III)和Pt(IV)，這些材料通常具有較穩定的激態與高的量子效率，也由於具有強的重原子效應，繼而增強他們的磷光，尤其對於第三列的過度金屬，由於他們的dd能階較高，與最低放光的能階相差較大，不太會影響到磷光的放光，因此在室溫下通常擁有較強的磷光發光性質，這對於應用在OLED的材料上是相當好的優點。 我們可以利用簡單的方法，從Os3(CO)12直接跟我們的配位基，例如3-trifluoromethyl-5-(2-pyridyl)triazole（fttz），反應生成[Os(CO)2(fttz)2]，這類型的化合物具有很強的藍色磷光，並且當我們改變配位基的官能團，還可以改變這些化合物放光的位置，繼而達到更純的光色；而這類型的化合物我們利用 phosphine 取代CO，調整其HOMO ? LUMO的能階差的高低，我們進一步可以得到較低能量的光：綠光、黃光、橘光，甚至純紅色的光，這些都可以經由我們對取代基控制，得到很好的結果。 Abstract: 1. Os(II) blue emitters: A new series of Os(II) based complexes [Os(CO)2(py-tBu-tz)2] (1), [Os(py-tBu-tz)2(CO)2] (2) and [Os(py-CF3 -tz)2(CO)2] (3), in which bptz and fptz denote 3-t-butyl-(2-pyridyl) and 3-trifluoromethyl-5-(2-pyridyl) 1,2,4-triazolate, respectively, were synthesized in an aim to attain high efficiency room temperature blue phosphorescence. Although 1 and 2 are both geometric isomers, drastically different excited-state relaxation pathways were resolved. 1 exhibits strong phosphoresce (?p ~ 0.47) in CH3CN as well as in a single crystal, while 2 is nearly non-emissive. The associated relaxation dynamics have been investigated comprehensively from spectroscopy, dynamics and theoretical approaches. Our results lead to a conclusion that the trans effect imposed by the CO ligand plays a crucial role in fine-tuning the relative energy gap between the lowest 3??* state and the metal centered dd state, which then triggers fast radiationless deactivation for the geometrical isomer 2. Fine adjustment is also achieved by functionalizing the ligands so that the electron withdrawing property of the CF3 group in 3 not only stabilizes the HOMO of the triazolate moiety, but also greatly enhances the ?-acid nature of the ligand. Consequently, the ??* gap of ligand is increased and the d orbitals of the Os atom are stabilized by the enhanced metal-to-ligand back bonding, resulting in a highly efficient phosphorescence suited to application as a blue OLED emitter. 2. Os(II) red emitters: The OLED device using 6% of Os(py-CF3 -tz)2(PPh2Me)2 as the dopant emitter in CBP host and BPAPF as HTL shows an external quantum efficiency of 15.3% and luminous efficiency of 21.3 cd/A, power efficiency of 6.3 lm/W at 20 mA/cm2. An even higher external quantum efficiency of ~20 % was achieved at low current density of ~1 mA/cm2. 3. Ru(II) red emitters: The preparation of three charge neutral Ru(II) isoquinoline pyrazolate complexes, [Ru(ipy-tBu-pz)2(PPhMe2)2] (1) [Ru(ipy-tBu-pz)2(PPh2Me)2] (2) and [Ru(ipy-CF3 -pz)2(PPh2Me)2] (3) (ibpz: 3-tert-butyl-5-(1-isoquinolyl) pyrazolate, ifpz: 3-trimethylfluoro-5- (1-isoquinolyl) pyrazolate), is reported. An OLED device using 24 wt.% of 3 as a dopant emitter in 1,4-bis(N-carbazolyl) biphenyl host material and with 1,4-bis(1-naphylphenylamino) biphenyl as hole transport layer exhibits saturated red phosphorescence with an external quantum efficiency of 4.44%, luminous efficiency of 5.08 cd/A and power efficiency of 2.36 lm/W at the applied current density of 20 mA/cm2.
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