It should be noted that although only b/Λ is given in the figure, the results are actually from a number of 2D parametrical sweep for both Λ (from 300 to 1,100 nm with step 50 nm) and b/Λ (from 0.5 to 1 with step 0.05), i.e., the 3D PV system has been simulated for hundreds of times in order to find the designs with the highest J tot. For
Selleck MGCD0103 each b/Λ, only the maximized J tot under an optimized Λ, which generally varies under different b/Λ, is recorded. Compared to the planar cell (i.e., b/Λ = 1) with J tot approximately 20.79 mA/cm2, two-dimensionally nanopatterning top junction always leads to a much higher J tot with a peak of 27.69 mA/cm2 (see red curve
for unpolarized case) at b/Λ = 0.75, Selleck LY2109761 Λ x = 450 nm, and Λ y = 850 nm. In addition, transverse electric (TE, i.e., electrical field E along y) and transverse magnetic (TM, i.e., E along x) incidences show identical max(J tot) due to the geometrical symmetry, while the value for unpolarized, i.e., (TE + TM)/2, is generally lower. To explore the physics behind the above observation, contour maps of max(J tot) versus Λ x and Λ y are given in Figure 2a,c for TM, TE, and unpolarized cases, respectively. In these figures, b/Λ = 0.75 is used according to the design of Figure 1 and the peaked J tot values in mA/cm2 have been marked directly. Comparing Figure 2 panels a and b, the photocurrent maps for TE and TM cases are mutually symmetrical with respect to the line of Λ y = Λ x . This is rational since it is completely equivalent to rotate either the electric polarization or the device by 90° in the x-y plane. This answers the question that why the curves (in blue) for TE and TM are undistinguishable in Figure 1b. However, J tot is not peaked under the same
grating pitches for TE or TM (see Figure 2a,b). A direct Branched chain aminotransferase consequence is that the maximal J tot for unpolarized illumination cannot reach the value under linear polarization. This can be seen from Figure 2c, where max(J tot) = 27.72 mA/cm2 (<28.05 mA/cm2 from linear case) is found at Λ x = 520 nm and Λ y = 930 nm. It should be noted that the peaked value and optimal pitches are slightly changed from Figure 1b since a finer sweep with Λ step of 10 nm is employed. Figure 2 Grating pitch optimization and absorption spectra. J tot versus Λ x and Λ y for (a) TM, (b) TE, and (c) (TE + TM)/2; (d) J tot versus Λ y at Λ x = 520 nm with planar case (wo, i.e., without nanopattern design) for reference; P abs versus Λ y and λ under (e) TM and (f) TE incidences, where Λ x = 520 nm. b/Λ = 0.75 (according to Figure 1) is used in all figures. Figure 2d plots J tot as a function of Λ y with b/Λ = 0.75 and Λ x = 520 nm for all interested polarizations conditions. Also inserted is the J tot of the planar system mentioned previously.