标题： 超快光电流检测表明，器件效率主要由超快激子解离而非激子扩散主导 显示英文标题

标题： Ultrafast photocurrent detection reveals that device efficiency is dominated by ultrafast exciton dissociation not exciton diffusion

摘要： 激子扩散到电荷分离界面是将能量转化为下一代光伏器件中电流的必要步骤。 在本报告中，得益于一种新的超快光谱仪设计，我们比较了使用光吸收和光电流检测的瞬态及二维光谱技术测量的激子动力学。 对于以半导体碳纳米管作为激子传输材料的器件，我们发现光吸收检测大大高估了长寿命激子对器件性能的重要性。 激子在纳米管之间扩散和转移数皮秒，但大部分光电流是在30飞秒内由扩散到C60电子转移材料的激子产生的。 这些结果改变了我们对这些光伏器件中最重要材料特性的理解。 光吸收检测测量所有激子，但并非所有光生激子都会产生电流。 为了理解器件效率，这项研究指出了直接测量产生光电流的激子动力学的必要性。 显示英文摘要

摘要： Excitons diffusing to a charge-separating interface is a necessary step to convert energy into current in next-generation photovoltaics. In this report, made possible by a new ultrafast spectrometer design, we compare exciton dynamics measured using both photoabsorption- and photocurrent-detected transient and 2D spectroscopies. For a device with semiconducting carbon nanotubes as the exciton transport material, we find that photoabsorption detection greatly overestimates the importance of long-lived excitons for device performance. Excitons diffuse and transfer between nanotubes for several picoseconds, but the large majority of photocurrent is created within 30fs by excitons that diffuse little to the C60 electron transfer material. These results change our understanding of the material features most important for these photovoltaics. Photoabsorption detection measures all excitons, but not all photogenerated excitons generate current. To understand device efficiency, this study points to the necessity for directly measuring the exciton dynamics responsible for photocurrent.