Structure Perovskite Solar Cells Research Articles

Highly transparent and conductive Ga-doped InWO multi-component electrodes for Perovskite photovoltaics

Wide-bandgap Ga-doped InWO (GIWO) transparent conductive electrodes (TCE) were fabricated by co-sputtering IWO and Ga2O3, followed by rapid thermal annealing (RTA), with the effects of the Ga dopant content on the electrical, optical, structural, and morphological properties of the GIWO multi-component electrodes investigated to optimize the GIWO electrode. According to the figure of merit (FOM), the GIWO film with a Ga content of 2.1 at% exhibited a low sheet resistance of 9.9 Ohm/square and high transmittance of 91.71 % at a wavelength of 550 nm. The presence of a high Lewis acid strength (LAS) dopant of Ga (1.16) and W (3.15) led to an increase in the carrier mobility of GIWO and transmittance in the near infrared wavelength region. In addition, the strongly preferred (222) and (400) orientations of the GIWO grains increase the carrier mobility and improve the surface morphology of the GIWO electrodes. The successful operation and superior performance of the planar p-i-n structured perovskite solar cells (PSC) fabricated on GIWO electrodes indicate the feasibility of GIWO as a substitute for conventional Sn-doped In2O3 electrodes. The highest-performing PSC with GIWO electrodes exhibited reliable hysteresis with an efficiency difference of less than 1 % depending on the scan direction under standard AM1.5 G conditions.

Design and optimization of Cs2SnI6 based inorganic perovskite solar cell model: numerical simulation

To overcome the drawbacks of high lead toxicity and poor corrosion resistance of lead-based perovskite solar cells (PSCs), and to compensate for the poor air stability of Sn2+ compound-based perovskite, Cs2SnI6 (Sn4+ compound) is selected as the absorber for the PSC in this study. Using FTO/ETL/Cs2SnI6/HTL/Au as the model, the high-performance non-toxic inorganic PSC structure is explored through theoretical simulation and calculation by SCAPS-1D. The conduction band offsets (CBO) and valence band offsets (VBO) of commonly used electron transport layer materials (ETMs), hole transport layer materials (HTMs), and Cs2SnI6 are calculated based on electron affinity potential (χ) and bandgap (E g ). Then, by analyzing the pn junction composed of ETL and HTL and the bandgap structure at the n-i, i-p interfaces, the most matching n-i-p planar heterojunction model, FTO/IGZO/Cs2SnI6/Cu2BaSnS4/Au, was selected. Finally, by analyzing and adjusting the material thickness, defect density of each layer, operation temperature, the optimal performance of PSC was determined to be 30.39% power conversion efficiency (PCE), 1.27 V open circuit voltage (V oc ), 28.46 mA cm−2 short circuit current (J sc ), and 84.02% fill factor (FF). A new and more efficient PSC is proposed in this study, providing some terrific clues for finding high-quality alternatives to lead-based PSCs.

Perovskite solar cells: Fundamental aspects, stability challenges, and future prospects

Interest in perovskite solar cell (PSC) research is increasing because PSC has a remarkable power conversion efficiency (PCE), which has notably risen to 28.3 %. However, commercialization of PSCs faces a significant obstacle due to their stability issues. This review article primarily focuses on several key aspects of PSCs, including different types of solar cells, their construction and operational mechanisms, efficiency, and overall stability. It explains the structure and functioning of PSCs, covering materials and components used for absorber layer, electron-transport layer, hole-transport layer, and electrodes. This review emphasized stability challenges associated with PSCs and discussed various factors and issues contributing to the degradation of these solar cells over time. It then provided a concise overview of different strategies and ongoing efforts taken to enhance the stability of PSCs. It also summarized various approaches used to improve their durability. In summary, this article offers a comprehensive exploration of PSCs, encompassing their construction, operation, improvement in efficiency, and obstacles related to their long-term stability. Furthermore, it addresses factors influencing PSC stability and outlines future challenges, focusing on prolonging their lifespan and enhancing stability for broader applications. Finally, this article has tackled various possible solutions to address the challenges encountered by the PSCs.

