Ultrafast Terahertz Photoconductivity of Photovoltaic Polymer-Fullerene Blends: A Comparative Study Correlated with Photovoltaic Device Performance

被引：54

作者：

Jin, Zuanming ^{[1
]}

Gehrig, Dominik ^{[1
]}

Dyer-Smith, Clare ^{[1
]}

Heilweil, Edwin J. ^{[2
]}

Laquai, Frederic ^{[1
]}

Bonn, Mischa ^{[1
]}

Turchinovich, Dmitry ^{[1
]}

机构：

[1] Max Planck Inst Polymer Res, D-55128 Mainz, Germany

[2] NIST, Gaithersburg, MD 20899 USA

来源：

JOURNAL OF PHYSICAL CHEMISTRY LETTERS | 2014年 / 5卷 / 21期

关键词：

SOLAR-CELLS; CARRIER DYNAMICS; QUANTUM EFFICIENCY; SPECTROSCOPY; MOBILITIES; GENERATION; COPOLYMER;

D O I：

10.1021/jz501890n

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：

Ultrafast photoinduced carrier dynamics in prototypical low band gap polymer:fullerene photovoltaic blend films PTB7:PC70BM and P3HT:Pe(70)BM is investigated using ultrafast terahertz (THz) spectroscopy. The subpicosecond and fewpicosecond decays of THz-probed photoconductivities for both compounds are observed, attributed to the rapid formation of polaron pairs by exciton-exciton annihilation and subsequent polaron pair annihilation, respectively. The transient THz photoconductivity spectra of PTB7:PC70BM are well described by the Drude-Smith (DS) model, directly yielding the important charge transport parameters such as charge carrier density, momentum scattering time, and effective localization. By comparison with P3HT:PC70BM, we find that in PTB7:PC70BM the mobile charge carrier photoconductivity is significantly enhanced by a factor of 1.8 and prevails for longer times after charge formation, due to both improved mobile charge carrier yield and lower charge localization. In PTB7:PC70BM, a strong dependency of electron momentum scattering time on electron density was found, well parametrized by the empirical Caughey-Thomas model. The difference in ultrafast photoconductivities of both P3HT:PC70BM and PTB7:PC70BM is found to correlate very well with the performance of photovoltaic devices based on those materials.

引用

页码：3662 / 3668

页数：7

共 40 条

[1] Photoinduced charge carrier generation in a poly(3-hexylthiophene) and methanofullerene bulk heterojunction investigated by time-resolved terahertz spectroscopy [J].