On the Dissociation Efficiency of Charge Transfer Excitons and Frenkel Excitons in Organic Solar Cells: A Luminescence Quenching Study

被引:125
作者
Tvingstedt, Kristofer [1 ]
Vandewal, Koen [1 ]
Zhang, Fengling [1 ]
Inganas, Olle [1 ]
机构
[1] Linkoping Univ, COE, Dept Phys Chem & Biol, S-58183 Linkoping, Sweden
基金
瑞典研究理事会;
关键词
HYDROGENATED AMORPHOUS-SILICON; FIELD-ASSISTED DISSOCIATION; OPEN-CIRCUIT VOLTAGE; CONJUGATED POLYMERS; LIGHT-INTENSITY; TRANSFER STATES; PHOTOLUMINESCENCE; RECOMBINATION; PHOTOCURRENT; BLENDS;
D O I
10.1021/jp107587h
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
The field dependence of photocurrent found in many organic solar cells is a significant and detrimental setback for internal quantum efficiency. In this work we study the important contribution to this field dependence due to the dissociation efficiency of the weakly bound interfacial charge transfer (CT) state, crucial for organic bulk heterojunction solar cells. Three different donor polymers and two different acceptors are examined, and their respective dissociation characteristics are evaluated by photoluminescence (PL) quenching, both for Frenkel excitons and for the intermolecular charge transfer excitons. We observe that while the field-dependent photocurrent for pure polymers does correlate well with quenching efficiency, the CT exciton quenching from the blend generally displays a less pronounced correlation with extracted photocurrent. We further note that while the electroluminescence and photoluminescence of the pure polymer are identical, we observe a red shift for the blend electroluminescence. This indicates that lower energetic states, not visible in PL, are available in the blend. The emissive state of the blends probed by PL is therefore proposed to originate from sites that are involved in photocurrent generation to a lesser extent.
引用
收藏
页码:21824 / 21832
页数:9
相关论文
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