Broad photoluminescence of black phosphorus with electrochemical intercalation of organic ions

Black phosphorus is a highly interesting two-dimensional material with a tunable band gap, ultra-high carrier mobility, and excellent optoelectronic properties. Its van der Waals spacing creates conditions for the entry of foreign substances, and various properties of BP can be effectively regulated by intercalation. In this paper, organic ammonium salts (CTAB, hexadecyl trimethyl ammonium bromide and TBAB, Tetrabutyl ammonium bromide) were chosen as the intercalated guests and BP bulk crystals were used as the intercalation hosts, and the effects of intercalation on the Raman as well as photoluminescence (PL) properties of BP were mainly investigated. The results show that the intercalation of organic ions leads to an overall redshift of the Raman modes corresponding to the three phonon vibrational modes of A_g¹, B_2g and A_g². In particular, the PL emission spectrum of the intercalated BP bulk exhibits a continuous spectrum bridging the peaks of the bilayer (1.35 eV), monolayer (1.7 eV) and the defect states. The prepared intercalation products also possess good stability under atmospheric conditions. Our study provides an idea for modulating the electronic and optical properties of bulk 2D materials, which has potential applications in the field of optoelectronics of crystalline materials.