Organic photovoltaic cells are partiuclarly sensitive to exciton harvesting and are thus, a useful platform for the characterization of exciton diffusion. While device photocurrent spectroscopy can be used to extract the exciton diffusion length, this method is frequently limited by unknown interfacial recombination losses. We resolve this limitation and demonstrate a general, device-based photocurrent-ratio measurement to extract the intrinsic diffusion length. Since interfacial losses are not active layer specific, a ratio of the donor- and acceptor-material internal quantum efficiencies cancels this quantity. We further show that this measurement permits extraction of additional device-relevant information regarding exciton relaxation and charge separation processes. The generality of this method is demonstrated by measuring exciton transport for both luminescent and dark materials, as well as for small molecule and polymer active materials and semiconductor quantum dots. Thus, we demonstrate a broadly applicable device-based methodology to probe the intrinsic active material exciton diffusion length.

有机光伏电池对激子的收获特别敏感，因此是表征激子扩散的有用平台。虽然可以使用器件光电流光谱法来提取激子扩散长度，但该方法经常受到未知的界面重组损失的限制。我们解决了这一局限性，并演示了一种基于设备的常规光电流比测量方法来提取本征扩散长度。由于界面损耗不是特定于活性层的，因此供体和受体材料内部量子效率之比抵消了该数量。我们进一步表明，该测量允许提取有关激子弛豫和电荷分离过程的其他与设备有关的信息。通过测量发光和暗物质以及小分子和聚合物活性物质以及半导体量子点的激子传输，证明了该方法的普遍性。因此，我们展示了一种广泛适用的基于设备的方法，以探究内在活性材料的激子扩散长度。