Tandem Cells Research Articles

First-principles study of the structural, mechanical, electronic, optical, and elastic properties of non-toxic XGeBr3 (X=K, Rb, and Cs) perovskite for optoelectronic and radiation sensing applications

In this study, a comprehensive analysis of the structural, electronic, optical, and elastic properties of cubic perovskite structure XGeBr3(X=K,Rb,andCs) was carried out using GGA-PBE functional based density functional theory in CASTEP code. The simulated values of the lattice parameter were increased with the changing of X from K to Cs (a = 5.51 Å, 5.54 Å, and 5.59 Å respectively). All the compounds possessed direct band gaps and acquired values for the structures KGeBr3, RbGeBr3 and CsGeBr3 were 0.525 eV, 0.599 eV, and 0.708 eV, respectively. Furthermore, the atomic orbital's contribution to the formation of band structure was clarified thoroughly. The thermodynamic, as well as the mechanical stability, has been accomplished with the assurance of negative formation energy and Born-Huang approximation. In addition, a larger shearing modulus attained by CsGeBr3 manifests its strength. Moreover, all structures bear the proof of having ductility and existing central force inside the structures. Finally, the calculated anisotropic index notifies that all structures exhibit anisotropy with the trend of CsGeBr3 < RbGeBr3 < KGeBr3. This is also authenticated through the 3D anisotropy contour plot generated by utilizing ELATE software, which is for the first time in regard to the comparative scenario among them. With the investigation of the optical characteristics of the compounds XGeBr3, intriguing features such as broad absorption spectrum, high dielectric function and refractive index at zero photon's energy, and high conductivity have been affirmed accompanying the marginal value of loss function as well as reflectivity that elevates the probability of being employed in optoelectronic applications along with different absorber layers of tandem solar cells. In addition, these compounds could be used as radiation detectors since they have broad absorption at extreme ultraviolet rays.

Interface Reactive Sputtering of Transparent Electrode for High-Performance Monolithic and Stacked Perovskite Tandem Solar Cells.

Sputtered indium tin oxide (ITO) fulfills the requirements of top transparent electrodes (TTEs) in semitransparent perovskite solar cells (PSCs) and stacked tandem solar cells (TSCs), as well as of the recombination layers in monolithic TSCs. However, the high-energy ITO particles will cause damage to the devices. Herein, the interface reactive sputtering strategy is proposed to construct cost-effective TTEs with high transmittance and excellent carrier transporting ability. Polyethylenimine (PEI) is chosen as the interface reactant that can react with sputtered ITO nanoparticles,so that, coordination compounds can be formed during the deposition process, facilitating the carrier transport at the interface of C60/PEI/ITO. Besides, the impact force of energetic ITO particles is greatly alleviated, and the intactness of the underlying C60 layer and perovskite layer is guaranteed. Thus, the prepared semitransparent subcells achieve a significantly enhanced power conversion efficiency (PCE) of 19.17%, surpassing those based on C60/ITO (11.64%). Moreover, the PEI-based devices demonstrate excellent storage stability, which maintains 98% of their original PCEs after 2000 h. On the strength of the interface reactive sputtering ITO electrode, a stacked all-perovskite TSC with a PCE of 26.89% and a monolithic perovskite-organic TSC with a PCE of 24.33% are successfully fabricated.

Double Perovskite Tandem Solar Cells: Design and Performance Investigation of the Use of CABB and CCSC as Top and Bottom Cell Absorber Materials

Double Perovskite Tandem Solar Cells: Design and Performance Investigation of the Use of CABB and CCSC as Top and Bottom Cell Absorber Materials

Unveiling the Potential of Two-Terminal Perovskite/Organic Tandem Solar Cells: Mechanisms, Status, and Challenges.

