Nakamura M, Horiuchi S, Kagawa F, Ogawa N, Kurumaji T, Tokura Y, Kawasaki M
RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan.
PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, 332-0012, Japan.
Nat Commun. 2017 Aug 17;8(1):281. doi: 10.1038/s41467-017-00250-y.
Shift current is a steady-state photocurrent generated in non-centrosymmetric single crystals and has been considered to be one of the major origins of the bulk photovoltaic effect. The mechanism of this effect is the transfer of photogenerated charges by the shift of the wave functions, and its amplitude is closely related to the polarization of the electronic origin. Here, we report the photovoltaic effect in an organic molecular crystal tetrathiafulvalene-p-chloranil with a large ferroelectric polarization mostly induced by the intermolecular charge transfer. We observe a fairly large zero-bias photocurrent with visible-light irradiation and switching of the current direction by the reversal of the polarization. Furthermore, we reveal that the travel distance of photocarriers exceeds 200 μm. These results unveil distinct features of the shift current and the potential application of ferroelectric organic molecular compounds for novel optoelectric devices.The bulk photovoltaics refers to an effect whereby electrons move directionally in non-centrosymmetric crystals upon light radiation. Here, Nakamura et al. observe this effect in a ferroelectric organic charge-transfer complex, which shows large diffusion distance of photogenerated electrons over 200 µm.
位移电流是在非中心对称单晶中产生的稳态光电流，被认为是体光伏效应的主要起源之一。这种效应的机制是光生电荷通过波函数的位移进行转移，其幅度与电子起源的极化密切相关。在此，我们报道了在一种有机分子晶体四硫富瓦烯-对氯苯醌中观察到的光伏效应，该晶体具有主要由分子间电荷转移诱导产生的大铁电极化。我们观察到在可见光照射下有相当大的零偏压光电流，并且电流方向会随着极化的反转而改变。此外，我们揭示了光载流子的传输距离超过200μm。这些结果揭示了位移电流的独特特征以及铁电有机分子化合物在新型光电器件中的潜在应用。体光伏是指一种效应，即电子在光辐射下在非中心对称晶体中定向移动。在此，中村等人在一种铁电有机电荷转移复合物中观察到了这种效应，该复合物显示光生电子的扩散距离超过200μm。
