近日，中国地质大学（武汉）杜桃园团队报道了扭曲过渡金属二硫族化合物异质层中的低阈值层间激子倍增。相关论文于2026年2月10日发表在《光：科学与应用》杂志上。

单光子吸收引发的多激子生成效应可显著提升发光与能量转换中的量子效率。然而，其实际应用受限于高光子能量阈值、材料大带隙及激子快速复合等瓶颈。

研究组报道了扭转范德瓦耳斯异质双层中间层激子倍增效应的观测，该过程阈值低至II型带隙的两倍，且产生的多个层间激子展现出纳秒级寿命。这些特性直接回应了MEG的核心挑战，促使层间激子发光与光电流量子效率显著提升。理论计算证实了实验结果，揭示低阈值IXM由层间热载流子散射驱动，并伴随吸引性IX相互作用——即使在动量失配显著的大扭转角下亦然。由于强热载流子层间转移与高效谷间碰撞电离，扭转角诱导的动量失配对IXM阈值影响甚微。

在小扭转角异质双层中IXM效率可达~90%，但随角度增大及泵浦光子能量升高而下降，该趋势归因于层间热载流子库仑散射的减弱。进一步，研究组演示了IXM驱动的光电流倍增效应。外加电场可进一步降低IXM阈值并提高IX产额，使自供电异质双层光电二极管的量子效率提升两倍、响应度提升四倍。该工作确立了IXM作为高效载流子倍增光电子学的前沿机制，并为稳定多激子的多体物理提供了深刻见解。

附：英文原文

Title: Low-threshold interlayer exciton multiplication in twisted transition metal dichalcogenides heterobilayers

Author: Wang, Pengzhi, Wang, Gan, Wang, Chenhao, Wei, Qi, Chen, Yuxuan, Liu, Qi, Zhou, Luwei, Ren, Hui, Zhang, Xiang, Peng, Jiangbo, Zhao, Leyi, Du, Tao-Yuan, Li, Mingjie

Issue&Volume: 2026-02-10

Abstract: Multiple exciton generation (MEG) from single-photon absorption can enhance quantum efficiencies in light emission and energy conversion. However, its practical application is limited by high photon-energy thresholds, large material bandgaps, and rapid exciton recombination. Here, we report the observation of interlayer exciton multiplication (IXM) in twisted van der Waals heterobilayers, where the process threshold is as low as twice the type-II bandgap and the resulting multiple interlayer excitons (IXs) exhibit nanosecond-scale lifetimes. These properties directly address the core challenges of MEG, leading to a significant boost in both interlayer exciton emission and photocurrent quantum efficiency. Theoretical calculations confirm the experimental results, revealing that low-threshold IXM is facilitated by interlayer hot-carrier scattering and is accompanied by attractive IX interactions, even at larger twist angles where momentum mismatch is significant. Twist-angle-induced momentum mismatches have a minimal impact on the IXM threshold due to strong hot-carrier interlayer transfer and efficient intervalley impact ionization. The IXM efficiency reaches ~90% in small-twist-angle heterobilayers but decreases at larger angles and higher pump photon energies, a trend attributed to reduced interlayer hot-carrier Coulomb scattering. Furthermore, we demonstrate photocurrent multiplication driven by IXM. Applied electric fields further lower the IXM threshold and increase the IX yield, enabling a twofold enhancement in quantum efficiency and a fourfold increase in responsivity in a self-powered heterobilayer photodiode. Our results establish IXM as a promising mechanism for high-efficiency carrier-multiplication optoelectronics and provide insights into the many-body physics of stable multiple excitons.

DOI: 10.1038/s41377-026-02193-w

Source: https://www.nature.com/articles/s41377-026-02193-w