The physical proximity of layered materials in their van der Waals heterostructures (vdWhs) aids interfacial phenomena such as charge transfer (CT) and energy transfer (ET). Besides providing fundamental insights, CT and ET also offer routes to engineer optoelectronic properties of vdWhs. For example, harnessing ET in vdWhs can help to overcome the limitations of optical absorption imposed by the ultra-thin nature of layered materials and thus provide an opportunity for in situ enhancement of quantum efficiency for light-harvesting and sensing applications. While several spectroscopic studies on vdWhs probed the dynamics of CT and ET, the possible contribution of ET in the photocurrent generation remains largely unexplored. In this work, we investigate the role of nonradiative energy transfer (NRET) in the photocurrent through a vertical vdWh of SnSe₂/MoS₂/TaSe₂. We observe an unusual negative differential photoconductance (NDPC) arising from the existence of NRET across the SnSe₂/MoS₂ junction. Modulation of the NRET-driven NDPC characteristics with optical power results in a striking transition of the photocurrent’s power law from a sublinear to a superlinear regime. Our observations reveal the nontrivial influence of ET on the photoresponse of vdWhs, which offer insights to harness ET in synergy with CT for vdWh based next-generation optoelectronics.

中文翻译：

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负微分光电导作为范德华异质结中非辐射能量转移的特征

层状材料在其范德华异质结构 (vdWhs) 中的物理接近性有助于界面现象，例如电荷转移 (CT) 和能量转移 (ET)。除了提供基本的见解，CT 和 ET 还提供了设计 vdWhs 光电特性的途径。例如，在 vdWhs 中利用 ET 可以帮助克服由层状材料的超薄性质强加的光吸收限制，从而为原位提高光收集和传感应用的量子效率。虽然对 vdWhs 的几项光谱研究探索了 CT 和 ET 的动力学，但 ET 在光电流产生中的可能贡献仍然很大程度上未被探索。在这项工作中，我们研究了非辐射能量转移 (NRET) 在通过 SnSe ₂ /MoS ₂ /TaSe ₂的垂直 vdWh 的光电流中的作用。我们观察到由于 SnSe ₂ /MoS _{2 上}存在 NRET 引起的异常负差分光电导 (NDPC)交界处。用光功率调制 NRET 驱动的 NDPC 特性导致光电流的幂律从次线性到超线性状态的显着转变。我们的观察揭示了 ET 对 vdWhs 光响应的重要影响，这为利用 ET 与 CT 协同用于基于 vdWh 的下一代光电子学提供了见解。