Electronic structures of interfacial states formed at polymeric semiconductor heterojunctions

被引:175
作者
Huang, Ya-Shih [1 ,2 ]
Westenhoff, Sebastian [1 ]
Avilov, Igor [2 ]
Sreearunothai, Paiboon [1 ]
Hodgkiss, Justin M. [1 ]
Deleener, Caroline [2 ]
Friend, Richard H. [1 ]
Beljonne, David [2 ]
机构
[1] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England
[2] Univ Mons, Lab Chem Novel Mat, B-7000 Mons, Belgium
基金
英国工程与自然科学研究理事会;
关键词
D O I
10.1038/nmat2182
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Heterojunctions between organic semiconductors are central to the operation of light-emitting and photovoltaic diodes, providing respectively for electron-hole capture and separation. However, relatively little is known about the character of electronic excitations stable at the heterojunction. We have developed molecular models to study such interfacial excited electronic excitations that form at the heterojunction between model polymer donor and polymer acceptor systems: poly( 9,9-dioctylfluorene-co-bisN, N-(4-butylphenyl)-bis-N, N-phenyl-1,4-phenylenediamine) (PFB) with poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT), and poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) with F8BT. We find that for stable ground-state geometries the excited state has a strong charge-transfer character. Furthermore, when partly covalent, modelled radiative lifetimes ( similar to 10(-7) s) and off-chain axis polarization (30 degrees) match observed 'exciplex' emission. Additionally for the PFB: F8BT blend, geometries with fully ionic character are also found, thus accounting for the low electroluminescence effciency of this system.
引用
收藏
页码:483 / 489
页数:7
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