Coulomb Barrier for Charge Separation at an Organic Semiconductor Interface

被引：152

作者：

Muntwiler, Matthias ^{[1
]}

Yang, Qingxin ^{[1
]}

Tisdale, William A. ^{[1
]}

Zhu, X. -Y. ^{[1
]}

机构：

[1] Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA

来源：

PHYSICAL REVIEW LETTERS | 2008年 / 101卷 / 19期

基金：

美国国家科学基金会;

关键词：

D O I：

10.1103/PhysRevLett.101.196403

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

Charge transfer (CT) excitons across donor-acceptor interfaces are believed to be barriers to charge separation in organic solar cells, but little is known about their physical characteristics. Here, we probe CT excitons on a crystalline pentacene surface using time-resolved two-photon photoemission spectroscopy. CT excitons of 1s, 2s, and 3s characters are bound by Coulomb energies of 0.43, 0.21, 0.12 eV, respectively, in agreement with quantum mechanical modeling. The large binding energy of the 1s CT exciton excludes its participation in photovoltaics. Efficient charge separation in organic heterojunction solar cells must involve a series of hot CT excitons.

引用

页数：4

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