Perovskite/organic tandem solar cells (PO-TSCs) demonstrate exceptional suitability for emerging applications such as building-integrated photovoltaics, wearable devices, and greenhouse farming. By leveraging the distinctive attributes of perovskite and organic materials, which encompass expanded solar spectrum utilization, chemically benign solubility, and soft nature, PO-TSCs position themselves as ideal candidates for high-performance semi-transparent photovoltaics (ST-PVs). Despite these advantages, their development significantly lags behind other perovskite-based counterparts, such as perovskite/perovskite, perovskite/silicon, and perovskite/Cu(In, Ga)Se2. To address existing challenges and unlock the full potential of PO-TSCs, an exploration of the fundamental mechanisms governing tandem photovoltaic devices is embarked. Delving into critical aspects such as charge generation/separation, energy level alignment, and material choices becomes pivotal for optimizing PO-TSC performance. The investigation of monolithic two-terminal PO-TSCs offers insights into achievements and barriers, recognizing the competitive landscape with other TSC counterparts. Further scrutiny of perovskite absorbers and organic absorbers in TSCs reveals strategies aimed at enhancing stability and efficiency. The discussion extends to interconnection layers, elucidating their role in optimizing light transmission and balancing carrier recombination. In conclusion, a compelling outlook on the dynamic landscape of PO-TSCs is presented, highlighting the remarkable efficiency progression and signaling their potential to revolutionize solar energy harvesting technologies.

Custom-tailored hole transport layer using oxalic acid for high-quality tin-lead perovskites and efficient all-perovskite tandems.

All-perovskite tandem solar cells (TSCs) have exhibited higher efficiencies than single-junction perovskite solar cells (PSCs) but still suffer from the unsatisfactory performance of low-bandgap (LBG) tin-lead (Sn-Pb) subcells. The inherent properties of PEDOT:PSS are crucial to high-performance Sn-Pb perovskite films and devices; however, the underlying mechanism has not been fully explored and revealed. Here, we report a facile oxalic acid treatment of PEDOT:PSS (OA-PEDOT:PSS) to precisely regulate its work function and surface morphology. OA-PEDOT:PSS shows a larger work function and an ordered reorientation and fiber-shaped film morphology with efficient hole transport pathways, leading to the formation of more ideal hole-selective contact with Sn-Pb perovskite for suppressing interfacial nonradiative recombination losses. Moreover, OA-PEDOT:PSS induces (100) preferred orientation growth of perovskite for higher-quality Sn-Pb films. Last, the OA-PEDOT:PSS-tailored LBG PSC yields an impressive efficiency of up to 22.56% (certified 21.88%), enabling 27.81% efficient all-perovskite TSC with enhanced operational stability.

Homogenizing Morphology and Composition of Methylammonium‐Free Wide‐Bandgap Perovskite for Efficient and Stable Tandem Solar Cells

AbstractA facile and eco‐friendly dimethyl sulfoxide‐mediated solution aging (DMSA) treatment is presented to control the crystallization dynamics of methylammonium (MA)‐free wide‐bandgap (WBG) perovskite films, enhancing film quality, and morphology for high‐performance tandem solar cells. The comprehensive structural, morphological, and characterization analyses reveal that the DMSA treatment significantly enhances composition and morphology homogeneity while suppressing halide segregation. Consequently, opaque, and semi‐transparent MA‐free WBG perovskite solar cells (PSCs) exhibit remarkable power conversion efficiencies (PCEs) of 18.28% and 17.61%, respectively. Notably, the unencapsulated DMSA‐treated devices maintain 95% of the initial PCE after 900 h of continuous operation at 55 °C ± 5 °C. Furthermore, stacking semi‐transparent DMSA‐treated PSCs as top cells in a 4T tandem configuration, along with silicon heterojunction (SHJ), lead–tin (Pb–Sn) alloyed PSCs, and organic photovoltaics (OPV) as bottom cells, yields impressive PCEs of 28.09%, 26.09%, and 25.28%, respectively, for the fabricated tandem cells. This innovative approach opens new avenues for enhancing the photo‐stability and photovoltaic performance of perovskite‐based tandem solar cells.

Enhancing the Efficiency and Stability of Tin-Lead Perovskite Solar Cells via Sodium Hydroxide Dedoping of PEDOT:PSS.

