Solar Mini-modules Research Articles

Modulating Buried Interface to Achieve an Ultra‐High Open Circuit Voltage in Triple Cation Perovskite Solar Cells

AbstractThis work proposes a methodology to increase the open‐circuit voltage of perovskite solar cells via modulating the buried interface using π‐conjugated molecules, featuring a push‐pull electronic structure configuration. In the planar perovskite solar cells using tin oxide nanocrystal as an electron transport layer, the 2‐methyl‐1‐aminobenzene derivatives with 4‐(Heptafluoropropan)‐2‐methylaniline notable not only reduce the interfacial energy barrier but also passivate the defects at the buried interface. This modulation enhances the open circuit voltage of Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 (bandgap ≈1.60 eV) perovskite solar cell to a high value of 1.241 V and thus the power conversion efficiency to 24.16% under standard testing condition. An even higher efficiency of 25.11% can be achieved when employing in the Cs0.05MA0.05FA0.9PbI3 (bandgap ≈1.54 eV) perovskite solar cell. The open circuit voltage (1.241 V) is among the highest in triple‐cation perovskite solar cells which reaches 95% Shockley–Queisser limit. A solar‐to‐CO conversion efficiency of 11.76% can be achieved in the fabricated perovskite solar minimodule driven carbon dioxide electrolyzer. This demonstrates the potential of utilizing perovskite solar cells for CO2 conversion as a clean and green energy environment.

Controlling Thin Film Morphology Formation during Gas Quenching of Slot-Die Coated Perovskite Solar Modules.

Transferring record power conversion efficiency (PCE) >25% of spin coated perovskite solar cells (PSCs) from the laboratory scale to large-area photovoltaic modules requires significant advances in scalable fabrication techniques. In this work, we demonstrate the fundamental interrelation between drying dynamics of slot-die coated precursor solution thin films and the quality of resulting slot-die coated gas-quenched polycrystalline perovskite thin films. Well-defined drying conditions are established using a temperature-stabilized, movable table and a flow-controlled, oblique impinging slot nozzle purged with nitrogen. The accurately deposited solution thin film on the substrate is recorded by a tilted CCD camera, allowing for in situ monitoring of the perovskite thin film formation. With the tracking of crystallization dynamics during the drying process, we identify the critical process parameters needed for the design of optimal drying and gas quenching systems. In addition, defining different drying regimes, we derive practical slot jet adjustments preventing gas backflow and demonstrate large-area, homogeneous, and pinhole-free slot-die coated perovskite thin films that result in solar cells with PCEs of up to 18.6%. Our study reveals key interrelations of process parameters, e.g., the gas flow and drying velocity, and the exact crystallization position with the morphology formation of fabricated thin films, resulting in a homogeneous performance of corresponding 50 × 50 mm2 solar minimodules (17.2%) with only minimal upscaling loss. In addition, we validate a previously developed model on the drying dynamics of perovskite thin films on small-area slot-die coated areas of ≥100 cm2. The study provides methodical guidelines for the design of future slot-die coating setups and establishes a step forward to a successful transfer of solution processes towards industrial-scale deposition systems beyond brute force optimization.

Fabrication of Efficient Perovskite Solar Minimodules with a High Geometric Fill Factor of 96% via a Nanosecond Laser

The low‐cost perovskite solar cell has become the next‐generation photovoltaic. However, compared to the high efficiency of the small‐area perovskite solar cells, the large‐area perovskite solar modules (PSMs) have still been struggling for the performance. In addition to preventing the decline in quality of each functional layer after upscaling, another key point is to construct a high geometric filling factor (GFF) for an efficient PSM. Herein, a “back‐scribing” technique is developed by using a low‐cost nanosecond laser scribing from the back side of substrates. The “back‐scribing” technology can clean up the scribing channels greatly, enabling an effective connection with a small damaged area. With precise control of the laser parameters for the scribing of P1, P2, and P3, a high GFF of 96% is achieved, resulting in a high power conversion efficiency of 19.97% with an aperture area of 16 cm2 for the PSM. By this means, the efficiency loss is minimized (<10%) when upscaling a small device to a large‐area solar module.

