近日，英国牛津大学Laura M. Herz团队报道了赝直接半导体中的延迟电子–空穴复合。相关论文发表在2026年10月28日出版的《自然》杂志上。

基尔霍夫于1860年证明了黑体辐射中吸收率与发射率之间的互易关系，从而确立了一条普遍原理：良好的吸收体也必然是良好的发射体。该原理构成了广义普朗克定律的基础；当以范鲁斯布鲁克–肖克利方程的形式应用于半导体时，它会对太阳能转换造成显著限制。

研究组证明，在诸如硫化铋这类具有赝直接带隙特征的半导体中，可以规避这种互易关系——所谓赝直接带隙，即具有一个较低能量的间接跃迁，并伴随一个位于其上方约几个kBT处的直接跃迁。在确定硫化铋的赝直接带隙性质之后，研究组揭示了该特征如何相对于经典直接半导体显著延缓该材料中的双分子电子–空穴复合。由此形成的高吸收系数与延迟复合的结合，为克服与普朗克定律相关的限制提供了前所未有的可能，并在太阳能转换方面具有深远潜力。

附：英文原文

Title: Delayed electron–hole recombination in a pseudo-direct semiconductor

Author: Righetto, Marcello, Banerjee, Debalina, Jia, Zhenglin, Lilly, Joshua R. S., Lim, Vincent J. -Y., Lal, Snigdha, Yan, Siyu, Lee, Jae Eun, Patel, Jay B., Johnston, Michael B., Lin, Qianqian, Filip, Marina R., Herz, Laura M.

Issue&Volume: 2026-10-28

Abstract: Kirchhoff demonstrated the reciprocity between absorptivity and emissivity for blackbody radiation in 1860 (ref.1), thereby establishing the general principle that a good absorber must also be a good emitter. This principle underpins the generalized Planck’s law2 and, when applied to semiconductors—in the form of the van Roosbroeck–Shockley equation3—results in substantial limitations to solar energy conversion. Here we demonstrate how this reciprocity can be circumvented in semiconductors, such as bismuth sulfide, showing a pseudo-direct bandgap character—that is, featuring a lower-energy indirect transition paired with a direct transition placed a few kBT above. After determining the pseudo-direct bandgap nature of bismuth sulfide, we reveal how this feature substantially retards bimolecular electron–hole recombination in this material with respect to classic direct semiconductors4. The resulting combination of a high absorption coefficient and delayed recombination offers the unprecedented possibility of overcoming limitations associated with Planck’s law, with far-reaching potential for solar energy conversion.

DOI: 10.1038/s41586-026-11223-x

Source: https://www.nature.com/articles/s41586-026-11223-x