Optimization of the ETL titanium dioxide layer for inorganic perovskite solar cells

Titanium dioxide layers are the most popular electron transport layer (ETL) in perovskite solar cells. However most studies focuses on mesoporous structure and application with organic–inorganic hybrid perovskite. In this study, the topic of ETL in planar structure of inorganic CsPbBr3 perovskite solar cells was tackled, the presented approach will reduce production costs and improve cell stability, which is the greatest drawback of perovskite cells especially organic–inorganic perovskite. The potential application of these technology are greenhouses and building integrated PV sector. Here, the two TiO2 precursors titanium(IV) ethoxide in ethanol and titanium(IV) bis(acetylacetonate) diisopropoxide (Tiacac) were investigated, optimized and compared. TiO2 layers were deposited on high roughness FTO, without the use of a mesoporous layer, by spin coating method. The correlation between stock solution concentration and thickness of manufactured layers was tracked for both precursors as well as their difference in morphology of the final films and other properties. In particular, conformality and optical properties are better for Tiacac. Slightly lower refractive index of Tiacac-based titania reduced the reflective losses from 7.3 to 6.9% effectively. The obtained layers were used for inorganic solar cells of CsPbBr3 perovskite to finally settle the issue of optimal thickness and precursor. It is interesting that despite the supremacy in investigated properties of commonly used of the precursor Tiacac, the results of the cells pointed to the Tieth. The efficiency of the champion cell is 6.08% for Tieth, while 5.62% is noted for Tiacac. Trying to figure out this riddle, we shed a new light on the phenomena going on the ETL/inorganic perovskite interface investigating nanoroughness.

SCAPS-1D Simulation for Device Optimization to Improve Efficiency in Lead-Free CsSnI3 Perovskite Solar Cells

In this study, a novel systematic analysis was conducted to explore the impact of various parameters, including acceptor density (NA), individual layer thickness, defect density, interface defect density, and the metal electrode work function, on efficiency within the FTO/ZnO/CsSnI3/NiOx/Au perovskite solar cell structure through the SCAPS-1D (Solar Cell Capacitance Simulator in 1 Dimension) simulation. ZnO served as the electron transport layer (ETL), CsSnI3 as the perovskite absorption layer (PAL), and NiOx as the hole transport layer (HTL), all contributing to the optimization of device performance. To achieve the optimal power conversion efficiency (PCE), we determined the ideal PAL acceptor density (NA) to be 2 × 1019 cm−3 and the optimal thicknesses to be 20 nm for the ETL (ZnO), 700 nm for the PAL (CsSnI3), and 10 nm for the HTL (NiOx), with the metal electrode remaining as Au. As a result of the optimization process, efficiency increased from 11.89% to 23.84%. These results are expected to contribute to the performance enhancement of eco-friendly, lead-free inorganic hybrid solar cells with Sn-based perovskite as the PAL.

Investigation of HTL-free perovskite solar cell under LED illumination: interplay between energy bandgap and absorber optimization

In this paper, we introduce an efficient perovskite solar cell (PSC) designed for indoor applications, which does not incorporate a hole transport layer (HTL). The perovskite material studied in this work is MAPbI3-xClx, whose bandgap energy can be adjusted to match the spectrum of white LEDs. While the removal of the HTL initially leads to a decline in cell performance, a subsequent enhancement is achieved in performance when the work function of the rear contact is increased. This improvement can be attributed to the increased electric field at the back contact interface. The performance of the HTL-free PSC is further optimized by adjusting various technological and physical factors of the perovskite absorber. These parameters include thickness, bulk defects, doping level, and energy gap of the perovskite material. Our results demonstrate that the HTL-free PSC structure exhibits superior performance metrics under a white LED environment at 1000 lux and a color temperature of 2700 K. In this context, a power conversion efficiency (PCE) above 34% can be obtained upon proper optimization procedures. Further, the interplay between the energy gap (E g ) of the absorber and the optimization procedures is investigated, highlighting its importance in the context of HTL-free designs for indoor applications. Practical recommendations stemming from this study include an emphasis on optimization for HTL-free cells and caution against applying ideal E g ranges to non-optimized configurations.

