Gaul Christopher, Hutsch Sebastian, Schwarze Martin, Schellhammer Karl Sebastian, Bussolotti Fabio, Kera Satoshi, Cuniberti Gianaurelio, Leo Karl, Ortmann Frank
Center for Advancing Electronics Dresden and Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany.
Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Dresden, Germany.
Nat Mater. 2018 May;17(5):439-444. doi: 10.1038/s41563-018-0030-8. Epub 2018 Feb 26.
Doping plays a crucial role in semiconductor physics, with n-doping being controlled by the ionization energy of the impurity relative to the conduction band edge. In organic semiconductors, efficient doping is dominated by various effects that are currently not well understood. Here, we simulate and experimentally measure, with direct and inverse photoemission spectroscopy, the density of states and the Fermi level position of the prototypical materials C and zinc phthalocyanine n-doped with highly efficient benzimidazoline radicals (2-Cyc-DMBI). We study the role of doping-induced gap states, and, in particular, of the difference Δ between the electron affinity of the undoped material and the ionization potential of its doped counterpart. We show that this parameter is critical for the generation of free carriers and influences the conductivity of the doped films. Tuning of Δ may provide alternative strategies to optimize the electronic properties of organic semiconductors.
掺杂在半导体物理学中起着至关重要的作用，n型掺杂由杂质相对于导带边缘的电离能控制。在有机半导体中，高效掺杂受多种目前尚未完全理解的效应主导。在此，我们利用直接和逆光电子能谱模拟并通过实验测量了用高效苯并咪唑啉自由基（2-Cyc-DMBI）进行n型掺杂的典型材料C和酞菁锌的态密度及费米能级位置。我们研究了掺杂诱导的能隙态的作用，特别是未掺杂材料的电子亲和能与其掺杂对应物的电离势之间的差值Δ的作用。我们表明，该参数对于自由载流子的产生至关重要，并影响掺杂薄膜的电导率。调整Δ可能会提供优化有机半导体电子性能的替代策略。