Tin-lead (Sn-Pb) perovskite solar cells (PSCs) have gained interest as candidates for the bottom cell of all-perovskite tandem solar cells due to their broad absorption of the solar spectrum. A notable challenge arises from the prevalent use of the hole transport layer, PEDOT:PSS, known for its inherently high doping level. This high doping level can lead to interfacial recombination, imposing a significant limitation on efficiency. Herein, NaOH is used to dedope PEDOT:PSS, with the aim of enhancing the efficiency of Sn-Pb PSCs. Secondary ion mass spectrometer profiles indicate that sodium ions diffuse into the perovskite layer, improving its crystallinity and enlarging its grains. Comprehensive evaluations, including photoluminescence and nanosecond transient absorption spectroscopy, confirm that dedoping significantly reduces interfacial recombination, resulting in an open-circuit voltage as high as 0.90V. Additionally, dedoping PEDOT:PSS leads to increased shunt resistance and high fill factor up to 0.81. As a result of these improvements, the power conversion efficiency is enhanced from 19.7% to 22.6%. Utilizing NaOH to dedope PEDOT:PSS also transitions its nature from acidic to basic, enhancing stability and exhibiting less than a 7% power conversion efficiency loss after 1176h of storage in N2 atmosphere.

Analysis and Selection of Optimal Perovskite/Silicon Tandem Configuration for Building Integrated Photovoltaics Based on Their Annual Outdoor Energy Yield Predicted by Machine Learning

Accurate estimation of annual output energy yield () for perovskite/silicon (PSK/cSi) tandem solar cells is pivotal in assessing their suitability for building‐integrated photovoltaics (BIPV). This study pioneers five machine learning models of ensembles of trees, Gaussian process regressions, regression trees, support vector machines, and artificial neural networks (ANN) to predict output power density and compute for 2T, 3T, and 4T PSK/cSi tandem configurations in Japan's outdoor conditions. Seven predictive inputs of visible‐light solar irradiance, near‐infrared‐light solar irradiance, incident solar spectrum angle, solar module temperature, perovskite thickness, perovskite bandgap, and terminal of tandem configuration (T) drive the machine learning models. These models optimize predictions using k‐fold cross‐validation and Bayesian algorithms, showcasing superior precision in prediction compared to prior models. The ANN model emerges as the best model, displaying the minimal error in predicting , used to estimate across five Japanese locations (Gifu, Naganuma, Okinoerabu, Tosu, and Tsukuba). Results from these locations in blue‐rich solar spectrum zones identify the 4T PSK/cSi tandem configuration, featuring the most outstanding mean maximal (93.63, 263.02, 153.59, and 91.75 kWh m−2 for the east, rooftop, south, and west directions), as the prime candidate for BIPV applications.

Exploring the potential of tin-based perovskite-silicon tandem solar cells through numerical analysis: A pathway to sustainable energy innovation

“Necessity is the mother of invention.” The global imperative to transition from fossil fuels to renewable energy sources, driven by the pressing issue of climate change, highlights the significance of advancing solar energy technologies. While single junction solar cells have reached a peak efficiency of approximately 31 %, the pursuit of higher efficiency has led to the exploration of tandem solar cell architectures, including perovskite-silicon and all-perovskite configurations. However, the widespread use of lead in perovskite structures raises environmental and health concerns. In response to these challenges, this study proposes a novel approach by integrating a tin-based wide bandgap absorber layer with a silicon HIT solar cell (Heterojunction with Intrinsic Layer). The investigation consists of an extensive exploration of six different carrier transport layers (CTL) for the top perovskite layer, considering variations in thickness and defect density. A comprehensive analysis of charge carrier dynamics within the device is conducted to understand the role of defect density in influencing solar cell performance parameters. Simulation results show that the overall tandem device gives an encouraging PCE of 32.12 % in 2 T configuration due to its excellent high value of current density matching 17.63 mA/cm2 and open-circuit voltage of 2.19V. We sincerely hope that our work will open new avenues in the field of Solar Photovoltaics paving the way for future innovations.

