20.0% Efficiency Si Nano/Microstructures Based Solar Cells with Excellent Broadband Spectral Response

Abstract

wileyonlinelibrary.comand short-wavelength spectral response is not good enough, mainly due to the large recombination loss of back surface fi eld (BSF) [ 2 ] and the high residual refl ectance at the front surface, [ 3 ] respectively. To achieve the excellent broadband spectral response of the Si based solar cells, it is necessary to further improve the optical and electrical properties of the rear surface as well as the front surface. By introducing passivation dielectric thin fi lms at the rear surface, Green group [ 4 ] has successfully fabricated a 22.8% effi cient passivated emitter and rear cell (PERC) with an area of 4 cm 2 , manifesting superior long-wavelength spectral response due to the low recombination velocity and high long-wavelength refl ectivity at the rear surface. [ 5 ] This longwavelength superiority has been recently employed in the photovoltaic industry for the mass production of 20.0% effi cient PERCs on commercial large-area (156 × 156 mm 2 ) Si wafers. [ 6,7 ] On the other hand, Si nanostructure array provides a promising approach to enhancing the energy harvesting in the shortwavelength range, for the near zero and small-angle-dependent refl ectivity in the short-wavelength region. [8][9][10][11][12][13][14][15] By employing the well short-wavelength antirefl ection of the Si nanostructure array, many authors have made relative progresses in the cell performances of the Si nanostructures based solar cells. [16][17][18][19][20][21] But η 's of these Si nanostructures based solar cells are still not satisfi ed when comparing with those of the traditional solar cells, which is mainly attributed to the large surface recombination loss from the Si nanostructures. Surface passivation such as thermal SiO 2 , [ 4,11,22 ] SiN x :H by plasma enhanced chemical vapor deposition (PECVD), [ 23,24 ] and Al 2 O 3 by atomic layer deposition (ALD) [25][26][27] can effectively suppress the surface recombination by saturating the dangling bonds or forming the fi xed charges at and near the surface. Particularly, the stack SiO 2 /SiN x layers provide an excellent passivation for the Si nanostructures, [28][29][30] which benefi ts from the well surface passivation of the inner SiO 2 as well as the bulk passivation of the outer SiN x :H. The simultaneous surface and bulk passivation guarantee the well electrical performance of the Si nanostructures based solar cells.As a result, the passivated front Si nanostructures together with the passivated rear surface are able to provide the complementary spectral responses in both the short-wavelength and long-wavelength region, implying an effective way to achieve the excellent broadband spectral response of Si based solar cells. In this paper, 20.0% Effi ciency Si Nano/Microstructures Based SolarSpectral response of solar cells determines the output performance of the devices. In this work, a 20.0% effi cient silicon (Si) nano/microstructures (N/M-Strus) based solar cell with a standard solar wafer size of 156 × 156 mm 2 (pseudo-square) has been successfully fabrica...

Vacuum-Free, Room-Temperature Organic Passivation of Silicon: Toward Very Low Recombination of Micro-/Nanotextured Surface Structures

“…Second, we attempted to passivate nanopore−pyramid surfaces, which form nanopores on inclined plane of a pyramid with a larger surface area, as shown in Figure 4c,d. This Si micro-/ nanostructure-based solar cell possesses an excellent broadband spectral response due to the improved short-wavelength response, as recently reported by Shen et al 26 Figure 4e shows the τ eff evolution of both Nafion-passivated Si surface structures; the τ eff evolution trends are similar to those observed in Figure 1c. Note that the nanopore−pyramid surface presents a lower initial value of τ eff but a higher maximum value of τ eff than the pyramidal surface structure.…”

Controllable nanoscale inverted pyramids for highly efficient quasi-omnidirectional crystalline silicon solar cells

“…The J 0 are obtained as the values of 299.2 fA cm −2 , 284.7 fA cm −2 and 296.8 fA cm −2 for the NIP-A, NIP-B and NIP-C textured solar cells, respectively. The J 0 of the present NIPs' textured solar cells are obviously at a similar level and are lower than that (357.15 fA cm −2 ) of the c-Si nanowires/micro-pyramids based solar cell with the same device framework [22], which implies a reduced recombination loss of the n + emitter including the Auger and surface recombination for the smaller surface area enhancement ratio of NIPs.…”

“…Moreover, the double-sided stack SiO 2 /SiN x layers contribute to the excellent surface passivation effect. Our group [22] have previously confirmed that optimally annealed stack SiO 2 /SiN x layers could bring about an ultra-low surface recombination velocity of 18.3 cm s −1 , benefiting from the formation of more Si-O and Si-H bonds to suppress the dangling bonds in the Si/SiO 2 interface. In this study, we have also carried out the same optimal annealing process for the stack SiO 2 /SiN x layers to guarantee an excellent surface passivation effect and optical response (see supplementary information, figure S2) with an optimal rear stack layer thickness of ∼25 nm and ∼250 nm, respectively.…”

High-Efficiency Silicon Inverted Pyramid-Based Passivated Emitter and Rear Cells

“…As shown in Fig. 3b The stack SiO 2 (~2 nm)/SiN x (~75 nm) passivation for the Si IP-based n + emitter is an effective way for achieving well electrical performance of IP-based PERC and their passivation effect [1] and mechanism have been systematically studied in our previous work [14]. To show the electrical superiority of the stack Al 2 O 3 / SiN x passivation layers at the rear of our device, we Fig.…”

“…The stack SiO 2 (~ 2 nm)/SiN x (~ 75 nm) passivation for the Si IP-based n + emitter is an effective way for achieving well electrical performance of IP-based PERC and their passivation effect [ 1 ] and mechanism have been systematically studied in our previous work [ 14 ]. To show the electrical superiority of the stack Al 2 O 3 /SiN x passivation layers at the rear of our device, we investigate the influence of the different annealing and light-soaking conditions on the effective minority carrier lifetime ( τ eff ) with respect to the injection level ( Δn ), as shown in Fig.…”