1 Introduction
Fig. 1 a Theoretical limit PCE for single junction and c-Si-based double junction solar cells [5,6]. b Experimental PCE evolution of PSK/c-Si TSC reported by literature, together with the schematic of PSK/c-Si TSC shown in the inset. c Equivalent circuits of 2 T PSK/c-Si TSC. Top is a recombination junction (RJ) case, and bottom is a tunnel junction (TJ) case |
2 Physics and calculation methodology
Table 1 Overview of numerical calculation methods for electromagnetic fields |
Technology | Methodology | Form | Characteristics | Refs. |
---|---|---|---|---|
Frequency Domain | FEM | Differential | Flexible discrete elements Sparse symmetric matrix facilitates the solution Accurate simulation for the interaction between the medium of complex structures and electromagnetic fields May require more storage space and computation time | [64, 65] |
MoM | Integral | Suitable for arbitrary shapes and non-uniformity problems Electromagnetic calculations limited to surfaces May lead to increased difficulty in solving very large matrices | [66] | |
Time Domain | FDTD | Differential | Using Maxwell’s equations as a starting point Simulation of wave propagation and the interaction between light and matter in a computerized digital space Calculation area involves not only the surface, but also the interior Too fine a mesh can lead to a huge amount of calculations | [62, 63, 67,68,69,70,71] |
TMM | Differential | Huygens-based wave propagation model A method for calculating the propagation of light in multilayer films Complex multi-beam superimposed interference processes in matrix form Oversimplification of non-vertical incidence and multiple scattering | [72,73,74,75] | |
TDIE | Integral | Accurate simulation calculations for surfaces and interfaces Post-storage of time to complete deferred integration, which greatly increases the storage time and space | [76] |
3 Light harvesting management
3.1 Single junction solar cell
Fig. 2 Simulation of the single junction solar cell. Schematic diagram of (a1) light reflection from a planar PSK solar cell and (a2) light scattering from a textured PSK interface; (a3) Calculated curves of light absorption for three different structures. AR, anti-reflection. Reproduced with permission [114]. Copyright 2020, American Chemical Society. Schematic diagram of (b1) the full-planar SHJ cell, (b2) SHJ cell with a single texture at the bottom, (b3) SHJ cell with a double texture at the top and bottom; (b4) EQE (solid curves) and reflectance (R, dashed curves) spectra obtained from optical simulations of three structures (Flat/Flat, Flat/Tex, Tex/Tex). Reproduced with permission [115]. Copyright 2017, Elsevier B.V |
3.2 PSK/c-Si double junction solar cell
Fig. 3 Calculation of the PSK/c-Si double junction solar cell. (a1-6) Tandem structures with different roughnesses and their corresponding theoretical JSCs. AR, anti-reflection. Reproduced with permission [119]. Copyright 2016, Optical Society of America. (b1) Schematic diagram of just the c-Si bottom surface as a textured pyramid, (b2) reflection mechanism inside the c-Si cell, and (b3) vector distribution of light reflection in 3-dimensions for the bottom pyramid (λ = 1100 nm, P = 5.0 μm, and H = 3.0 μm). P, period; H, height; α, inclination angle of the pyramid. Reproduced with permission [62]. Copyright 2018, John Wiley & Sons, Ltd. (c1) Schematic diagram of planar and conformal structures, and (c2) quantitative analysis of specific JSC losses. R, reflection. Reproduced with permission [120]. Copyright 2019, American Chemical Society |
3.3 Quasi-conformal structures
Fig. 4 Theoretical simulation of the conformal and quasi-conformal PSK/c-Si TSC. Power density distribution of PSKs (a1) growing along the substrate normal and (a2) growing along the local surface normal (λ = 750 nm). Reproduced with permission [68]. Copyright 2020, American Chemical Society. (b1) Simulation model of sine structure. AR, anti-reflection. (b2) light absorption results of planar and sine structures. R, reflection. Reproduced with permission [64]. Copyright 2021, De Gruyter. The light absorption (Abs) intensity distribution of (c1) conformal and (c2) quasi-conformal structures (λ = 600 nm). The red solid curves represent the integral of light absorption in the direction of the pyramid height, the dotted lines represent the division between tip and valley, and Δα is the difference between the inclination of PSK and Si pyramid. Reproduced with permission [71]. Copyright 2020, Wiley-VCH GmbH |
3.4 Bifacial properties
Fig. 5 Simulation of the bifacial PSK/c-Si TSC. (a1) Schematic diagram of the actual bifacial working environment. RA, albedo; Irr, irradiance. Reproduced with permission [126]. Copyright 2021, Elsevier Ltd. (a2) Albedo curves formed by different types of ground. Reproduced with permission [127]. Copyright 2019, Elsevier B.V.. (b1) Principles of CML formation in a bifacial TSC, the left is monofacial TSC and the right is bifacial TSC. Alb, albedo. (b2) Calculated bifacial tandem (BT) efficiencies under different bandgaps and albedo conditions after CML correction. (c1) Diagram of ultrathin c-Si optimized for top-cell and bottom-cell current matching. (c2) TSC efficiencies obtained for three different thicknesses (25, 100, and 250 μm) of c-Si bottom-cells at various albedos |
4 Energy yield
4.1 Monofacial PSK/c-Si TSC
Fig. 6 Yearly energy yield for (a1) 30° and (a2) 90° solar cell orientation. Three different locations (Washington, Golden, and Phoenix) and four different cell types (A, B, C, and D) are compared here. LM, light management. Reproduced with permission [18]. Copyright 2018, The Royal Society of Chemistry. Solar spectral irradiance under the influence of weather in (b1) Netherlands and (b2) Colorado. The inset of (b1) illustrates the variation of the broad spectral distribution (1) at midday in summer with the standard spectrum (AM1.5G) in shades of gray, (2) during a winter morning, (3) during a summer day with high relative humidity, and (4) at dawn. The upright triangles and the squares in (b2) correspond to the course of clear sky days measured in winter and in summer, respectively. Reproduced with permission [136]. Copyright 2016, American Chemical Society. Time-dependent (c1) hourly global irradiance and (c2) PCEs of the PSK/c-Si TSC from January to December. Reproduced with permission [137]. Copyright 2019, Optical Society of America |
4.2 Bifacial PSK/c-Si TSC
Fig. 7 (a1) Schematic of energy yield for bifacial PSK/c-Si TSC. Reproduced with permission [138]. Copyright 2019, Optical Society of America. (a2) Annual energy yield for monofacial and bifacial PSK/c-Si TSC modules simulated under different luminescent coupling. Reproduced with permission [130]. Copyright 2021, Wiley-VCH GmbH. (b) Energy yield for monofacial and bifacial 2 T PSK/c-Si TSC versus PSK bandgaps and ground conditions. Reproduced with permission [41]. Copyright 2021, Springer Nature. (c) Distribution of the photon flux versus the effective albedo for different scenarios. Reproduced with permission [82]. Copyright 2019, Elsevier Inc. |