Fig. 1. (Color online) (a) Schematic diagram of the RPP-MWs photodetector. (b) Schematic of the mechanism of carrier generation when visible and NIR light illumination is applied to the multi-layer core-shell RPP-MWs. (c) Schematic lattice structure of the RPP with different values of n in different phases of the RPP-MWs.

Fig. 2. (Color online) Characterization of the RPP-MWs. (a) SEM image of a single RPP-MW. (b) XRD spectrum of the RPP-MWs. (c) Raman spectrum of the RPP-MWs, with the characteristic peaks of Si marked with blue squares and the signals from the RPP-MWs marked with red stars. Raman spectra of (d) PEA₂PbI₄ (n = 1) and MAPbI₃ (n = ∞) and (e) original RPP-MWs and MWs cauterized for 10 s and (f) for 60 s. (g) PL spectrum of the RPP-MWs used to find the optimal excitation wavelength, excited at 200 nm. (h) PL spectrum of the RPP-MWs, excited at 396 nm. (i) Schematic band structure of the RPP-MWs.

Fig. 3. (Color online) Photoresponse performance comparison of the 2D-RPP and RPP-MW photodetectors. (a) Current curve of the 2D-RPP photodetector. Inset is the optical microscopic photograph of the 2D-RPP photodetector. (b) Responsivity curve of the 2D-RPP photodetector. (c) The power density of monochromatic light used in the tests. (d) Current curve of the RPP-MW photodetectors. Inset is the optical microscopic photograph of the RPP-MWs photodetector. (e) Responsivity curve of the RPP-MWs photodetector. (f) TRPL spectra of 2D-RPP and RPP-MWs.

Fig. 4. (Color online) (a, b) I–V characteristic curves and (c, d) switching tests of the RPP-MWs photodetector tested at 550 nm and 1064 nm, respectively. The insets show the time-resolved current curves after illumination for 60 s. (e, f) Schematic band structure of the RPP-MWs photodetector when tested at visible light and NIR light, respectively.