Low-Cost Fabrication of Efficient Perovskite Photovoltaics Using Low-Purity Lead Iodide via Powder Engineering

Low cost is the eternal theme for any commercial production. Numerous efforts have been explored to realize low-cost, high-efficiency perovskite solar cells (PSCs), such as replacing the traditional spin-coating method with an economical printing strategy, simplifying the device structure, reducing the number of functional layers, etc. However, there are few reports on the use of low-cost precursors. Herein, we enable the low-cost fabrication of efficient PSCs based on a very cheaper low-purity PbI2 via powder engineering. The low-purity PbI2 is blended with formamidinium iodide followed by dissolving in a 2-methoxyethanol solvent, and then, the high-quality FAPbI3 powders are formed via an inverse temperature crystallization process and solvent washing after several simple processes to reduce the impurities. As a result, the devices fabricated using the as-synthesized black powders based on the low-purity PbI2 exhibit a champion power conversion efficiency (PCE) of 23.9% and retained ∼95% of the initial PCE after ∼400 h of storage in the conditions of 25 ± 5 °C and 25 ± 5 RH% without encapsulation. In addition, the upscaling fabrication of a 5 cm × 5 cm solar minimodule also demonstrates an impressive efficiency of 19.5%. Our findings demonstrate an economic strategy for the commercialization of PSCs from the perspective of low-cost production.

Development of high-efficiency lightweight and flexible CIS-based solar minimodules

軽く，曲げることも可能な太陽電池は，2022年時点で世界の太陽光発電シェア95％を占めている従来の結晶Si系太陽電池の導入が難しい場所への設置をも可能にし，再生可能エネルギーのさらなる普及が期待される。CIS系材料は，薄膜型という特徴を活かした軽量で柔軟性を有する太陽電池の作製が可能であり，従来型の太陽電池とは異なる市場形成も期待される。ここでは，太陽電池としてはもちろんのこと，センサや水素生成など，さまざまなエネルギー変換デバイスへの応用も可能なCIS系材料の魅力についても紹介する。

A Self‐Assembled Vertical‐Gradient and Well‐Dispersed MXene Structure for Flexible Large‐Area Perovskite Modules

AbstractAdvancing hole transport layers (HTL) to realize large‐area, flexible, and high‐performance perovskite solar cells (PSCs) is one of the most challenging issues for its commercialization. Here, a self‐assembled gradient Ti3C2Tx MXene incorporated PEDOT:PSS HTL is demonstrated to achieve high‐performance large‐area PSCs by establishing half‐caramelization‐based glucose‐induced MXene redistribution. Through this process, the Ti3C2Tx MXene nanosheets are spontaneously dispersed and redistributed at the top region of HTL to form the unique gradient distribution structure composed of MXene:Glucose:PEDOT:PSS (MG‐PEDOT). These results show that the MG‐PEDOT HTL not only offers favorable energy level alignment and efficient charge extraction, but also improves the film quality of perovskite layer featuring enlarged grain size, lower trap density, and longer carrier lifetime. Consequently, the power conversion efficiency (PCE) of the flexible device based on MG‐PEDOT HTL is increased by 36% compared to that of pristine PEDOT:PSS HTL. Meanwhile, the flexible perovskite solar minimodule (15 cm2 area) using MG‐PEDOT HTL achieve a PCE of 17.06%. The encapsulated modules show remarkable long‐term storage stability at 85 °C in ambient air (≈90% efficiency retention after 1200 h) and enhanced operational lifetime (≈90% efficiency retention after 200 h). This new approach shows a promising future of the self‐assembled HTLs for developing optoelectronic devices.

Lightweight and flexible Cu(In,Ga)Se2 solar minimodules: toward 20% photovoltaic efficiency and beyond

Lightweight and flexible photovoltaic solar cells and modules are promising technologies that may result in the wide usage of light-to-electricity energy conversion devices. This communication presents the prospects of Cu(In,Ga)Se2 (CIGS)-based lightweight and flexible photovoltaic devices. The current status of flexible CIGS minimodules with photovoltaic efficiency values greater than 18% and future directions to enhance their efficiency values toward >20% are discussed. The effects of cell separation edges, which are formed through a mechanical, laser, or photolithography scribing process used to fabricate solar cells and modules, on the device performance are also discussed. We found that mechanically scribed CIGS device edges, which are present in conventional solar cells and modules, cause deterioration of device performance. In other words, further improvement is expected with appropriate passivation/termination treatment of the edges or replacing mechanical scribing with a damage-free separation process.

