Axially‐Polarized Excitonic Series and Anisotropic van der Waals Stacked Heterojunction in a Quasi‐1D Layered Transition‐Metal Trichalcogenide

Anisotropic optical 2D materials are crucial for achieving multiple-quanta functions within quantum materials, which enables the fabrication of axially polarized electronic and optoelectronic devices. In this work, multiple excitonic emissions owning polarization-sensitive orientations are clearly detected in a multilayered quasi-1D ZrS₃ nanoribbon with respect to the nanostripe edge. Four excitons denoted as A_S1, A_S2, A_S, and A₂ with E ⊥ b polarized direction and one prominent A₁ exciton with E || b polarized emission are simultaneously detected in the polarized micro-photoluminescence (µPL) measurement of 1.9-2.2 eV at 10 K. In contrast to light emission, polarized micro-thermoreflectance (µTR) measurements are performed to identify the polarization dependence and verify the excitons in the multilayered ZrS₃ nanoribbon from the perspective of light absorption. At 10 K, a prominent and broadened peak on the lower-energy side, containing an indirect resonant emission (D_I) observed by µPL and an indirect defect-bound exciton peak (A_Ind) observed by both µPL and µTR, is simultaneously detected, confirming the existence of a quasi-direct band edge in ZrS₃. A van der Waals stacked p-GaSe/n-ZrS₃ heterojunction solar cell is fabricated, which demonstrates a maximum axially-polarized conversion efficiency up to 0.412% as the E || b polarized light incident onto the device.