Phase-stable wide-bandgap perovskites enabled by suppressed ion migration

Wide-bandgap (>1.7 eV) perovskites suffer from severe light-induced phase segregation due to high bromine content, causing irreversible damage to devices stability. However, the strategies of suppressing photoinduced phase segregation and related mechanisms have not been fully disclosed. Here, we report a new passivation agent 4-aminotetrahydrothiopyran hydrochloride (4-ATpHCl) with multifunctional groups for the interface treatment of a 1.77-eV wide-bandgap perovskite film. 4-ATpH+ impeded halogen ion migration by anchoring on the perovskite surface, leading to the inhibition of phase segregation and thus the passivation of defects, which is ascribed to the interaction of 4-ATpH+ with perovskite and the formation of low-dimensional perovskites. Finally, the champion device achieved an efficiency of 19.32% with an open-circuit voltage (VOC) of 1.314 V and a fill factor of 83.32%. Moreover, 4-ATpHCl modified device exhibited significant improved stability as compared with control one. The target device maintained 80% of its initial efficiency after 519 h of maximum power output (MPP) tracking under 1 sun illumination, however, the control device showed a rapid decrease in efficiency after 267 h. Finally, an efficiency of 27.38% of the champion 4-terminal all-perovskite tandem solar cell was achieved by mechanically stacking this wide-bandgap top subcell with a 1.25-eV low-bandgap perovskite bottom subcell.

Tail states suppression via surface-modification of wide-bandgap perovskites for high-efficiency all-perovskite photovoltaic tandems

As an essential light-absorbing material in perovskite-based tandem solar cells, wide-bandgap (WBG) perovskite has garnered extensive attention. Nevertheless, due to severe non-radiative recombination from tail states, as well as photoinduced phase segregation and unoptimized charge transfer, WBG perovskite solar cells (PSCs) typically display significant open-circuit voltage (VOC) loss and low fill factor (FF). In this work, we report to modify the 1.68 eV WBG perovskite film upon optimized surface passivation with 1,3-propane-diammonium iodide (PDAI2). Time-resolved microwave conductivity measurement is employed to analyze the tail states, mobilities of charge carriers and the rate constants of recombination in perovskite films. The results indicate that the optimized surface modification strategy not only enhances film quality, boosts carrier transport, but also suppresses tail states and therefore diminishes non-radiative recombination, consequently elevating the VOC and FF of the device. Hence, the PDAI2-assisted WBG PSCs deliver an optimal efficiency of 21.48 %, accompanied by a VOC of 1.243 V. Furthermore, the integration of a narrow-bandgap tin–lead PSC with a semi-transparent WBG PSC results in a four-terminal perovskite/perovskite tandem solar cell, showcasing an efficiency surpassing 28 %. Our research offers a practical approach for producing efficient WBG PSCs and tandem solar cells.

Multifunctional Spacer in 2D/3D Wide‐Bandgap Perovskite for Monolithic Perovskite/Silicon Tandem Solar Cells

To maximize the power conversion efficiency (PCE) and stability of perovskite/silicon tandem solar cells (TSCs), high‐performance and stable perovskite top cells with wide‐bandgaps are required. A 2D/3D wide‐bandgap perovskite with a bandgap of 1.69 eV using 1H‐1,2,4‐triazole‐1‐carboximidamide (1‐TzFACl) as a spacer is developed. The 2D/3D wide‐bandgap perovskite shows better film quality, enhanced crystallinity, suppressed nonradiative recombination, and significantly improved phase stability. Its initial PCE (21.58%) remains above 87% after 1560 h of continuous illumination due to the insertion of Cl− in the perovskite lattice. A monolithic two‐terminal perovskite/silicon TSC achieves a PCE of 25.66% with high light stability. This work provides an ingenious strategy to restrain the phase segregation in wide‐bandgap perovskites, leading to effective and stable perovskite/silicon TSCs.

Atomically Deciphering the Phase Segregation in Mixed Halide Perovskite

AbstractMixed‐halide perovskites show promising applications in tandem solar cells owing to their adjustable bandgap. One major obstacle to their commercialization is halide phase segregation, which results in large open‐circuit voltage deficiency and J‐V hysteresis. However, the ambiguous interplay between structural origin and phase segregation often results in aimless and unspecific optimization strategies for the device's performance and stability. An atomic scale is directly figured out the abundant Ruddlesden‐Popper anti‐phase boundaries (RP‐APBs) within a CsPbIBr2 polycrystalline film and revealed that phase segregation predominantly occurs at RP‐APB‐enriched interfaces due to the defect‐mediated lattice strain. By compensating their structural lead halide, such RP‐APBs are eliminated, and the decreasing of strain can be observed, resulting in the suppression of halide phase segregation. The present work provides the deciphering to precisely regulate the perovskite atomic structure for achieving photo‐stable mixed halide wide‐bandgap perovskites of high‐efficiency tandem solar cell commercial applications.

