Controlled p doping of the hole-transport molecular material N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine with tetrafluorotetracyanoquinodimethane
Controlled p doping of the hole-transport molecular material N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine with tetrafluorotetracyanoquinodimethane
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DOI：
10.1063/1.1577400
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发表时间：
2003-07-01
影响因子：
3.2
通讯作者：
Kahn, A
中科院分区：
文献类型：
--
作者：
Gao, WY;Kahn, A
利用直接和反向光电子能谱、接触电位差测量和原位电流-电压（I-V）测量研究了空穴传输有机分子材料N，N '-二苯基-N，N'-双（1-萘基）-1，1 '-联苯-4，4'-二胺（alpha-NPD）与四氰基醌二甲烷（F-4-TCNQ）的p型掺杂。α-NPD的电离能和F-4-TCNQ的电子亲和能之间的紧密匹配导致主体的最高占据分子轨道和掺杂剂的最低占据分子轨道之间的有效电荷转移。相对于未掺杂的薄膜，掺杂0.5%的薄膜中费米能级向价态方向移动了0.62 eV，并且在与Au的界面处形成了一个窄的空间电荷层（类似于60埃）。掺杂器件中的空穴注入由于穿过耗尽区的隧穿而增加了几个数量级。电离的α-NPD分子的大弛豫能限制了费米能级的移动，并最终限制了空穴注入。(C)2003年，美国物理学会。
We investigate p-type doping of the hole-transport organic molecular material N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (alpha-NPD) with tetrafluorotetracyanoquinodimethane (F-4-TCNQ) using direct and inverse photoemission spectroscopy, contact potential difference measurements, and in situ current-voltage (I-V) measurements. The close match between the ionization energy of alpha-NPD and the electron affinity of F-4-TCNQ leads to an efficient charge transfer between highest occupied molecular orbital of the host and lowest occupied molecular orbital of the dopant. The Fermi level moves down towards the valence states by 0.62 eV in the 0.5% doped film with respect to the undoped film, and a narrow space charge layer (similar to60 Angstrom) forms at the interface with Au. Hole injection in the doped devices increases by several orders of magnitude due to tunneling through the depletion region. The large relaxation energy of the ionized alpha-NPD molecule limits the movement of the Fermi level and, ultimately, the hole injection. (C) 2003 American Institute of Physics.