We suggest a phenomenological theory of the polarization conversions effect, an excitonic analog of the first-order spatial dispersion phenomena which is, however, observed in the photoluminescence rather than in the passing light. The optical polarization response of a model system of electrically neutral quantum dots subject to the magnetic field along the growth axis was calculated by means of the pseudospin method. All possible forms of the polarization response are determined by nine different field-dependent coefficients which represent, therefore, a natural basis for classification of a variety of conversions. Existing experimental data can be well inscribed in this classification scheme. Predictions were made regarding two effects which have not been addressed experimentally.
Cataloguing MoSi$_2$N$_4$ and WSi$_2$N$_4$ van der Waals Heterostructures: An Exceptional Material Platform for Excitonic Solar Cell Applications
二维（2D）材料范德华异质结构（vdWHs）提供了一条革命性的路线，以实现超越传统硅基PN结太阳能电池的高性能太阳能转换器件。尽管近年来取得了巨大的研究进展，但具有优异激子太阳能电池转换效率和光学性质的vdWHs的搜索仍然是一个开放的理论和实验探索。在这里，我们表明，由MoSi $_2$ N $_4$和WSi $_2$ N $_4$单层组成的vdWH家族为开发高性能的双激子太阳能电池和光子器件提供了一个引人注目的材料平台。利用第一性原理计算，我们构造并分类了51种MoSi $_2$ N $_4$和WSi $_2$ N $_4$基[（Mo，W）Si $_2$ N $_4$ ] vdWH，它们由各种金属、半金属、半导体、绝缘和拓扑二维材料组成.有趣的是，MoSi $_2$ N $_4$ /（InSe，WSe $_2$）被鉴定为II型vdWH，其具有达到远超过20%的优异的激子太阳能电池功率转换效率，这与现有技术的硅太阳能电池竞争。（Mo，W）Si $_2$ N $_4$ vdWH系列在可见光和紫外光区都表现出很强的光吸收。在（Mo，W）Si $_2$ N $_4$/ $α_2$ -（Mo，W）Ge $_2$ P $_4$ vdWHs中可以实现超过40%的超大峰值紫外吸收，接近自支撑2D材料的最大吸收极限。我们的发现揭示了（Mo，W）Si $_2$ N $_4$ vdWH在设计最终紧凑的…
Plasmon exciton coupling enhances second order nonlinear response in borophene ZnO hybrid structures
Institute of Experimental and Applied Physics, Kiel University（基尔大学实验与应用物理研究所）；Department of Physics, University of Tehran（德黑兰大学物理系）；Kiel Nano, Surface, and Interface Science KiNSIS, Kiel University（基尔大学基尔纳米、表面与界面科学(KiNSIS)）
Many-Body effects beyond excitons in second-harmonic generation of monolayer MoS$_{2}$
University of the Basque Country UPV/EHU（巴斯克大学）；Centro de Física de Materiales, Universidad del País Vasco UPV/EHU（巴斯克大学材料物理中心）；Ikerbasque Foundation（伊卡巴斯基基金会）；Donostia International Physics Center（圣塞巴斯蒂安国际物理中心）
Exciton enhanced nonlinear optical responses in monolayer h-BN and MoS2: Insight from first-principles exciton-state coupling formalism and calculations
University of California at Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；National Center of Theoretical Physics（国家理论物理中心）；Institute of Atomic and Molecular Sciences, Academia Sinica（中央研究院原子与分子科学研究所）