Research Progress of Semi-Transparent Perovskite and Four-Terminal Perovskite/Silicon Tandem Solar Cells

Perovskite/silicon tandem solar cells are of great interest due to their potential for breaking the Shockley-Queisser limit of single-junction silicon solar cells. Perovskite solar cells are widely used as the top subcells in perovskite/silicon tandem solar cells due to their high efficiency and lower fabrication cost. Herein, we review the semi-transparent perovskite solar cell in terms of the mechanisms of their translucent structure, transparent electrodes, charge transport layer, and component modification. In addition, recent progress in the research and development of 4T perovskite/silicon tandem solar cells is summarized, with emphasis on the influence of perovskite structure and silicon cells on the progress of tandem solar cells. Finally, we discuss the challenges associated with 4T perovskite/silicon tandem solar cells and suggest directions for the development of perovskite/silicon commercialization.

Advancing Monolithic Perovskite/TOPCon Tandem Solar Cells by Customizing Industrial‐Level Micro‐Nano Structures

AbstractTexturing silicon solar cells with micro/nano‐structures is crucial for achieving outstanding optical performance in perovskite/silicon tandem solar cells (TSCs). However, ensuring excellent electrical properties remains a challenge due to reduced passivation quality of the bottom silicon sub‐cells and difficulties in perovskite formation on textured substrates. Here, an industrial‐level sub‐micron random pyramid (sMRP) structure on the front side of a tunnel oxide passivating contact (TOPCon) solar cell using a simple alkaline texturing process is presented, resulting in excellent optical and electrical properties. Through meticulous fabrication process tuning, uniform sMRP textures with a size of 0.6–0.8 µm are achieved, exhibiting low reflectance comparable to industrial‐level micron random pyramid (MRP) structures. Optimizing annealing temperatures of double‐sided TOPCon structures textured with front‐sided sMRP and rear‐sided MRP, yields high passivation quality, with a remarkable implied open‐circuit voltage (iVOC) of 713 mV. Furthermore, the sMRP‐textured surface facilitates the formation of a high‐quality perovskite film with larger grain sizes and fewer internal pinholes compared to the polished counterpart. Consequently, a proof‐of‐concept p‐i‐n typed perovskite/TOPCon TSC featuring sMRP textures obtains an outstanding efficiency of 28.67%, providing a promising approach for the commercial production of high‐efficiency perovskite/TOPCon TSCs.

Design of Broadband and Wide-angle HLHL Antireflective Coatings for Triple Junction Solar Cells

Design of Broadband and Wide-angle HLHL Antireflective Coatings for Triple Junction Solar Cells

Surface Crystallization Enhancement and Defect Passivation for Efficiency and Stability Enhancement of Inverted Wide-Bandgap Perovskite Solar Cells.

Wide-bandgap (WBG) inverted perovskite solar cells (PSCs) are used as the top cell for tandem solar cells, which is an effective way to outperform the Shockley-Queisser limit. However, the low efficiency and poor phase stability still seriously restrict the application of WBG inverted PSCs. Here, the surface of the WBG perovskite film was passivated by the synthesized 1,2,4-tris(3-thienyl)benzene (THB). The THB size well matches with the halogen ion vacancy on the perovskite surface, and the S atom in THB can strongly interact with Pb2+ on the surface of the WBG perovskite film to the greatest extent, which effectively passivates surface defects and suppresses the recombination of carriers caused by these defects. At the same time, the S atom in THB occupied the migration site of the halogen ions, which inhibits the migration of halogen ions. Due to the strong conjugation effect and stability of THB, it can be locked on the surface of perovskite to increase the lattice strength and inhibit the segregation of photoinduced halide, thus improving the performance and operational stability of PSCs. The THB-modified WBG (Eg = 1.71 eV) PSC achieves a maximum power conversion efficiency of 20.75%, and its 99.0% is retained after 1512 h at a relative humidity of 10-25%. Under the irradiation of 1000 lx LED light, the indoor power conversion efficiency of the THB-modified WBG PSC reaches 34.15%.

