Steidel Jakob, Michalsky Ina, Ajdari Mohsen, Kivala Milan, Tegeder Petra
Ruprecht-Karls-Universität Heidelberg, Physikalisch-Chemisches Institut, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
Ruprecht-Karls-Universität Heidelberg, Organisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
Phys Chem Chem Phys. 2024 Jun 12;26(23):16454-16458. doi: 10.1039/d4cp01713g.
Bridged triarylamines, so-called N-heterotriangulenes (N-HTAs) are promising organic semiconductors for applications in optoelectronic devices. Thereby the electronic structure at organic/metal interfaces and within thin films as well as the electronically excited states dynamics after optical excitation is essential for the performance of organic-molecule-based devices. Here, we investigated the energy level alignment and the excited state dynamics of a N-HTA derivative adsorbed on Au(111) by means of energy- and time-resolved two-photon photoemission spectroscopy. We quantitatively determined the energetic positions of several occupied and unoccupied molecular (transport levels) and excitonic states (optical gap) in detail. A transport gap of 3.20 eV and an optical gap of 2.58 eV is determined, resulting in an exciton binding energy of 0.62 eV. With the first time-resolved investigation on a N-HTA compound we gained insights into the exciton dynamics and resolved processes on the femtosecond to picosecond timescale.
桥连三芳基胺，即所谓的N-杂三角烯（N-HTAs），是用于光电器件应用的有前途的有机半导体。因此，有机/金属界面和薄膜内的电子结构以及光激发后的电子激发态动力学对于基于有机分子的器件性能至关重要。在这里，我们通过能量分辨和时间分辨双光子光电子能谱研究了吸附在Au(111)上的N-HTA衍生物的能级排列和激发态动力学。我们详细定量地确定了几个占据和未占据分子（传输能级）以及激子态（光学能隙）的能量位置。确定了3.20 eV的传输能隙和2.58 eV的光学能隙，导致激子结合能为0.62 eV。通过首次对N-HTA化合物进行时间分辨研究，我们深入了解了激子动力学，并解析了飞秒到皮秒时间尺度上的过程。