Blade‐Coated Solar Minimodules of Homogeneous Perovskite Films Achieved by an Air Knife Design and a Machine Learning‐Based Optimization

Perovskite solar technology stands on three different pillars: efficiency, stability, and processability. Focusing on processability, the field demands the achievement of optoelectronic grade active layers with high uniformity fabricated by industry‐compatible methods. Herein, the design and implementation of an air knife on a blade coating deposition system, which allows controlling the evaporation rate of the solvents improving the crystallization and uniformity of perovskite films in a p–i–n device are reported. The effect of doctor blade operational parameters is studied using image analysis combined with a machine learning method to identify the most relevant processing variables leading to a uniform perovskite layer with optimal thickness. After implementing the air knife system and finding the best processing conditions, a special perovskite solar minimodule enabling the evaluation of single inner subcells is fabricated. These perovskite subcells reach an average efficiency of 10.1% and remarkably all the subcells deviate less than 20% from this value over a large‐area substrate. These results demonstrate the promising potential of this fabrication method for low cost and high deposition rate photovoltaic devices, which is on the path to mass production.

High‐Performance Organic Solar Modules via Bilayer‐Merged‐Annealing Assisted Blade Coating

Although encouraging progresses being made on the spin-coated prototype cells, organic solar cells still face significant challenges, yet to be explored, for up-scaling the multi-stacked photoactive layers in the construction of large area modules. Herein, high-performance opaque and semitransparent organic solar modules are developed via a bilayer-merged-annealing (BMA) assisted blade-coating strategy, achieving the impressive efficiencies of 14.79% and 12.01% with respect to active area of 18.73 cm2 , which represent the best organic solar minimodules so far. It is revealed that BMA strategy effectively resolves the de-wetting issues between polar charge transport layer solution and non-polar bulk heterojunction blends, hence improving the film coverage, along with electronic and electric contacts of multi-stacked photoactive layers. As results, organic solar modules coated under ambient condition successfully retain the high-efficiency of small area cells upon 312 times area scaling-up. Overall, this work provides a facile and effective method to fabricate high-performance organic solar modules under ambient condition. This article is protected by copyright. All rights reserved.

Modulating crystal growth of formamidinium–caesium perovskites for over 200 cm2 photovoltaic sub-modules

Upscalable fabrication of efficient and stable perovskite solar modules is urgently needed for commercialization. Here we introduce methylammonium chloride additives in the co-solvent system of N-methyl-2-pyrrolidone/N,N-dimethylformamide to control the formation of intermediate phases during the growth of formamidinium–caesium lead triiodide perovskite films. We achieve high-quality films upon drying without the use of anti-solvent. By implementing bulk and surface passivation, champion efficiencies of 24.02% for a small-sized solar cell and 20.5% for a 5 cm × 5 cm solar mini-module on an aperture area of 22.4 cm2 (geometric fill factor ∼ 96%) are achieved by spin-coating. The fully blade-coated perovskite solar sub-module demonstrates a champion efficiency of 15.3% on an aperture area of 205 cm2. The solar mini-module exhibits impressive operational stability with a T80 lifetime of over 1,000 h at maximum power point tracking under continuous light illumination. Upscaling perovskite solar cells requires control of the crystallization of perovskite films over large areas. Here, the authors tailor the composition of the precursor ink and achieve 15.3% efficient solar cells over a 205 cm2 area without the use of anti-solvent.

Fully Spray-Coated Perovskite Solar Minimodules via a Vacuum-Flash Assisted Solution Process

Fully Spray-Coated Perovskite Solar Minimodules via a Vacuum-Flash Assisted Solution Process

Light‐Soak Stable Semitransparent and Bifacial Perovskite Solar Cells for Single‐Junction and Tandem Architectures

Semitransparent perovskite solar cells (ST‐PSCs) are very attractive due to their potential applications in single junctions for building‐integrated photovoltaics (BIPV) and in tandem PV technology using low‐bandgap bottom solar cells. Despite the high efficiency achieved, the ST‐PSCs still suffer low bifaciality, which can limit their overall energy yield for application in BIPV technologies. Furthermore, the knowledge on the long‐term light‐soaking stability of the ST‐PSC from both illumination sides is required to optimize the energy production in the long term. p−i−n ST‐PSCs and semitransparent perovskite solar minimodules with comparable and high efficiencies when illuminated from either the rear or the front sides, resulting in the highest reported bifaciality factor of 97%, are demonstrated. A bifacial equivalent power output of 21.3 W m−2 is achieved for ST‐PSCs under 1 sun illumination on the front side, while using a white back reflector from the rear side with 33.5% reflected albedo. However, the side of illumination has a big impact on the light‐soak stability of the ST‐PSCs. It is observed that the ST‐PSC provides more stable output power under illumination from the rear side (n‐side) of the stack.

Physical and chemical aspects at the interface and in the bulk of CuInSe2-based thin-film photovoltaics.

