Optical cooling by interfacial charge transfer in 2D heterostructures.
basic_science · Level V
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- Record sourced from PubMed, PMID 42343122.
- Also identified by DOI 10.1038/s41586-026-10662-w.
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Abstract
Optical refrigeration, or laser cooling of solids<sup>1</sup>, offers a cryogen-free route to temperature control for quantum and electronic systems. Existing progress<sup>2-8</sup> relies on a phonon-assisted up-conversion photoluminescence approach, which remains constrained by stringent material and excitation requirements. Here we demonstrate a distinct route, interfacial-charge-transfer-driven optical cooling, in two-dimensional semiconductor heterostructures. Photo-excited carriers in WSe<sub>2</sub> cross a type-II junction into MoSe<sub>2</sub> or WS<sub>2</sub>, extracting lattice energy nonradiatively-through a phonon-assisted interfacial charge transfer process. Raman and photoluminescence measurements show prominent low-temperature signatures in the WSe<sub>2</sub> layer, with transient absorption spectroscopy identifying a phonon-assisted, barrier-activated interlayer charge transfer. Molecular dynamics simulations show a prominent interfacial thermal resistance sustaining the temperature gradient. This barrier-mediated phonon extraction bypasses the need for near-unity quantum efficiency or resonant excitation, offering a promising strategy for cryogen-free refrigeration and thermal management in quantum, optoelectronic and nanoscale systems.