Spin-coated high mobility MoO3 thin film for designing highly efficient lead-free perovskite solar cells

Among the thin film-photovoltaics, perovskite solar cells (PSCs) are one of the most developing topics of research in recent times. Research records reveal that around 26 % efficiency in PSCs has already been achieved so far. However, the commercialization of those PSCs is hindered due to the toxicity of lead (Pb), and the instability of organic cations as well as structural volatility. Several inorganic materials including inorganic hole transport layer (HTL) have recently been proposed and developed to reduce the organic part in the device structure. We fabricate MoO3 thin film materials and conduct a detailed study to realize the potential of MoO3 as a unique HTL for application in PSCs. The synthesis of MoO3 thin film includes several characterization techniques e.g. XRD, FESEM, EDX, UV–Vis, and Hall Effect measurement. We design a MoO3 thin film-based, lead-free PSC structure of FTO/MoO3/PTAA/(FA)2BiCuI6/ZnO/Ag and perform numerical analysis using the SCAPS-1D simulation tool. In the device simulation process, we use the experimentally obtained optoelectrical properties of the MoO3 film and achieve a maximum efficiency of around 22.28 % in a contained lead-free PSC.

Numerical analysis of ultra-thin MASnI3 based perovskite solar cell by SCAPS-1D

Future solar cells are perovskite solar cells (PSC). Silicon based solar cells offer an unlimited source of clean energy. Even if perovskite PCE is currently not at its optimum, it has shown great potential for improvement. Numerical analysis of PSC is now more convenient using different simulation software which is a great way to experiment on PSC. In this study, a unique structure of PSC has been proposed, its key parameters like acceptor density, perovskite defect density, interface defect density, and thickness has been investigated to find out their impact on device performance. After optimization a high power conversion efficiency (PCE) 30.57%, open circuit voltage of 1.02 V, short circuit current of 34.68 (mA/Cm2 ) and fill factor 86.21% respectively was obtained.

Surface crack effect on frequency and vibration mode switching of solar-powered aerospace structures

In the engineering design of modern wing panels and their optimal control system, the first step is to find and predict their dynamic characteristics. These characteristics are dependent on material properties, panel geometry, and boundary conditions. In addition, possible fracture existence, imperfections and environmental conditions may unpredictably change the frequency and modes shape of the panel and then the parameters of a control system. In the present paper, the effect of surface fracture depth and orientation on frequency and vibration mode switching of perovskite solar cells-based aircraft wing panels is investigated for the first time. The PSC (perovskite solar cell) panel is made of a polymer substrate reinforced with even-distributed graphene platelets (GPLs) and thin solar layers to enhance the overall electromechanical performance of the whole structure. Equations of motion of the panel are obtained by the Hamilton approach based on the properties of Reddy's third-order shear deformation theory and linear components of the Green-Lagrange strain tensor. The novel aspect is a line-spring model of surface crack by Cartmell et al. adapted to the model of the PSC panel under consideration. The discretization of the established equations of motion for the cracked panel is carried out by the element-free IMLS-Ritz method with mesh-free features. Validation of the obtained solutions is carried out by comparisons with results from previous studies for cracked laminated plates.First, material and geometric properties effect on vibration characteristics of the PSC structure was investigated. Next, partial surface crack depth and orientation angle are examined to show changes in frequency and vibration modes shape of the panel. It is shown, that there is a mode swapping between the second and third modes when transitioning from an intact panel to a cracked one. As the crack length increases, higher-order mode variations become more noticeable, potentially leading to their swapping or the excitation of new ones. Additionally, the findings demonstrate that the surface crack orientation angle significantly impacts the higher-order modes of the panel. When the orientation angle is 90°, the first six modes align with those of the intact plate. Mode shapes and frequency shifts are significant for crack orientation angles between 0° and 90°.

Performance optimization study of lead-free CsSnGeI3 based perovskite solar cell heterostructure with different inorganic electron transport layers: A numerical simulation approach

