Abnormal linear dichroism transition in two-dimensional PdPS
Gang Li, Zheng Chen, Hanlin Zhang, Mengxi Yu, Hui Zhang, Jiawnag Chen, Zihan Wang, Shiqi Yin, Weichang Lin, Peng-Lai Gong, Longhui Zeng, Xiangde Zhu, Wensen Wei, Mingliang Tian, Liang Li
Abstract
The linear dichroism (LD) conversion shows promising applications for polarized detectors, optical transition and light propagation. However, polarity reversal always occurs at a certain wavelength in LD materials, which can only distinguish two wavelength bands as wavelength-selective photodetectors. In this study, the multi-degree-of-freedom of optical anisotropy based on 2D PdPS flakes is carefully described, in which four critical switching wavelengths are observed. Remarkably, the quadruple LD conversion shows a significant wavelength-dependent behavior, allowing us to pinpoint five wavelength bands, 200-239 nm, 239-259 nm, 259-469 nm, 469-546 nm, and 546-700 nm, for a wavelength-selective approach to photodetectors. In addition, the polarized photoresponse under 532 nm was realized with an anisotropy factor of ∼1.51 and further illustrated the in-plane anisotropy. Raman spectroscopy of PdPS flakes also shows strong phonon anisotropy. The unique wavelength-selective property shows great potential for the miniaturization and integration of photodetectors.