Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy ( IF 4.4 ) Pub Date : 2020-09-17 , DOI: 10.1016/j.saa.2020.118952 Mostafa Tavakoli , Hossein Ahmadvand , Mojtaba Alaei , Mohammad Amin Ranjbari
In this work, we present a computational study on 105 selected organic molecules in order to find suitable candidates for using as thermally activated delayed fluorescent (TADF) emitters in organic light emitting diodes (OLEDs), in the emission range of red light. Based on time-dependent density functional theory (TD-DFT) computations, three promising candidates were found, predicted to have low singlet-triplet splittings, lower than 0.06 eV, and TADF rates of 0.124, 0.154 and 0.231 1/μs. Then, using an experimental-theory calibration approach, the emission wavelength of the molecules were estimated to be 570, 476, and 623 nm, respectively. For the molecule whose emission wavelength (623 nm) is predicted to be in our desired range, we measured the photoluminescence (PL) spectrum and find out that its emission peak is within the predicted accuracy of the employed method. Moreover, we benchmarked the performance of density functional based tight-binding (DFTB) method for future screening works and find out that, this method is an efficient pre-screening tool, useful in searching for molecules with desired emission wavelengths.
中文翻译:
从头开始搜索有机发光二极管的有效红色热激活延迟荧光分子
在这项工作中,我们对105个选定的有机分子进行了计算研究,以便找到合适的候选物,以在红光的发射范围内用作有机发光二极管(OLED)中的热激活延迟荧光(TADF)发射器。根据时变密度泛函理论(TD-DFT)计算,发现了三个有希望的候选物,预测其单重态-三重态分裂低,低于0.06 eV,TADF速率为0.124、0.154和0.231 1 / μs。然后,使用实验理论校准方法,估计分子的发射波长分别为570 nm,476 nm和623 nm。对于预测其发射波长(623 nm)在我们期望范围内的分子,我们测量了光致发光(PL)光谱,发现其发射峰在所采用方法的预测精度范围内。此外,我们对未来筛选工作中基于密度泛函的紧密结合(DFTB)方法的性能进行了基准测试,发现该方法是一种有效的预筛选工具,可用于搜索具有所需发射波长的分子。