Figure 1a shows the schematics of the simulated unit of the proposed hybrid solar cells, which comprised vertically
aligned Si NWA coated with conformal thin layer of P3HT on supporting Si substrate. The simulated region of FDTD is represented by a dashed frame, in which perfect match layer (PML) boundary conditions as well as source are signed. Meanwhile, as shown in Figure 1b, a more realistic condition, under which the Si NWA learn more structure is fully infiltrated with P3HT, is also considered. The refractive indexes of silicon and P3HT used in this simulation see more are shown in Figure 1c,d. The parameters of this structure are the period of the square lattice P, Si core NWs diameter D, NW’s height H, and organic shell thickness T. By placing the periodic boundary conditions, the simulations were carried out in a unit cell to model the periodic square-array wire find more structure with substrate. In our simulation, the optimized geometry of silicon NWs on
flat Si substrate was fixed as P = 500 nm, D (SI) = 250 nm, and H = 5 μm . It has been confirmed that the Si NWA with this structure as mentioned has the most efficient light absorption. In order to simplify the calculation, the Si thin film is assumed infinitely thick with no transmission loss by using a PML adjacent underneath the Si film. Note that the transmission sensor was set at the bottom of Si NWA. Hence, the optical characteristics we discussed in the following mafosfamide sections are related to NWA (or P3HT/Si NWA). The absorption in the bottom Si substrate is not included. Meanwhile, the optical generation rates and ultimate photocurrents were also achieved to give an optical optimization and analysis of the proposed hybrid P3HT/Si NWA structure. Figure 1 Unit of P3HT/Si NWA hybrid solar cells and refractive indexes of silicon and P3HT. (a) Simulated unit of P3HT/Si NWA hybrid solar cells modeled in this study: conformal coating. (b) Simulated unit of P3HT/Si NWA hybrid solar cells modeled in this study:
full-infiltrated. (c) Refractive index of silicon. (d) Refractive index of P3HT. Results and discussion Figure 2a,b,c show the optical properties of P3HT/Si NWA hybrid system with various coating thicknesses of P3HT. As shown in Figure 2c, in the shorter wavelength region (<650 nm), one can find that the absorption of the P3HT/Si NWA system increases strongly as the thickness of the organic shell is increased. The absorptance of the NW/organic array reaches a maximum at the coating thickness of 80 nm. Further increasing the shell thickness will cause decrease of absorption, which is attributed to reflectance enhancement (Figure 2a) at this wavelength region. Due to the increase of photoactive material, the addition of organic coating can further decrease the transmission of P3HT/Si NWA structure in this wavelength region (Figure 2b).