Fabrication and the Interlayer Coupling Effect of Twisted Stacked Black Phosphorus for Optical Applications

With a new polycarbonate-film-based dry transfer method, we successfully fabricated twisted stacked black phosphorus. Optical characterization showed the overlapping area had special optical response, and high-frequency Raman spectroscopy showed unexpected blue shifts in A(g)(1) and A(g)(2) modes. Density functional theory (DFT) calculations confirmed these blue shifts in twisted bilayer black phosphorus, and revealed significant interlayer coupling effects. Charge distribution calculations indicated other interactions beyond van der Waals force may exist in twisted bilayer black phosphorus. This finding may cast some insight on phonon modulation effect and give some potential applications such as optical filters and infrared photodetectors.