Perovskite solar cells (PSCs) are considered to be one of the most prominent candidates for its commercialization. The meteoric properties of the PSC have always astounded the researchers. Thus, in this perspective, the germanium-based PSCs are able to increase a sense of curiosity among photovoltaic (PV) researchers due to its superior stability and efficiency. In the present work, different combinations of the lead-free and non-toxic inorganic caesium tin-germanium (CsSnGeI3) based PSC structures have been studied using various electron transport layers (ETLs) (SnS2, TiO2, WS2, MoTe2 and ZnSe) and Mg–CuCrO2 as a hole transport layer due to its meteoric properties. For each ETL, the impact of material parameters including the thickness of the various layers, absorber acceptor density, donor density, absorber defect density, absorber radiative recombination and interfacial defect density are examined to study the cell performance (such as Voc, Jsc, FF, and PCE). Moreover, the role of operating temperature, shunt resistance and series resistance in analysing the cell performance has also been checked towards its practical applicability. The results show ZnSe as the best ETL in comparison to other inorganic ETLs for CsSnGeI3 based absorber with Mg–CuCrO2 as an HTL, used in this work resulting in a good cell performance with a power conversion efficiency (PCE) of 33.24%, Voc ∼ 1.36 V, Jsc ∼ 28.02 mA/cm2 and fill factor (FF) ∼ 86.79%. The proposed simulation work may pave the way for further design and optimization of Sn-based PSCs towards practical applications.

High-Efficiency and Ultra-Stable Cesium-Bismuth-Based Lead-free Perovskite Solar Cells without Modification.

Perovskite solar cells (PSCs) have become a new photovoltaic technology with great commercial potential because of their excellent photovoltaic performance. However, the toxicity and poor environmental stability of Pb in Pb-based perovskites limit its large-scale application. Exploring alternatives to Pb is an available approach to develop environmentally friendly PSCs. As an adjacent element of Pb, Bi shows many similar physical and chemical properties; therefore, it is commonly applied for B site substitution in Pb-based PSCs. CsBiSCl2, a new Pb-free perovskite system, was synthesized for the first time as a light absorber. By preparing DMABiS2 as an intermediate, Cs-Bi-based CsBiSCl2 perovskite films with a band gap over 2.012 eV were prepared by introducing CsCl, and the optimal annealing temperature, time, and stoichiometric ratio of the film were explored in this work. The conventional structure of CsBiSCl2 PSCs achieved a power conversion efficiency (PCE) of 10.38%, and the efficiency declined by only 3% after aging in air for 150 days, showing excellent stability, which is one of the most stable devices in inorganic PSCs. This work opens up a new road for the future development of environmentally friendly and commercially stable lead-free PSCs.

All-Inorganic Perovskite Solar Cells: Defect Regulation and Emerging Applications in Extreme Environments.

All-inorganic perovskite solar cells (PSCs), such as CsPbX3, have garnered considerable attention recently, as they exhibit superior thermodynamic and optoelectronic stabilities compared to the organic-inorganic hybrid PSCs. However, the power conversion efficiency (PCE) of CsPbX3 PSCs is generally lower than that of organic-inorganic hybrid PSCs, as they contain higher defect densities at the interface and within the perovskite light-absorbing layers, resulting in higher non-radiative recombination and voltage loss. Consequently, defect regulation has been adopted as an important strategy to improve device performance and stability. This review aims to comprehensively summarize recent progresses on the defect regulation in CsPbX3 PSCs, as well as their cutting-edge applications in extreme scenarios. The underlying fundamental mechanisms leading to the defect formation in the crystal structure of CsPbX3 PSCs are firstly discussed, and an overview of literature-adopted defect regulation strategies in the context of interface, internal, and surface engineering is provided. Cutting-edge applications of CsPbX3 PSCs in extreme environments such as outer space and underwater situations are highlighted. Finally, a summary and outlook are presented on future directions for achieving higher efficiencies and superior stability in CsPbX3 PSCs.

Facilitating Electron Transport in Perovskite Solar Cells Through Tailored SnO2 Film Composition

The ratio of Sn2+ to Sn4+ plays an essential role in influencing the characteristics of SnO2 film, which is commonly used in the normal structure of perovskite solar cells (PSCs). It is identified that different sequences of addition lead to varying concentrations of Sn2+ and Sn4+ within the SnO2 film. Through this strategic approach, an enhanced SnO2 film with improved electron transport capabilities, a smoother surface texture, and more suitable energy levels are successfully engineered. Consequently, the efficiency of PSCs has seen a notable increase from 22.58% for the control device to 24.16% for the target PSC. Furthermore, PSCs utilizing the optimized SnO2 have demonstrated superior long‐term environmental stability when compared to the control devices. Specifically, PSCs incorporating optimized SnO2 expose to approximately 30% humidity in ambient air for 41 days without encapsulation retain 87% of their initial efficiency. In contrast, the control devices under the same conditions only maintain 77% of their original value.

