Tsuboyama Akira, Kuge Katsuaki, Furugori Manabu, Okada Shinjiro, Hoshino Mikio, Ueno Kazunori
Leading-Edge Technology Development Headquarters, Canon Incorporated, Ohta-ku, Tokyo 146-8501, Japan.
Inorg Chem. 2007 Mar 19;46(6):1992-2001. doi: 10.1021/ic0608086. Epub 2007 Feb 27.
Studies on synthesis, structures, and photophysics have been carried out for a series of luminescent copper(I) halide complexes with the chelating ligand, 1,2-bis[diphenylphosphino]benzene (dppb). The complexes studied are halogen-bridged dinuclear complexes, [Cu(mu-X)dppb]2 (X = I (1), Br (2), Cl (3)), and a mononuclear complex, CuI(dppb)(PPh3) (4). These complexes in the solid state exhibit intense blue-green photoluminescence with microsecond lifetimes (emission peaks, lambdamax = 492-533 nm; quantum yields, Phi = 0.6-0.8; and lifetimes, tau = 4.0-10.4 mus) at 298 K. In 2-methyltetrahydrofuran (2mTHF) solutions at 298 K, only 1 and 4 show weaker emission (Phi = 0.009) with shorter lifetimes (tau = 0.35 and 0.23 mus) and red-shifted spectra (lambdamax = 543 and 546 nm). The emission in the solid state originates from the (M + X)LCT excited state with a distorted-tetrahedral conformation, in which emissive excited states, 1(M + X)LCT and 3(M + X)LCT, are in equilibrium with an energy difference of approximately 2 kcal/mol. On the other hand, the complexes in the 2mTHF solutions emit from the MLCT excited state with an energetically favorable flattened conformation in the temperature range of 298-130 K. The flattened geometry with equilibrated 1MLCT and 3MLCT states has a nonradiative rate at least 2 orders of magnitude larger than that of the distorted-tetrahedral geometry, leading to a much smaller emission quantum yield (Phi = 0.009) at 298 K. Since the flattening motion is markedly suppressed below 130 K, the emission observed in 2mTHF below 130 K is considered to occur principally from the (M + X)LCT state with a distorted-tetrahedral geometry. To interpret the photophysics of 1 and 4 in both the solid and solution states, we have proposed the "2-conformations with 2-spin-states model (2C x 2S model)". The electroluminescence device using (1) as a green emissive dopant showed a moderate EL efficiency; luminous efficiency = 10.4 cd/A, power efficiency = 4.2 lm/W at 93 cd/m(2), and maximum external quantum efficiency = 4.8%.
对一系列含有螯合配体1,2 - 双[二苯基膦基]苯（dppb）的发光卤化亚铜配合物进行了合成、结构和光物理研究。所研究的配合物包括卤素桥连的双核配合物[Cu(μ - X)dppb]₂（X = I (1)、Br (2)、Cl (3)）以及单核配合物CuI(dppb)(PPh₃) (4)。这些配合物在固态时于298 K呈现强烈的蓝绿色光致发光，寿命为微秒级（发射峰，λmax = 492 - 533 nm；量子产率，Φ = 0.6 - 0.8；寿命，τ = 4.0 - 10.4 μs）。在298 K的2 - 甲基四氢呋喃（2mTHF）溶液中，只有1和4显示较弱的发射（Φ = 0.009），寿命较短（τ = 0.35和0.23 μs）且光谱红移（λmax = 543和546 nm）。固态中的发射源于具有扭曲四面体构象的(M + X)LCT激发态，其中发光激发态¹(M + X)LCT和³(M + X)LCT处于平衡，能量差约为2 kcal/mol。另一方面，2mTHF溶液中的配合物在298 - 130 K温度范围内从具有能量有利的扁平构象的MLCT激发态发射。具有平衡的¹MLCT和³MLCT态的扁平几何结构的非辐射速率比扭曲四面体几何结构至少大2个数量级，导致在298 K时发射量子产率小得多（Φ = 0.009）。由于扁平运动在130 K以下被显著抑制，在130 K以下的2mTHF中观察到的发射主要被认为来自具有扭曲四面体几何结构的(M + X)LCT态。为了解释1和4在固态和溶液态中的光物理性质，我们提出了“2 - 构象与2 - 自旋态模型（2C×2S模型）”。使用(1)作为绿色发光掺杂剂的电致发光器件显示出中等的EL效率；在93 cd/m²时发光效率 = 10.4 cd/A，功率效率 = 4.2 lm/W，最大外量子效率 = 4.8%。
