Simple Solution‐Processed Approach for Nanoscale Coverage of Perovskite on Textured Silicon Surface Enabling Highly Efficient Perovskite/Si Tandem Solar Cells

Abstract

Nowadays, crystalline silicon (c-Si) solar cells account for more than 90% of the photovoltaic market due to the advantages of nonpollution, popularization of raw materials, low levelized cost, and high power conversion efficiencies (PCEs). The efficiency of c-Si solar cells based on the heterojunction back contact structure has reached up to 26.6%. [1] For single-junction solar cells, it is difficult to further improve their PCEs attributed to the Shockley-Queisser limit, which is 29.4% for c-Si solar cells. [2] Recently, perovskite/c-Si monolithic tandem solar cells (TSCs) have attracted extensive attention. Perovskite is considered to be the ideal top cell material because of its tunable bandgaps, high absorption coefficient, and various preparation methods. [3] The efficiency of devices has quickly increased from 3.8% to 25.2%. [4,5] Si solar cells have the advantages of intense short-circuit current and high absorption in longwave, suitable as the bottom cell. Perovskite/ c-Si TSCs combine Si cells with a bandgap of 1.12 eV and perovskite cells with a tunable bandgap of 1.5-2.3 eV to achieve spectral distribution absorption. [6-8] In theory, the ultimate efficiency of two-junction cells with full-spectrum matching can reach 43%, which is the dawn of the future photovoltaic industry. [9] In the past 5 years, the PCEs of the perovskite/c-Si monolithic TSCs have sharply increased from an initial 13.7% to a recently certified 29.15%, exhibiting the enormous potential of TSCs. [5,10] The early studies on perovskite/Si TSCs were carried out on the front surfacepolished silicon cells as the perovskite preparation process was mostly based on flat substrates. [10-18] However, nontextured surface could cause severe optical losses. To maximize the absorption of the solar spectrum and avoid the surface polishing step, many researchers have now joined in studying the growth of perovskite films on the fully textured silicon surfaces. [19-22] The incompatibility of silicon and perovskite solar cell (PSC) manufacturing processes has brought new challenges and opportunities for photovoltaic community. The difficulty lies in the large undulations of the silicon surface, and the ordinary solution route will cause serious enrichment of the perovskite precursor in the Si pyramid valley, which results in exposure of the Si pyramid tip. Moreover, due to the different wettability of perovskite precursor solutions to different substrate morphologies, the Si pyramid induces new difficulties for the growth of perovskite controllable film thickness. Up to now, the growth of perovskite on the fully pyramidtextured silicon surface can be summarized into three types: 1) Micrometer-thick perovskite full coverage; [19,20] 2) Dual-source coevaporation method combined with solution method; [21] and 3) Mechanical stacking. [22] For the first scenario, Hou et al. used

Interfacial and Permeating Modification Effect of n-type Non-fullerene Acceptors toward High-Performance Perovskite Solar Cells

“…The long-term stability of PSCs is still a most concerned issue. − To assess the operational stability of these devices, long-term stability was tested via the ISOS-D-1 protocol . As shown in Figure h, the control-encapsulated device maintains over 60% of its initial performance after 30 days of dark storage in ambient air (N 2 , 78%, O 2 , 21%) at RH 75% and RT 25 °C.…”

Monolithic perovskite/c-Si tandem solar cell: Progress on numerical simulation

“…The issue of light propagation and absorption in solar cells is ultimately a problem of solving electromagnetic field, for which there are many numerical methods, as shown in Table 1. The relatively mature kernels of simulation software are: FEM [64,65], MoM [66], which belong to frequency domain technique; FDTD [62,63,[67][68][69][70][71], TMM [72][73][74][75], and TDIE [76], which belong to time domain technique. Each method has its own features and limitations.…”

“…4(b1,2), a Si substrate with a sinusoidal structure not only makes the growth of PSK easy, but it has a lower reflection in the short-wavelength range and a higher EQE value compared to the planar structure, indicating that the substrate optimization can achieve superior optical performance. To overcome the PSK coverage issues on the pyramidal texture, quasi-conformal PSK layers were prepared by Wang et al [71], using starch additive engineering, and theoretical analysis was performed applying FDTD. As shown in Fig.…”

“…This invited review summarizes the progress of numerical simulation studies of PSK/c-Si TSC in terms of the methodology, light harvesting management, and energy yield (EY) aspects. Starting with the physical fundamentals of the methodology, we outline five commonly used software kernels (finite element method (FEM) [64,65], method of moments (MoM) [66], finite difference time domain (FDTD) [62,63,[67][68][69][70][71], transfer matrix method (TMM) [72][73][74][75], and time domain integral equation (TDIE) [76]) for calculating electromagnetic problems, and point out that integration of methods, optimization of modeling and parameter correction can effectively improve simulation accuracy. For the light harvesting management part, by analyzing the optical properties of single junction cell, double junction cell and quasi-conformal structure, we illustrate that the textured PSK/c-Si TSC has excellent PV performance.…”

Laminated Monolithic Perovskite/Silicon Tandem Photovoltaics

“…The use of both-side textured silicon solar cells-which are standard for silicon photovoltaics-would significantly reduce these reflection losses and improve light trapping. [19,[52][53][54] While it is challenging to cover conventional front-side textures of silicon substrates with pyramidal dimensions of ≈5 µm via spin-coating, recent studies indicate the possibility to realize enclosed films on adapted silicon solar cells textures (dimensions ≈1-2 µm) with particularly thick perovskite layers, [55][56][57] or on nanotextured silicon substrates. [58] Making use of such techniques, the lamination approach introduced in this work is expected to be compatible with textured silicon bottom solar cells.…”