Optical properties study of a perovskite solar cell film stack by spectroscopic ellipsometry and spectrophotometry

Spectroscopic ellipsometry is a reproducible and non-invasive characterization technique that allows the evaluation of multilayered structures. However, it is an indirect technique and requires the use of well-calibrated models to correctly analyze the materials. In this work, we report a multilayer modeling approach to investigate the optical properties of the three layers of interest typically employed on an inverted perovskite solar cells structure, namely, indium-tin-oxide (ITO) as a transparent anode, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a hole transport layer, and methylammonium lead iodide (MAPbI3) as the perovskite layer. The parameterized optical constants based on oscillator models were simultaneously fitted to ellipsometry and intensity-transmission data and validated with ultraviolet–visible (UV–Vis) spectroscopy and profilometry. We propose this multilayer modeling approach as a method to be employed throughout the different stages of the fabrication process to study the distinct mechanisms that impact the final performance of a photovoltaic device.

Thermal modeling of perovskite solar cells: Electron and hole transfer layers effects

The thermal behavior of perovskite solar cells (PSCs) can significantly affect their performance, and its investigation leads to a deep understanding of PSCs optimization. In this paper, the electrical and thermal behavior of a PSC is studied. To this end, the optical generation rate is calculated for the standard AM 1.5 solar spectrum and then is applied to calculate the current-voltage characteristics. Examining the efficiency (considering the recombination) for different materials of the electron and hole transfer layers (ETM, HTM, respectively), a structure with better merits is selected. The results revealed that Spiro-OMeTAD as the HTM layer leads to better results than the inorganic one. Hence, the Spiro-OMeTAD-based PSC structures were selected for the thermal modeling section. In the final step, considering the heat generated due to losses (resulting from resistive heating and non-radiative recombination), the thermal behavior of devices is surveyed. The structures with geometrical dimensions of a practical PSC (deposited on a glass substrate with a SiO2 passivation layer) show operating temperatures between 73 °C to 76°C and 80°C to 84.5°C for ZnO and TiO2 as ETMs, respectively. The high heat generated in the perovskite layer can accelerate its undesirable chemical reactions. Surveying the temperature distribution of PSCs can pave the way to study its effects on ion migration and the corrosion of contacts, which are the main drawbacks of such low-cost energy harvesters.

DFT Investigation of Structural Stability, Optical Properties, and PCE for All-Inorganic Csx(Pb/Sn)yXz Halide Perovskites.

Employing all-inorganic perovskites as light harvesters has recently drawn increasing attention owing to the strong-bonded inorganic components in the crystal. To achieve the systematic and comprehensive understanding for the structures and properties of Csx(Pb/Sn)yXz (X = F, Cl, Br, I) perovskites, this work provides the comparison details about crystal structures, optical properties, electronic structures and power conversion efficiency (PCE) of 18 perovskites. The suitable band gaps are detected in CsSnCl3-Pm3̅m (0.96 eV), γ-CsPbI3-Pnma (1.75 eV), and CsPbBr3-Pm3̅m (1.78 eV), facilitating the conversion from absorbing photon energy to generating hole-electron pairs. γ-CsPbI3-Pnma and CsSnI3-P4/mbm show superior visible-absorption performance depending on their higher absorption coefficient (α); meanwhile, strong peaks can be observed in the real part (Re) of photoconductivity of CsPbBr3-Pbnm, γ-CsPbI3-Pnma, and CsSnI3-P4/mbm in the visible-light range, implying their better photoelectric conversion abilities. The perovskite/tungsten disulfide (WS2) heterojunctions are constructed to calculate the PCE. Although just the PCE result (14.43%) of CsSnI3-Pnma/WS2 is reluctantly competitive, the predictions of PCEs indicate that the PCE of PSCs (perovskite solar cells) can be improved by not only regulating the perovskite to upgrade its own performance but also designing the PSC structure reasonably including the selection of appropriate ETL/HTL (electron/hole transport layer), etc.

