Interlayer charge transfer induced robust spin-valley polarization in hBN/TMDC/PbI₂ heterostructures in type I and type II configurations

Achieving a high degree of spin-valley polarization is the key task for emerging quantum technology. In most cases, generation and manipulation of spin-valley polarization with a significant value have been recorded with a cryogenic temperature regime. Here we demonstrate the mechanism of having a high degree of spin-polarization at the room temperature regime by manipulation of charge transfer and reduction of carrier lifetime. We have observed spin-valley polarization 70% in PbI₂ structure at RT limit. This intrinsic high spin polarization is due to high spin-orbit coupling in PbI₂ layers. However, we are able to manipulate spin-valley polarization in the range of 50%-80% with the hBN/TMDC/PbI₂ vdW heterostructure, at resonant excitation. With type I (MoS₂/PbI₂) band alignment, spin-valley polarization could be reached 80% by enhancing the PL emission. Whereas, with type II (WS₂/PbI₂) band alignment, it decreases to 50% with PL quenching. Helicity-resolved PL measurements (with CPexcitation) were performed to quantify the amount of spin-valley polarization. However, the effect of thickness, temperature, and excitation wavelength dependency has also been verified expensively. Here, polarized interlayer charge transfer could be the essential mechanism for high value of spin-polarization. Here the carrier lifetime is significantly lower in HS, whereas the spin relaxation lifetime is higher and this gives rise to having a high value of spin-polarization in the TMDC/PbI₂ HS system.