文献类型：期刊文献

中文题名：激基复合物和非激基复合物中C545T薄层的发光机制

英文题名：The Emissive Mechanism of C545T Thin Layer at the Exciplex and Non-Exciplex Interfaces

作者：赵源[1];吕昭月[1];邓鉴[1];曾国庆[1]

机构：[1]华东理工大学理学院物理系,上海200237

年份：2020

卷号：40

期号：12

起止页码：3711

中文期刊名：光谱学与光谱分析

外文期刊名：Spectroscopy and Spectral Analysis

收录：CSTPCD;;EI(收录号：20205309699007);Scopus;WOS:【SCI-EXPANDED(收录号:WOS:000604865500010)】；北大核心:【北大核心2017】；CSCD:【CSCD2019_2020】；PubMed;

基金：国家自然科学基金项目(11504109);华东理工大学大学生创新训练项目(X18177)资助。

语种：中文

中文关键词：光致发光;C545T;能量传递;载流子捕获;激基复合物

外文关键词：Photoluminescence;C545T;Energy transfer;Carrier capture;Exciplex

摘要：研究了传统荧光材料香豆素C545T在激基复合物3DTAPBP/TPBi和非激基复合物CBP/TPBi体系中发光机制,器件结构为ITO/MoO3/3DTAPBP/C545T/TPBi/LiF/Al和ITO/MoO3/CBP/C545T/TPBi/LiF/Al。3DTAPBP, CBP和TPBi分别是有机材料2,2'-Bis(3-(N,N-di-p-tolylamino) phenyl) biphenyl, 4,4'-bis(N-carbazolyl)-2,2'-biphenyl, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl) benzene的简称。薄膜3DTAPBP, CBP和TPBi的光致发光峰分别为415, 411和380 nm;异质结薄膜3DTAPBP/TPBi的光致发光光谱有两个发光峰:412和490 nm, 412 nm的峰可认为是3DTAPBP的发光,但490 nm的发光既不来自3DTAPBP,也不来自TPBi,是3DTAPBP与TPBi界面形成激基复合物产生的发光;而异质结薄膜CBP/TPBi的光致发光光谱表现为CBP和TPBi发光的叠加,未产生新的发光峰,因此CBP/TPBi界面不能形成激基复合物。把C545T插入激基复合物3DTAPBP/TPBi和非激基复合物CBP/TPBi界面,器件的电致发光光谱表明发光主要来自C545T。器件中, C545T与其两侧的材料相互扩散,形成掺杂体系,即C545T与3DTAPBP、 TPBi,或与CBP、 TPBi形成掺杂体系,掺杂体系中客体发光机制通常有两种:主体与客体之间的能量传递和客体直接捕获载流子形成激子发光。在激基复合物3DTAPBP/TPBi体系中,主体3DTAPBP/TPBi的发光涵盖了客体C545T的激发光谱,光谱重叠面积大,且器件的电流密度-电压曲线几乎不随C545T厚度(浓度)的增加而变化,因此发光机制主要是来自3DTAPBP/TPBi与C545T之间的能量传递。而在非激基复合物CBP/TPBi体系中,主体CBP/TPBi的发光与客体C545T的激发光谱重叠面积相对较小,能量传递较弱,同时器件的电流密度-电压曲线随C545T厚度(浓度)的增加向高电压方向移动,说明C545T捕获载流子复合发光,使得C545T越厚驱动电压越高,因此非激基复合物体系中, C545T发光机制以直接捕获载流子为主。
The emissive mechanism of conventional fluorescent material coumarin C545 T was studied at the 3 DTAPBP/TPBi-based exciplex interface and CBP/TPBi-based non-exciplex interface. 3 DTAPBP is short for 2,2’-Bis(3-(N, N-di-p-tolylamino) phenyl) biphenyl, CBP for 4,4-bis(N-carbazolyl)-2,2-biphenyl and TPBi for 1,3,5-tris(1-phenyl-1 H-benzimidazol-2-yl) benzene. The device structures were ITO/MoO3/3 DTAPBP/C545 T/TPBi/LiF/Al and ITO/MoO3/CBP/C545 T/TPBi/LiF/Al, respectively. The photo-luminescence(PL) spectra of 3 DTAPBP, CBP and TPBi films are peaked at 415, 411 and 380 nm, respectively. The PL of 3 DTAPBP/TPBi heterojunction is centered at 412 and 490 nm. The peak of 412 nm is originated from 3 DTAPBP. Nevertheless, the peak at 490 nm neither belongs to the emission of 3 DTAPBP nor TPBi, which should be from the emission of exciplex at the 3 DTAPBP/TPBi interface. There is no additional peak for PL of the CBP/TPBi heterojunction film, which is the superposition of PL of CBP and TPBi films. That is, exciplex cannot be formed at the CBP/TPBi interface. The electroluminescent(EL) emission of C545 T is dominant for the ITO/MoO3/3 DTAPBP/C545 T/TPBi/LiF/Al and ITO/MoO3/CBP/C545 T/TPBi/LiF/Al devices. In both types of devices, C545 T can be diffused into 3 DTAPBP and TPBi or CBP and TPBi layers. For a doping system, the emissive mechanism of guest material could be divided into two possibilities: one is energy transfer between the host and the guest, and the other is direct charge trapping of the guest. In the exciplex system of 3 DTAPBP/TPBi, the F9 rster energy transfer from the host(3 DTAPBP/TPBi) to guest(C545 T) is predominant since there is a large overlap between the emission spectra of 3 DTAPBP/TPBi and excitation spectrum of C545 T. Consequently, the curves of current density vs. voltage(J-V) have been little or no influence by C545 T thickness(concentration). In the non-exciplex system of CBP/TPBi, direct charge trapping is the main emission mechanism due to the small overlap between photoluminescence of CBP/TPBi and C545 T excitation. The J-V characteristics show a reduction trend with the increase of C545 T thickness for operating voltage could be increased with the thickness of C545 T induced by the recombination of C545 T via direct charge carrier capture.