Fig. 4
From: Recent progress of exciton transport in two-dimensional semiconductors
a (i) Illustration depicting a wrinkled WS\(_2\) monolayer and its corresponding energy diagram. (ii) PL intensity and energy image of a single WS\(_2\) monolayer crystal. (iii) PL spectra obtained under different tensile strains of 0 \(\%\), 1.7 \(\%\), and 3.3 \(\%\). (iv) Fitted PL spectra acquired at the top (top) and valley (bottom) regions of the wrinkled WS\(_2\) monolayer. b (i) AFM topography image showing a WSe\(_2\) monolayer transferred onto a nanowire. (ii) Illustration demonstrating the behavior of photo-generated excitons diffusing along a quasi-1D channel. (iii) Spatially and temporally resolved distribution of photogenerated excitons, obtained through simulation (top) and experiment (bottom). (iv) Displacement of excitons in the x-axis and y-axis as a function of time. (v) Linewidth profile demonstrating spatially varying intervalley exciton–phonon scattering rate. (c) (i) Topography image (middle panel), along with an applied strain map (top panel), showing a WS\(_2\) monolayer transferred onto a micropillar. (ii) Illustration highlighting the behaviors of bright excitons and dark excitons in the presence of strain gradient. (iii) Spatially and temporally resolved distribution of dark excitons at different positions (spot A, B, and C), corresponding to distinct locations within the strain gradient region. (iv) Detailed time-dependent behavior analysis focusing on dark excitons at spot C. a Reproduced with permission [60]. Copyright [2022] Americal Chemical Society. b Reproduced with permission [61]. Copyright [2021] AAAS. c Reproduced with permission [62]. Copyright [2021] Springer Nature