Infrared Interlayer Excitons in Twist‐Free MoTe2/MoS2 Heterobilayers

Abstract Excitonic devices based on interlayer excitons in van der Waals heterobilayers are a promising platform for advancing photoelectric interconnection telecommunications. However, the absence of exciton emission in the crucial telecom C‐band has constrained their practical applications. Here, this limitation is addressed by reporting exciton emission at 0.8 eV (1550 nm) in a chemically vapor‐deposited, strictly aligned MoTe 2 /MoS 2 heterobilayer, resulting from the direct bandgap transitions of interlayer excitons as identified by momentum–space imaging of their electrons and holes. The decay mechanisms dominated by direct radiative recombination ensure constant emission quantum yields, a basic demand for efficient excitonic devices. The atomically sharp interface enables the resolution of two narrowly‐splitter transitions induced by spin–orbit coupling, further distinguished through the distinct Landé g‐factors as the fingerprint of spin configurations. By electrical control, the double transitions coupling into opposite circularly‐polarized photon modes, preserve or reverse the helicities of the incident light with a degree of polarization up to 90%. The Stark effect tuning extends the emission energy range by over 150 meV (270 nm), covering the telecom C‐band. The findings provide a material platform for studying the excitonic complexes and significantly boost the application prospects of excitonic devices in silicon photonics and all‐optical telecommunications.