Fullerenes are electron transporting organic semiconductors with a wide range of applications. In particular, methanofullerenes have been the preferred choice for solution-processed solar cells and photodiodes. The wide applicability of fullerenes as both ‘n-type’ transport materials and electron acceptors is clear. However, what is still a matter of debate is whether the fullerenes can also support efficient transport of holes, particularly in diode geometries. In this letter, we utilize a number of recently developed experimental methods for selective electron and hole mobility measurements. We show for the two most widely used solution processable fullerenes, PC70- and-PC60BM, that whilst both exhibit electron mobilities as high as 10⁻³ cm²/Vs, their hole mobilities are < 10⁻⁹ cm²/Vs. Thus charge transport in these fullerenes can be considered predominantly unipolar in diode configurations.

富勒烯是具有广泛应用的电子传输有机半导体。特别地，对于溶液处理的太阳能电池和光电二极管，甲烷富勒烯已经成为优选的选择。富勒烯作为“ n型”传输材料和电子受体的广泛适用性是显而易见的。然而，仍然有争议的是，富勒烯是否也能支持空穴的有效传输，特别是在二极管的几何形状中。在这封信中，我们利用许多最新开发的实验方法进行选择性电子和空穴迁移率测量。对于两种最广泛使用的溶液可加工富勒烯，我们展示了PC70-和-PC60BM，它们都表现出高达10 ^-3  cm ^2的电子迁移率/ Vs，其空穴迁移率<10 ^-9  cm ² / Vs。因此，在二极管结构中，这些富勒烯中的电荷传输主要被认为是单极性的。