Electrically Doped Research Articles

Molecular Interactions and Ordering in Electrically Doped Polymers: Blends of PBTTT and F4TCNQ

Identifying how small molecular acceptors pack with polymer donors in thin and thick (bulk) films is critical to understanding the nature of electrical doping by charge transfer. In this study, the...

Interfacial doping for efficient charge injection in organic semiconductors

AbstractInterfacial doping in organic semiconductors (OSs) is an important technique to achieve efficient organic electronic devices. In this paper, we discuss how the charge injection into an OS can be enhanced by the insertion of a thin interfacial layer or an electrically doped OS layer between an electrode and an undoped OS. We present that the vacuum level shift and Fermi level modification by the electrical doping is the origin of the efficient charge injection through a metal–organic junction and an organic–organic junction. Application to organic electronics such as organic light‐emitting diodes (OLEDs) and organic photovoltaics (OPVs) is briefly summarized.

Electrical doping is paving the way for the implementation of OLEDs in consumer electronics

AbstractThe great potential of organic light‐emitting diodes (OLEDs) to replace current display and lighting technologies is no longer questioned. Nevertheless, before large‐scale production can commence, considerable advances in the OLED technology are still necessary to satisfy the corresponding challenging requirements and to be competitive with firmly established alternative technologies. In this context, significant progress in diode performance, lifetime and stability is achieved by employing electrically doped charge‐transport layers. Thus, the so‐called PIN technology allows for an early, successful implementation of OLEDs in consumer applications.

Energy level alignment of electrically doped hole transport layers with transparent and conductive indium tin oxide and polymer anodes

Using ultraviolet photoemission spectroscopy, we investigated the energy level alignment at the interfaces of typical anodes used in organic electronics, indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), with the oligomeric hole transport material N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD), and studied the influence of electrical interface doping by the strong electron acceptor tetrafluoro tetracyanoquinodimethane (F4-TCNQ). The fundamentally different anode materials with work functions of 4.40eV (ITO) and 4.85eV (PEDOT:PSS) show different hole injection barriers, which also depend on the thickness of the F4-TCNQ interface dopant layer. PEDOT:PSS anodes exhibit a consistently lower hole injection barrier to MeO-TPD compared to ITO by 0.1eV. We attribute this low hole injection barrier to additional charge transfer reactions at the PEDOT:PSS/MeO-TPD interface. In contrast, the deposition of the electron acceptor at the interface helps significantly to lower the hole injection barrier for ITO anodes.

41.3: In-Line Deposition of High-Efficiency p-i-n Organic Light-Emitting Devices

OLED devices with electrically doped transport layers show low operating voltage, high efficiency and long lifetime. For the first time, this paper demonstrates that the concept of p- and n-type electrical doping can be applied under manufacturing conditions. It shows that handling of dopants, adjustment of doping concentrations, and preparation of p-i-n type OLED stacks is possible with the worldwide first vertical in-line set-up. An in-line-manufactured highly efficient RGB-OLED-system is presented.