Organic Doping at Ultralow Concentrations
Organic Doping at Ultralow Concentrations
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DOI：
10.1002/adom.202100089
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发表时间：
2021-04-24
影响因子：
9
通讯作者：
Lussem, Bjorn
中科院分区：
文献类型：
--
作者：
Krishnan, Raj Kishen Radha;Liu, Shiyi;Lussem, Bjorn
有机掺杂被广泛用于限定有机薄膜的多数电荷载流子、调节费米能级以及改善和稳定有机发光二极管和有机太阳能电池的性能。然而，与无机半导体相比，通常使用的掺杂浓度相当高（在wt%范围内）。这样的高浓度不仅限制了有机场效应晶体管（OFFET）中的掺杂范围，而且限制了掺杂过程本身，导致低掺杂效率。在这里，在超低掺杂浓度的掺杂机制进行了研究。掺杂的C-60金属氧化物半导体（MOS）结用于研究100 ppm水平的掺杂。借助小信号漂移扩散模型，可以将栅介质/有机半导体界面的陷阱效应与掺杂效应分离开来，并确定掺杂过程的掺杂效率和激活能。实现了具有800 mV超低工作电压和高达10（7）的优良开/关比的掺杂C-60 OFFET。该器件具有80 mV dec（-1）范围内的低亚阈值摆幅和高达8 mS mm（-1）的大摆幅。
Organic doping is widely used for defining the majority charge carriers of organic thin films, tuning the Fermi level, and improving and stabilizing the performance of organic light-emitting diodes and organic solar cells. However, in contrast to inorganic semiconductors, the doping concentrations commonly used are quite high (in the wt% range). Such high concentrations not only limit the scope of doping in organic field-effect transistors (OFETs), but also limit the doping process itself resulting in a low doping efficiency. Here, the mechanism of doping at ultralow doping concentrations is studied. Doped C-60 metal-oxide-semiconductor (MOS) junctions are used to study doping at the 100 ppm level. With the help of a small-signal drift-diffusion model, it is possible to disentangle effects of traps at the gate dielectric/organic semiconductor interface from effects of doping and to determine the doping efficiency and activation energy of the doping process. Doped C-60 OFETs with an ultralow operation voltage of 800 mV and an excellent on/off ratio of up to 10(7) are realized. The devices have low subthreshold swing in the range of 80 mV dec(-1) and a large transconductance of up to 8 mS mm(-1).