Chalcopyrite CuInSe2 (CISe)-based thin-film photovoltaic solar cells have been attracting attention since the 1970s. The technologies of CISe-based thin-film growth and device fabrication processes have already been put into practical applications and today commercial products are available. Nevertheless, there are numerous poorly understood areas in the physical and chemical aspects of the underlying materials science and interfacial and bulk defect physics in CISe-based thin-films and devices for further developments. In this paper, current issues in physical and chemical studies of CISe-based materials and devices are reviewed. Correlations between Cu-deficient phases and the effects of alkali-metals, applications to lightweight and flexible solar minimodules, single-crystalline epitaxial Cu(In,Ga)Se2 films and devices, differences between Cu(In,Ga)Se2 and Ag(In,Ga)Se2 materials, wide-gap CuGaSe2 films and devices, all-dry processed CISe-based solar cells with high photovoltaic efficiencies, and also fundamental studies on open circuit voltage loss analysis and the energy band structure at the interface are among the main areas of discussion in this review.

Light-induced performance increase of carbon-based perovskite solar module for 20-year stability

Improving stability has become one of the most important objectives in the practical application of perovskite photovoltaics. Here, we develop encapsulated mesoporous-carbon perovskite solar mini-modules that retain more than 92% of their initial performance after 3,000 h of damp-heat aging at 85°C/85% relative humidity, while maintaining 90% of the initial value (T90) for 3,260 h, equivalent to 20-year stability in outdoor use. This stability is attributed to the light-induced performance increase phenomenon. The mechanism is associated with the organic molecules 5-ammoniumvaleric acid and methylammonium forming a quasi-2-dimensional perovskite/metal oxide interface with a positive effect on charge transport and ion migration. This work extends our present understanding of the mechanism underlying the light-induced performance and stability increase.

Recent Progress on Metal Halide Perovskite Solar Minimodules

The rapid development of perovskite solar cells (PSCs) in view of efficiency during the past decade has made this emerging photovoltaic (PV) technology a promising competitor in the PV market. In the next step, PSCs need be manufactured into module scale to meet the commercialization requirements for further practical application. Demonstrations of perovskite solar modules (PSMs) and their improvements in efficiency and stability have recently become an intense area of research activities. Minimodules with the size suitable for laboratory investigation are naturally recognized as a desirable model for the study of PSMs. Herein, the recent progress and challenges in perovskite solar minimodules and the efforts to improve their scalable fabrication, efficiency, and stability are reviewed. Minimodule architectures, minimodule fabrication, and progress in the scalable deposition of perovskite and charge‐transport layers as well as minimodule encapsulation are also discussed.

Defect compensation in formamidinium–caesium perovskites for highly efficient solar mini-modules with improved photostability

Formamidinium–caesium mixed-cation perovskites have shown better thermal stability than their methylammonium-containing counterparts but they suffer from photoinstability induced by iodide migration and phase segregation. Here we improve their photostability by adding slightly excessive AX (at a molar percentage of 0.25% to Pb2+ ions), where A is formamidinium or caesium and X is iodine. The excessive AX does not improve the initial solar cell efficiency. It compensates iodide vacancies and suppresses ion migration and defects generation during long-term illumination by around tenfold compared with AX-deficient devices. Consequently, generation of hole traps and phase segregation is impeded, with the former limiting solar cell efficiency after degradation. The perovskite mini-modules reached a certified stabilized efficiency of 18.6% with an aperture area of ~30 cm2, corresponding to an active area efficiency of 20.2%. The mini-module maintains 93.6% of the initial efficiency after continuous operation under 1 sun illumination for >1,000 h at 50 ± 5 °C in air. Methylammonium-free perovskite solar cells have achieved promising efficiency and thermal stability yet iodide migration limits their operational stability. Deng and colleagues show that an excess of formamidinium or caesium iodide precursor suppresses iodide vacancies preventing ion migration and eventually the generation of hole traps during device operation.

