Duty-cycle dependence of photo-induced displacement current in MISIM photocells
Duty-cycle dependence of photo-induced displacement current in MISIM photocells
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DOI：
10.1016/j.orgel.2022.106632
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发表时间：
2022-08
影响因子：
3.2
通讯作者：
Akihiro Tomimatsu;S. Yokokura;K. Awaga
中科院分区：
文献类型：
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作者：
Akihiro Tomimatsu;S. Yokokura;K. Awaga
有机光电转换具有低成本和可调谐光传感等多种优点，但有机半导体也存在明显的缺点，例如空气中的不稳定和载流子迁移率低。为了克服这些问题，我们最近提出了一种[金属（M）|绝缘体（I）|半导体（S）|绝缘体（I）|金属（M）]结构（MISIM光电池），该结构可以有效地感应光致位移电流，而无需任何载流子通过S|I和I|M界面。在目前的工作中，我们研究了 MISIM 光电池的占空比依赖性，以确定提高光电转换速度和效率以实现实际应用的指导原则。我们制作了一种由酞菁锌（ZnPc）和富勒烯（C60）双层作为S层、聚对二甲苯C（PC）作为I层组成的MISIM光电池，并测试了光电流对占空比D=tON/(tON+tOFF)的依赖性，其中tON和tOFF分别是光调制下一个周期的光照射和阻挡时间。通过在 0.2–2.0 μs 范围内独立改变 tON 和 tOFF，发现瞬态光电流的上升时间通过占空比改善了约 30%。我们还发现，一个周期内产生的载流子 Q 在 D≈0.4 处达到最大值，并且时间平均值随着调制频率的增加而逐渐增加。 MISIM 光电管的理论模型很好地解释了 Q 的这一特性。
Organic optoelectronic conversion possesses various advantages such as low cost and tunable light sensing, but organic semiconductors suffer from significant drawbacks, such as instability in air and low carrier mobility. To overcome them, we recently proposed a [metal (M)|insulator (I)|semiconductor (S)|insulator (I)|metal (M)] structure (MISIM photocells) that can effectively induce photo-induced displacement current without any passage of carriers through the S|I and I|M interfaces. In the present work, we investigated the duty-cycle dependence of MISIM photocells, to determine the guiding principles for improving the speed and efficiency of the optoelectronic conversion toward its practical application. We formed an MISIM photocell consisting of a bilayer of zinc phthalocyanine (ZnPc) and fullerene (C60) as the S layer and parylene C (PC) as the I layers, and tested the dependence of the photocurrent on the duty cycleD=tON/(tON+tOFF), wheretONandtOFFare the light illumination and blocking times, respectively, in one cycle under light modulation. By independently changingtONandtOFFin the range of 0.2–2.0 μs, the rise time of the transient photocurrent was found to be improved by approximately 30% by the duty cycle. We also revealed that the charge carriersQgenerated in one cycle reached their maximum atD≈ 0.4, and the time average increased gradually with an increase in modulation frequency. This feature ofQwas well explained by a theoretical model for the MISIM photocells.