Fig. 1: Phonon-assisted upconversion enhancement in a 5.5° twisted bilayer WSe2.
From: Phonon-assisted upconversion in twisted two-dimensional semiconductors
a Schematic of phonon-assisted upconversion mechanism. b Schematic of the device structure. c, d PL (c) and UPC (d) spectra of ML1(dark blue lines), ML2 (blue lines) and TBL (yellow lines), gray dotted lines indicate intensities normalized as 1. e, f PL (e) and UPC (f) maps of the corresponding bilayer sample in c and d, scale bar 5 μm