One-dimensional Sb2Se3 enabling ultra-flexible solar cells and mini-modules for IoT applications

Power supply equipment, employed in the Internet of Things (IoT) for instance, calls for efficient harvesting of solar energy from the environment sustainably. Sb 2 Se 3 enjoys the advantages of unique one-dimensional crystal structure and low-temperature film growth, enabling the fabrication of flexible and lightweight solar cells. Therefore, Sb 2 Se 3 solar cells are expected to have intrinsic advantages in powering IoT sensors. Herein, the device configuration and film fabrication of flexible Sb 2 Se 3 solar cell was optimized and an efficiency up to 6.13% and power-per-weight of 2.04 W g -1 were obtained, both of which are the highest records for flexible Sb 2 Se 3 solar cells. Benefitting from the intrinsically high flexibility of Sb 2 Se 3 and the thin flexible substrate, our device retained 96% of its initial performance after 1000-times bending at the extremely small curvature radius of 0.5 mm. Furthermore, the first Sb 2 Se 3 mini-module (25 cm 2 area) was constructed and its application in powering a blue LED under all weather conditions and a flower monitor (IoT sensors) was demonstrated. This work opens an avenue toward flexible Sb 2 Se 3 solar cells and points out its future research direction. Solar cells, with high energy density and reliability, can serve as the power source for the sensors of the Internet of Things (IoT) sensor. Combining the intrinsically high flexibility of Sb 2 Se 3 and careful analysis of stain distribution, lightweight and ultra-flexible Sb 2 Se 3 solar cells and mini-modules were obtained and successfully applied to IoT sensors as energy supply. • The analysis of material mechanics and stain distribution guide the design of ultra-flexible Sb 2 Se 3 solar cells. • The flexible Sb 2 Se 3 solar cells exhibit high efficiency of 6.13%, high power-per-weight of 2.04 W g -1 . • The flexible Sb 2 Se 3 solar cells keep 96% of the initial PCE after 1000-times bending at a curvature radius of 0.5 mm. • The large-area (~ 25 cm 2 ) flexible Sb 2 Se 3 solar mini-modules are successfully applied for power supply of IoT sensors.

The investigation of PV systems quantum efficiency in various irradiation condition

We confirm the importance of the angle of incidence of direct solar radiation on external quantum efficiency of solar mini-modules consisting of the following closed structure: silicon solar cells with antireflective coating (Si + ARC1)/EVA (ethylene–vinyl acetate) foil /glass with or without antireflective coating (ARC2). The results are consistent with a proposed model of an optical module with a specific architecture.A study of the electrical parameters of photovoltaic modules as a function of the angle of incidence of radiation was carried out using a solar class AAAA simulator. The changes in short circuit current Isc were calculated relative to Isc for the module fully illuminated by light perpendicular to the surface. A decrease in Isc was recorded for modules containing textured glass or Flat glass. The use of antireflective coating ARC2 on glass in module structure increases external quantum efficiency and photogeneration current under AM1.5 global spectrum at 1000 W/m2 light intensity at temperature 25 °C, mainly for the angle of incidence of 35°.

High-throughput analysis of the ideality factor to evaluate the outdoor performance of perovskite solar minimodules

Halide perovskite solar cells exhibit a unique combination of properties, including ion migration, low non-radiative recombination and low performance dependence on temperature. Because of these idiosyncrasies, it is debatable whether standard procedures for assessing photovoltaic technologies are sufficient to appropriately evaluate this technology. Here, we show a low dependence of the open-circuit voltage on the temperature of a MAPbI3 minimodule that allows a high-throughput outdoor analysis based on the ideality factor (nID). Accordingly, three representative power loss tendencies obtained from I–V curves measured with standard procedures are compared with their corresponding nID patterns under outdoor conditions. Therefore, based on the linear relationship between T80 and the time to reach nID = 2 (TnID2), we demonstrate that nID analysis could offer important complementary information with important implications for outdoor development of this technology, providing physical insights into the recombination mechanism dominating performance, thus improving the understanding of degradation processes and device characterization. The investigation of perovskite solar modules under outdoor conditions could provide insights into device operation and degradation in the field. Velilla et al. report on the potential of the ideality factor to analyse outdoor device performance evolution over time, distinguish between degradation modes and estimate the lifetime.

Fabrication of Cost-Effective Reduced Graphene Oxide Based Parallel Grids Embedded Dye-Sensitized Solar Mini-Modules

Cost-effective, parallel grids embedded dye-sensitized solar mini-modules were fabricated successfully by utilizing reduced graphene oxide (rGO) and rGO-silver (rGO-Ag) nanocomposites as grid current collectors. The pure rGO grids embedded dye-sensitized solar mini-module showed a maximum power conversion efficiency of 4.10% with improved fill factor, circumvented iodide/triiodide electrolyte corrosion, and reduced the module power loss significantly. Electrochemical impedance spectroscopy studies revealed that the 1:1 wt% ratio rGO-Ag nanocomposite grids improved the module's electron diffusion length, carrier mobility and lifetime, and produced a higher open-circuit voltage (Voc) as compared with the pure silver grids in the dye-sensitized solar mini-module.