Photogeneration and decay of charge carriers in hybrid bulk heterojunctions of ZnO nanoparticles and conjugated polymers
Photogeneration and decay of charge carriers in hybrid bulk heterojunctions of ZnO nanoparticles and conjugated polymers
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DOI：
10.1021/jp055492m
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发表时间：
2006-06-01
影响因子：
3.3
通讯作者：
Siebbeles, Laurens D. A.
中科院分区：
文献类型：
--
作者：
Quist, Pieter A. C.;Beek, Waldo J. E.;Siebbeles, Laurens D. A.
采用微波光电导法研究了ZnO纳米粒子（直径5 nm）与聚[2-甲氧基-5-（3 '，7'-二甲基辛氧基）-1，4-亚苯基亚乙烯基]（MDMO-PPV）或聚（3-己基噻吩）（P3 HT）共混膜中载流子的光生和衰减。在可见光谱中的聚合物的激发被发现导致瞬态光电导由于激子在ZnO和共轭聚合物之间的界面处的解离。从类似的衰减动力学的光电导和紫外光照射的影响，可以得出结论，所测量的光电导是由于电子在ZnO。随着ZnO含量的增加，薄膜的光电导增加。这是由于增强形成的移动的电子的界面处的ZnO纳米粒子的簇，而不是在单个纳米粒子的激子解离。发现ZnO：MDMO-PPV和ZnO：P3 HT共混物的光电导对ZnO重量分数的依赖性是不同的。这很可能是由于ZnO：P3 HT共混物中存在较少数量的相对较大的ZnO簇和较短的激子扩散长度，与ZnO：MDMO-PPV共混物相比。曝光后的共混物膜的紫外光，光电导的幅度和寿命的显着增加被观察到。这是解释在ZnO中的电子陷阱的紫外线曝光的填充。
The photogeneration and decay of charge carriers in blend films of ZnO nanoparticles ( diameter 5 nm) and poly[2-methoxy-5-(3', 7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) or poly(3-hexylthiophene) (P3HT) were studied by means of microwave-photoconductance measurements. Excitation of the polymer in the visible spectrum was found to lead to a transient photoconductance due to dissociation of excitons at the interface between ZnO and the conjugated polymer. From the similar decay kinetics of the photoconductance and the effects of UV illumination, it is concluded that the measured photoconductance is due to electrons in ZnO. Increasing the weight fraction of ZnO in the blend films leads to a higher photoconductance. This is attributed to enhanced formation of mobile electrons by interfacial dissociation of excitons at clusters of ZnO nanoparticles rather than at individual nanoparticles. The dependence of the photoconductance on the weight fraction of ZnO is found to be different for ZnO: MDMO-PPV and ZnO: P3HT blends. This is most likely due to the presence of a smaller number of relatively large ZnO clusters in ZnO: P3HT blends and a shorter exciton diffusion length, as compared with ZnO: MDMO-PPV blends. After exposure of the blend films to UV light, a significant increase in the magnitude and the lifetime of the photoconductance is observed. This is explained in terms of the filling of electron traps in ZnO by UV exposure.