In the newly published work in Nano Letters, the team led by Cong Wang utilized a non-destructive, straight-forward optical technique—polarized transient absorption microscopy—which is not affected by sample size or uniformity. This technique was employed to measure the anisotropic mobility characteristics of violet phosphorus (VP) single crystals. The study revealed the anisotropic transport behavior of two-dimensional VP single crystals, clarified the intrinsic mechanism of anisotropic carrier transport in VP, and verified that the ambipolar mobility of VP single crystals along the a-axis can reach approximately 2100 cm²/(V·s), while the mobility along the b-axis is about 380 cm²/(V·s). The anisotropic ratio of carrier diffusion between the a-axis and b-axis can reach 5.5:1, which is consistent with the theoretical value. Steady-state optical techniques further demonstrated that the anisotropy of the deformation potential plays a crucial role in this behavior. These findings highlight the unique property of VP—high carrier mobility with strong anisotropy—and provide a theoretical basis for the design of angle-sensitive optoelectronic devices.

Figure 1. Two-dimensional violet phosphorus crystals show extremely high carrier mobility and significant anisotropy

Yuanyuan Zheng, a 2025 master’s graduate of Beijing University of Chemical Technology (BUCT), and  Cong Wang are the co-first authors of the article. Cong Wang, Xinfeng Liu and Shuai Yue from National Center for Nanoscience and Technology (NCNST) serve as the co-corresponding authors. BUCT is the first corresponding institution. This paper was supported by funding programs including the National Natural Science Foundation of China and the Fundamental Research Funds for the Central Universities.

Paper link: https://doi.org/10.1021/acs.nanolett.5c03034

Introduction of the Corresponding Author:

Cong Wang: Associate Professor at the College of Mathematics and Physics, Beijing University of Chemical Technology. Over the past five years, he has published 36 papers as a co-first author or co-corresponding author, which have been featured in journals such as Physical Review Letters, National Science Review, Nature Communications, Matter, Advanced Materials, Nano Letters, and Applied Physics Letters. He also holds the position of young editorial board member for 7 domestic and international journals, including Chip and Frontiers of Physics.