Fig. 1. (Color online) (a) Schematic presentation of the conventional design of a flexible planar perovskite light-emitting device (on the left) and flexible perovskite device with a distributed Si NWs electrode (on the right). (b) Fabrication workflow of a flexible PeLEC with a distributed Si NW-based electrode. (c) Photo of the bent PeLEC membrane with a distributed Si NW-based electrode; scale bar is 1 cm.

Fig. 2. Isometric SEM images of (a) an etched Si NW array; (b) a Si NWs array after PDMS coating; (c) the revealed top parts of Si NWs in the partially etched PDMS membrane. Inset in (a) shows a cross-section view SEM image of an as-fabricated Si NW array. The scale bars for all images are 2 µm.

Fig. 3. (Color online) (a) Schematic view of the considered semiconductor system. (b) The calculated system band diagram at the Si NWs/CsPbBr₃ interface (transverse coordinate). (c) The system’s calculated current density and radiative recombination quantum efficiency dependencies over the applied voltage (for the fixed H_emb = 500 nm, D_NW = 100 nm, L = 1000 nm, P = 0.2 μm⁻²). Insert shows the distribution of radiative recombination rate in the cross-section of the PeLEC structure. The calculated maps of quantum efficiency on (d) NW surface density and NW diameter (for the fixed H_emb = 500 nm and L = 1000 nm) and (e) perovskite thickness and NW height embedded into the active perovskite layer (for the fixed D_NW = 75 nm and P = 0.2 μm⁻²).

Fig. 4. (Color online) (a) Cross-sectional SEM images of perovskite layers, spin-coated at 600 and 1200 r/mim on Si NWs membranes (presented in artificial colors for clarity); the insets show the corresponding top-view PL images. (b) PL spectra of CsPbBr₃ layers obtained with different coating speeds. (c) Isometric SEM images of CsPbBr₃ layers spin-coated on Si NWs membranes at 600 r/mim and annealed at 60 and 200 °C; the insets show the corresponding top-view PL images. (d) PL spectra of CsPbBr₃ layers obtained with different temperatures of annealing. (e) XRD patterns for a series of CsPbBr₃ perovskite films spin-coated on Si NW membranes and planar Si substrate. The calculated positions of the Bragg reflections related to the CsPbBr₃ (COD CIF file ID: 4510745)^[47] and Cs₄PbBr₆ (COD CIF file ID: 4002857)^[48] phases are shown by black and green vertical marks, correspondingly.

Fig. 5. (Color online) (a) Сross-sectional SEM image of PeLEC-on-Si device (in artificial colors for clarity). Photo of (b) PeLEC-on-Si and (c) flexible PeLEC during EL measurements (acquired at 5 and 7.3 V applied voltage, respectively). (d) Luminance−voltage (red curve) and current density−voltage (black curve) dependencies for PeLEC-on-Si device, (e) EL spectra of PeLEC-on-Si and flexible PeLEC devices. (f) PeLEC-on-Si and flexible PeLEC I−V curves comparison.