Tuning photoluminescence properties is of prime importance for designing efficient light emitting diode (LED) materials. Here, we perform a computational study on the effect of normal N-heterocyclic carbene (NHC) and abnormal mesoionic carbene (MIC) ligands on the photoluminescence properties of some Ir(III) complexes, which are very promising LED materials. We find MIC as the privileged ligand in designing triplet emitters. The strong σ-donating and moderate π-accepting properties of MIC render a lower access to the nonemissive triplet metal-centered state (³MC), resulting in lowering the nonradiative rate constant (k_nr) and correspondingly achieving higher quantum efficiency. We also demonstrate that the judicial choice of ancillary ligand can improve the efficiency of these materials even further. This quantum chemical investigation focuses on the importance of MIC as cyclometalating ligand and the substantial effects of ancillary ligands in controlling the color tuning and quantum efficiency for optoelectronic applications.

中文翻译：

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辅助配体在具有N杂环或中离子碳配体的Ir（III）配合物的颜色调节和量子效率中的重要作用：比较量子化学研究

调整光致发光特性对于设计高效的发光二极管（LED）材料至关重要。在这里，我们对正常的N杂环卡宾（NHC）和异常的中离子卡宾（MIC）配体对某些Ir（III）配合物的光致发光性能的影响进行了计算研究，这是非常有前途的LED材料。我们发现MIC是设计三重态发射极的优先配体。MIC的强σ供体和适度的π接受特性使进入非辐射三重态金属居中状态（³ MC）的可能性降低，从而降低了非辐射速率常数（k _nr），并因此获得更高的量子效率。我们还证明，辅助配体的司法选择可以进一步提高这些材料的效率。量子化学研究的重点是作为环金属化配体的MIC的重要性以及辅助配体在控制光电应用的颜色调节和量子效率中的重大作用。