Moschetto Salvatore, Squeo Benedetta Maria, Reginato Francesco, Prosa Mario, Pasini Mariacecilia, Toffanin Stefano
Institute of Nanostructured Materials (ISMN), National Research Council (CNR), Via P. Gobetti 101, 40129 Bologna, Italy.
Institute of Chemical Sciences and Technologies "G. Natta" (SCITEC), National Research Council (CNR), via Corti 12, 20133 Milan, Italy.
Molecules. 2024 Jul 12;29(14):3295. doi: 10.3390/molecules29143295.
Ambipolar organic light-emitting transistors (OLETs) are extremely appealing devices for applications from sensing to communication and display realization due to their inherent capability of coupling switching and light-emitting features. However, their limited external quantum efficiency (EQE) and brightness under ambipolar bias conditions hamper the progress of OLET technology. In this context, it was recently demonstrated in multi-stacked devices that the engineering of the interface between the topmost electron-transporting organic semiconductor (e-OS) and the emission layer (EML) is crucial in optimizing the recombination of the minority charges (i.e., electrons) and to enhance EQE and brightness. Here, we introduce a new light-emitting conjugated polar polymer (CPP) in a multi-stacked OLET to improve the electron injection from e-OS to EML and to study, simultaneously, electroluminescence-related processes such as exciton formation and quenching processes. Interestingly, we observed that the highly polar groups present in the conjugate polymer induced polarization-related relevant charge-trapping phenomena with consequent modulation of the entire electrostatic field distribution and unexpected optoelectronic features. In view of the extensive use of CPPs in OLETs, the use of multifunctional CPPs for probing photophysical processes at the functional interfaces in stacked devices may speed up the improvement of the light-emission properties in OLETs.
双极型有机发光晶体管（OLETs）因其固有的开关和发光特性耦合能力，在从传感到通信及显示实现等应用中是极具吸引力的器件。然而，它们在双极偏置条件下有限的外量子效率（EQE）和亮度阻碍了OLET技术的发展。在此背景下，最近在多层器件中证明，最顶层电子传输有机半导体（e-OS）与发光层（EML）之间界面的工程设计对于优化少数载流子（即电子）的复合以及提高EQE和亮度至关重要。在这里，我们在多层OLET中引入一种新型发光共轭极性聚合物（CPP），以改善从e-OS到EML的电子注入，并同时研究与电致发光相关的过程，如激子形成和猝灭过程。有趣的是，我们观察到共轭聚合物中存在的高极性基团引发了与极化相关的电荷俘获现象，从而调制了整个静电场分布并产生了意想不到的光电特性。鉴于CPPs在OLETs中的广泛应用，使用多功能CPPs来探测堆叠器件中功能界面处的光物理过程可能会加速OLET发光性能的改善。
