Electrically tunable layer-hybridized trions in doped WSe$_2$ bilayers

TL;DR

This paper demonstrates the electrical tunability of layer-hybridized trions in doped WSe$_2$ bilayers, revealing how electric fields influence trion energy states and photoluminescence properties, advancing optoelectronic control in atomically-thin semiconductors.

Contribution

It combines microscopic theory with experiments to show how out-of-plane electric fields control the energetic ordering and PL signatures of layer-hybridized trions in WSe$_2$ bilayers.

Findings

Electric field modifies trion energy landscape.

Distinct PL signatures for intralayer-like and interlayer-like trions.

Pronounced Stark red-shift in PL peaks at high doping asymmetry.

Abstract

Doped van der Waals heterostructures host layer-hybridized trions, i.e. charged excitons with layer-delocalized constituents holding promise for highly controllable optoelectronics. Combining a microscopic theory with photoluminescence (PL) experiments, we demonstrate the electrical tunability of the trion energy landscape in naturally stacked WSe$_2$ bilayers. We show that an out-of-plane electric field modifies the energetic ordering of the lowest lying trion states, which consist of layer-hybridized $\Lambda$-point electrons and layer-localized K-point holes. At small fields, intralayer-like trions yield distinct PL signatures in opposite doping regimes characterized by weak Stark shifts in both cases. Above a doping-asymmetric critical field, interlayer-like species are energetically favored and produce PL peaks with a pronounced Stark red-shift and a counter-intuitively large intensity arising from efficient phonon-assisted recombination. Our work presents an important step forward in the microscopic understanding of layer-hybridized trions in van der Waals heterostructures and paves the way towards optoelectronic applications based on electrically controllable atomically-thin semiconductors.