Photoinduced Charge-Carrier Generation in Epitaxial MOF Thin Films: High Efficiency as a Result of an Indirect Electronic Band Gap?
Photoinduced Charge-Carrier Generation in Epitaxial MOF Thin Films: High Efficiency as a Result of an Indirect Electronic Band Gap?
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DOI：
10.1002/anie.201501862
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发表时间：
2015-06-15
影响因子：
16.6
通讯作者：
Woell, Christof
中科院分区：
文献类型：
--
作者：
Liu, Jinxuan;Zhou, Wencai;Woell, Christof
对于无机半导体，晶序导致能带结构，从而导致与无序材料的巨大差异。一个例子是间接带隙的存在。对于有机半导体，通常不考虑这种效应，因为能带通常是平坦的，因此带隙是直接的。在这里，我们展示了电子结构计算的结果，证明卟啉的有序阵列揭示了占据和未占据带的小分散性，导致形成小的间接带隙。我们在此证明，这种有序结构可以通过液相外延来制造，并且相应的晶体有机半导体表现出优异的光物理性质，包括大的载流子迁移率和异常大的载流子生成效率。我们基于这种新型材料制造了原型有机光伏器件，表现出卓越的效率。
For inorganic semiconductors crystalline order leads to a band structure which gives rise to drastic differences to the disordered material. An example is the presence of an indirect band gap. For organic semiconductors such effects are typically not considered, since the bands are normally flat, and the band-gap therefore is direct. Herein we show results from electronic structure calculations demonstrating that ordered arrays of porphyrins reveal a small dispersion of occupied and unoccupied bands leading to the formation of a small indirect band gap. We demonstrate herein that such ordered structures can be fabricated by liquid-phase epitaxy and that the corresponding crystalline organic semiconductors exhibit superior photophysical properties, including large charge-carrier mobility and an unusually large charge-carrier generation efficiency. We have fabricated a prototype organic photovoltaic device based on this novel material exhibiting a remarkable efficiency.