Georgiopoulou Zoi, Verykios Apostolis, Ladomenou Kalliopi, Maskanaki Katerina, Chatzigiannakis Georgios, Armadorou Konstantina-Kalliopi, Palilis Leonidas C, Chroneos Alexander, Evangelou Evangelos K, Gardelis Spiros, Yusoff Abd Rashid Bin Mohd, Coutsolelos Athanassios G, Aidinis Konstantinos, Vasilopoulou Maria, Soultati Anastasia
Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research Demokritos, Agia Paraskevi, 15341 Athens, Greece.
Solid State Physics Section, Physics Department, National and Kapodistrian University of Athens, Panepistimioupolis, Zografos, 15784 Athens, Greece.
Nanomaterials (Basel). 2022 Dec 30;13(1):169. doi: 10.3390/nano13010169.
Charge injection and transport interlayers play a crucial role in many classes of optoelectronics, including organic and perovskite ones. Here, we demonstrate the beneficial role of carbon nanodots, both pristine and nitrogen-functionalized, as electron transport materials in organic light emitting diodes (OLEDs) and organic solar cells (OSCs). Pristine (referred to as C-dots) and nitrogen-functionalized (referred to as NC-dots) carbon dots are systematically studied regarding their properties by using cyclic voltammetry, Fourier-transform infrared (FTIR) and UV-Vis absorption spectroscopy in order to reveal their energetic alignment and possible interaction with the organic semiconductor's emissive layer. Atomic force microscopy unravels the ultra-thin nature of the interlayers. They are next applied as interlayers between an Al metal cathode and a conventional green-yellow copolymer-in particular, (poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1',3}-thiadiazole)], F8BT)-used as an emissive layer in fluorescent OLEDs. Electrical measurements indicate that both the C-dot- and NC-dot-based OLED devices present significant improvements in their current and luminescent characteristics, mainly due to a decrease in electron injection barrier. Both C-dots and NC-dots are also used as cathode interfacial layers in OSCs with an inverted architecture. An increase of nearly 10% in power conversion efficiency (PCE) for the devices using the C-dots and NC-dots compared to the reference one is achieved. The application of low-cost solution-processed materials in OLEDs and OSCs may contribute to their wide implementation in large-area applications.
电荷注入和传输层在包括有机和钙钛矿型在内的许多类光电器件中起着至关重要的作用。在此，我们展示了原始的和氮功能化的碳纳米点作为电子传输材料在有机发光二极管（OLED）和有机太阳能电池（OSC）中的有益作用。通过循环伏安法、傅里叶变换红外（FTIR）和紫外可见吸收光谱系统地研究了原始的（称为C点）和氮功能化的（称为NC点）碳纳米点的性质，以揭示它们的能级排列以及与有机半导体发射层可能的相互作用。原子力显微镜揭示了这些层的超薄性质。接下来，它们被用作铝金属阴极和传统黄绿共聚物之间的层，特别是（聚[(9,9-二辛基芴-2,7-二基)-alt-共-(1,4-苯并-{2,1',3}-噻二唑)]，F8BT），用作荧光OLED中的发射层。电学测量表明，基于C点和NC点的OLED器件在电流和发光特性方面都有显著改善，主要是由于电子注入势垒的降低。C点和NC点还被用作具有倒置结构的OSC中的阴极界面层。与参考器件相比，使用C点和NC点的器件的功率转换效率（PCE）提高了近10%。在OLED和OSC中应用低成本的溶液处理材料可能有助于它们在大面积应用中的广泛实施。
