بلورة طبقية تتعلم التقاط الضوء سريع

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2603.24834

Paucity of naturally occurring noncentrosymmetric materials is stimulating growing interest in engineered two-dimensional systems for nonlinear optical applications. Here, we show that breaking inversion symmetry in centrosymmetric bilayer Bi$$_2$$Se$$_3$$ through twisting, point-defect insertion, or the application of an external electric field unlocks rich nonlinear optical responses. In twisted bilayer Bi$$_2$$Se$$_3$$ at the first commensurate angle of 21.78$$^\circ$$, we find peak shift and injection current conductivities of -14 $$ nm.\mu AV^{-2}$$ and 104 $$\times 10^8$$ $$nm.A V^{-2}s^{-1}$$, respectively, which lie in the visible spectrum and enable efficient THz applications. The external electric field and point-defect insertion both transform the bilayer into C$$_ {3v}$$ symmetry, with the selenium vacancy (V$$_{Se}$$) achieving peak shift and injection current conductivities of -190 nm.$$\mu AV^{-2}$$ and -170 $$\times 10^8$$ $$nm.A V^{-2}s^{-1}$$. In all three cases, the peak nonlinear optical responses are found to be comparable to those of benchmark 2D materials such as GeS, and the broadband responses, including helicity-dependent current generation, make these engineered bilayers viable candidates for next-generation 2D photovoltaics.