Sustainable Manufacturing of Perovskite-CIGS Tandem Solar Cells through Lamination with Metal-Free Transparent Conductive Adhesives

Sustainable Manufacturing of Perovskite-CIGS Tandem Solar Cells through Lamination with Metal-Free Transparent Conductive Adhesives

Performance investigation of MAPbI3/MASnI3 based all-perovskite tandem solar cell using SCAPS simulation

Due to the complexity of the fabrication process of tandem solar cells, perovskite materials provide a cost-effective and simpler fabrication solution. In this work, MAPbI3/MASnI3 Perovskite-based Tandem solar cell has been explored numerically by using SCAPS-1D. Methylammonium Lead Iodide (CH3NH3PbI3 or MAPbI3) and Methylammonium Tin Iodide (CH3NH3SnI3 or MASnI3) have been considered as wide bandgap (WBG) and narrow bandgap (NBG) absorber material for the top cell and bottom cell, respectively. WBG top cell and NBG bottom cell are both investigated through the change in the depth of perovskite materials at the current matching conditions at the illumination of Standard AM 1.5 spectrum. The all-perovskite MAPbI3/MASnI3 tandem solar cell with copper (I) oxide (Cu2O) hole transport layer has achieved excellent performance with a maximum power conversion efficiency (PCE) of 32.74% with V oc of 1.68 V, J sc of 24.6 mA cm−2, and fill factor (FF) of 79.39%, respectively.

Investigation of the Performance of a Sb2S3-Based Solar Cell with a Hybrid Electron Transport Layer (h-ETL): A Simulation Approach Using SCAPS-1D Software

In order to reduce current leakage and improve electron transfer in solar cells, charge transport layers (CTL), mainly hybrid electron transport layers (h-ETL), are considered as a solution. In this research contribution, computational analysis using SCAPS-1D software is performed to explore the output photovoltaic parameters of a Sb2S3-based solar cell with h-ETL. No theoretical works on this configuration have been previously reported. The main objectives of the present work are to propose a h-ETL with good band alignment with the Sb2S3 absorber, high transparency, and Cd free; to mitigate the instability and cost issues associated with using Spiro-OMeTAD HTL; and to optimize the solar cell. Thus, we calibrated the J-V characteristics and electrical parameters of the FTO/(ZnO/TiO2)/Sb2S3/Spiro-OMeTAD/Au solar cell by numerical simulation and compared them with those of the experiment. Subsequently, our simulations show that to replace the TiO2 ETL used in the experiment and to form the h-ETL with ZnO, IGZO is found to be a good candidate. It has better band alignment with the Sb2S3 absorber than TiO2 ETL, which reduces the trap states at the ETL/Sb2S3 interface; it has high transparency due to its wide bandgap; and an intense electric field is generated at the IGZO/Sb2S3 interface, which reduces the recombination phenomenon at this interface. MoO3, MASnBr3, Cu2O, CuI, and CuSCN HTL were also tested to replace the Spiro-OMeTAD HTL. Simulation results show that the cell with MoO3 HTL achieves higher performance due to its high hole mobility and high quantum efficiency in the visible region; it also allows the solar cell to have better thermal stability (TC=−0.32%/K) than the cell with Spiro-OMeTAD HTL (TC=−0.53%/K). The parameters that could improve the solar cell efficiency (η) obtained after these substitutions were also optimized. In particular, the parameters of the Sb2S3 absorber layer (thickness, defect density, and doping), ETL and HTL layer thicknesses, h-ETL/Sb2S3 interface defect density, and series and shunt resistances have been optimized. Finally, by combining high performance and thermal stability, the results show that the thermal stability of the solar cell depends on the back contact type; thus, nickel (Ni) was found to combine high performance and better thermal stability among the back contacts investigated. After these improvements, the efficiency of the Sb2S3-based solar cell increased from 5.08% (JSC=16.19 mA/cm2, VOC=0.56 V, and FF=55.40%) to 15.43% (JSC=18.51 mA/cm2, VOC=1.11 V, and FF=74.76%). This study proposes an approach to optimize the Sb2S3 upper subcell for tandem solar cells.