Photocurrent transients in all-polymer solar cells: Trapping and detrapping effects

被引：146

作者：

McNeill, Christopher R. ^{[1
]}

Hwang, Inchan ^{[1
]}

Greenham, Neil C. ^{[1
]}

机构：

[1] Univ Cambridge, Dept Phys, Cavendish Lab, Cambridge CB3 0HE, England

来源：

JOURNAL OF APPLIED PHYSICS | 2009年 / 106卷 / 02期

基金：

英国工程与自然科学研究理事会;

关键词：

TRANSPORT;

D O I：

10.1063/1.3177337

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

We have studied photocurrent transients in all-polymer bulk-heterojunction solar cells based on poly(3-hexylthiophene) and poly ((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(3-hexylthien-5-yl)-2,1,3-benzothiadiazole]-2',2 ''-diyl). By illuminating devices with square pulses of light of varying intensity, we reveal nonlinear photocurrent transients on the timescale of tens of microseconds. These microsecond photocurrent transients are attributed to the effects of trapping and detrapping of charges on this timescale, in particular, electrons. The buildup of trapped electrons results in the appearance of a peak in the photocurrent at high intensities at similar to 10 mu s after turn on. This trapped charge produces a local reduction in the strength of the internal electric field near the anode resulting in a net decrease in charge separation efficiency and an increase in the likelihood of bimolecular recombination due to increased and overlapping electron and hole densities. After turn off, a long photocurrent tail is observed with charge still being extracted after 0.5 ms consistent with the detrapping of deeply trapped charges. We are able to reproduce the observed transient photocurrent features using a time-dependent drift-diffusion model incorporating the trapping and detrapping of electrons. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3177337]

引用

页数：8

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