Cu2(Thiourea)Br2 Complex as a Multifunctional Interfacial Layer for Reproducible PTAA‐Based p–i–n Perovskite Solar Cells

Poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine (PTAA) is one of the most efficient hole transport materials for p–i–n structured perovskite solar cells (PSCs). However, the hydrophobicity of PTAA causes wettability problems and is thereby associated with low yield and poor reproducibility. Herein, a new strategy for improving the perovskite precursor wettability on PTAA is developed. A Cu2(Thiourea)Br2 complex interfacial layer is introduced on the PTAA, improving the coverage of perovskite precursors and thereby the perovskite film. Partially dissolved Cu2(Thiourea)Br2 in the perovskite absorber further enhances band alignment and carrier extraction between layers. With the addition of Cu2(Thiourea)Br2 layer on nondoped PTAA, PSCs in p–i–n structure with a bandgap of 1.63 eV have achieved over 21% efficiency both on 0.1 and 1.0 cm2 sized devices with a significantly improved yield and reproducibility. Unencapsulated devices retain 100% of their initial efficiency after 2000 h at 65 °C.

Investigations on performance parameters of graphene interfacial layer modified FASnI3: Zn-based lead-free perovskite solar cells

The emerging and extensively approved solar technology be certainly of perovskites, by virtue of their exceptional contributions. However, their massive production senses on the remaining hurdles that are to be crossed before making them commercially diligent. This investigation highlights the measures to be taken to implement a lead free, highly stable perovskite solar cells (PSCs). The use of Zn-doped, Sn-based as perovskite (PVT) absorber layer together with graphene passivation layer at PVT/ hole transport layer (HTL) interface resulted in effective implementation of this phenomenon. In this research, a systematic numerical validation of PSC structure with FTO/ZnOS/FASnI3:Zn/Graphene/Cu2O/Au. The results revealed that graphene interfacial layer with adequate bandgap and electron affinity offer appreciable efficiency through proper band alignment and suppressed carrier recombination. Moreover, the recommended device contributes exceptional performance parameters: (Jsc, Voc, FF, and η) of (20.13 mA/cm2, 1.207 V, 87.13%, and 21.17%) for minimum PVT defect density of 1 × 1013 cm−3.

Enhancing Surface Modification and Carrier Extraction in Inverted Perovskite Solar Cells via Self-Assembled Monolayers.

Perovskite solar cells (PSCs) have been significantly improved by utilizing an inorganic hole-transporting layer (HTL), such as nickel oxide. Despite the promising properties, there are still limitations due to defects. Recently, research on self-assembled monolayers (SAMs) is being actively conducted, which shows promise in reducing defects and enhancing device performance. In this study, we successfully engineered a p-i-n perovskite solar cell structure utilizing HC-A1 and HC-A4 molecules. These SAM molecules were found to enhance the grain morphology and uniformity of the perovskite film, which are critical factors in determining optical properties and device performance. Notably, HC-A4 demonstrated superior performance due to its distinct hydrophilic properties with a contact angle of 50.3°, attributable to its unique functional groups. Overall, the HC-A4-applied film exhibited efficient carrier extraction properties, attaining a carrier lifetime of 117.33 ns. Furthermore, HC-A4 contributed to superior device performance, achieving the highest device efficiency of 20% and demonstrating outstanding thermal stability over 300 h.

Self-Assembled Monolayer-Based Hole-Transporting Materials for Perovskite Solar Cells.

Ever since self-assembled monolayers (SAMs) were adopted as hole-transporting layers (HTL) for perovskite solar cells (PSCs), numerous SAMs for HTL have been synthesized and reported. SAMs offer several unique advantages including relatively simple synthesis, straightforward molecular engineering, effective surface modification using small amounts of molecules, and suitability for large-area device fabrication. In this review, we discuss recent developments of SAM-based hole-transporting materials (HTMs) for PSCs. Notably, in this article, SAM-based HTMs have been categorized by similarity of synthesis to provide general information for building a SAM structure. SAMs are composed of head, linker, and anchoring groups, and the selection of anchoring groups is key to design the synthetic procedure of SAM-based HTMs. In addition, the working mechanism of SAM-based HTMs has been visualized and explained to provide inspiration for finding new head and anchoring groups that have not yet been explored. Furthermore, both photovoltaic properties and device stabilities have been discussed and summarized, expanding reader's understanding of the relationship between the structure and performance of SAMs-based PSCs.