Trion photoluminescence and trion stability in atomically thin semiconductors

Abstract

The optical response of doped monolayer semiconductors is governed by trions, i.e. photoexcited electron-hole pairs bound to doping charges. While their photoluminescence (PL) signatures have been identified in experiments, a microscopic model consistently capturing bright and dark trion peaks is still lacking. In this work, we derive a generalized trion PL formula on a quantum-mechanical footing, considering direct and phonon-assisted recombination mechanisms. We show the trion energy landscape in WSe${}_2$ by solving the trion Schrödinger equation. We reveal that the mass imbalance between equal charges results in less stable trions exhibiting a small binding energy and, interestingly, a large energetic offset from exciton peaks in PL spectra. Furthermore, we compute the temperature-dependent PL spectra for n- and p-doped monolayers and predict yet unobserved signatures originating from trions with an electron at the $\Lambda$ point. Our work presents an important step towards a microscopic understanding of the internal structure of trions determining their stability and optical fingerprint.

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Cited by in corpus (4)

• Probing excitons with time-resolved momentum microscopy
• Electrically tunable layer-hybridized trions in doped WSe${}_2$ bilayers
• Impact of an electron Wigner crystal on exciton propagation
• Brightening dark excitons and trions in systems with a Mexican-hat energy dispersion: example of InSe