Perovskite Thickness Research Articles

Thick film high-performance carbon-based CsPbIBr2 perovskite solar cells vis nano-perovskite modified hot casting method

All-inorganic carbon-based CsPbIBr2 perovskite solar cells (PSCs) have attracted attention due to their more balanced performance and stability. The performance of the PSCs is highly dependent on the quality of the absorber films. Unfortunately, most high-performance films are prepared in a glove box and conventional preparation methods often produce perovskite films within 400 nm of thickness, which is detrimental to large area device fabrication and limits their commercial application. Here we had demonstrated a short chain ligands nano-CsPbIBr2 particles modified hot-casting method to deposit a perovskite film with thickness up to 800 nm. It was carried out by spin-coating a hot CsPbIBr2 precursor solution onto nano-CsPbIBr2 particles film on an electron transport layer (ETL), and then depositing nano-CsPbIBr2 particles on the precursor film again before annealing. The nano-CsPbIBr2 particles on the ETL promotes precursor solution crystallization and increased film thickness, and the nano-CsPbIBr2 particles on the precursor film promoted grain growth and reduced defects due to compositional deviations from stoichiometric ratios. The power conversion efficiency (PCE) of the PSCs fabricated by this method is up to 10.66 %. The unencapsulated PSCs still retain more than 85 % of the initial PCE when stored at ambient atmosphere (RH 50–60 %) for 10 days.

Design of a p-i-n type inverted perovskite solar cell using SiOx as down-conversion material to improve PCE: Simulation and optimization in SCAPS-1D

In this research work, an inverted p-i-n type perovskite solar cell: ITO/PEDOT: PSS/CH3NH3PbI3/PCBM/Au has been simulated and optimized in SCAPS-1D. The optimized parameters in SCAPS-1D that improved solar performance were: perovskite thickness, the total defect density of perovskite, the total defect density of interfaces, series and shunt resistances, and device operating temperature. As a result, the efficiency (PCE) increased to 18.33%. Subsequently, when the silicon-rich oxide (SiOx) material was implemented in the simulation as downconversion energy material on the outside of the cell, a power conversion efficiency (PCE) of 23.7% was obtained. The SiOX film obtained experimentally by sputtering obtained good photoluminescence, absorption coefficient, band gap, and transmittance characteristics before and after thermal annealing. These characteristics have been considered for the proposed device. It is indicated that the inverted perovskite solar cell of type pi-n: SiOx/ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Au has better J-V output values and EQ quantum efficiency than the perovskite solar cell without SiOx.

Enhanced absorption in perovskite solar cells byincorporating gold triangle nanostructures.

Perovskite has emerged as an outstanding light-absorbing material, leading to significant advancements in solar cell efficiency. Further improvements can be made by restructuring the internal optical properties of perovskite. In this study, we investigate the impact of gold triangle nanostructures on perovskite absorption rates, and we explore the optimization of surface plasmon resonance to enhance its solar absorption efficiency. Our numerical simulations revealed that stacking gold triangle nanostructures in the perovskite film resulted in a significant increase in its absorption rate. Finally, comparative testing showed that the solar spectral absorption rate of a 200nm thick perovskite film increased by 41.5%.

Design and efficiency enhancing of a new perovskite solar cell through a finite element model: A 3D computational study

With considerable advancements in perovskite materials, there is a growing need for computational models to design and analyze perovskite solar cells (PSCs) before performing experiments. Hence, in this work, a combined 3D optical–electrical model based on the finite element (FE) method is reported to fully characterize a designed structure of PSC. The endeavor behind this work is to use the developed FE model to obtain enhanced insights into the new PSC performance when using two perovskite materials as absorber layers. Firstly, since the mesh elements size significantly affects the convergence of a FE model, the mesh size was validated by reproducing previous experimental data. Results from the developed FE model were also compared to those of the Solar Cell Capacitance Simulator (SCAPS-1D) software in conjunction with the experimental data. Secondly, the developed FE model was performed to study the impact of using the eco-friendly Cs2AgGaBr6 double halide perovskite material as a second absorber layer in the new PSC structure. Thirdly, the influence of different parameters, such as the perovskite thickness, order of materials, and defect density, was thoroughly investigated using the developed FE model. Thus, we managed to predict an increase of the power conversion efficiency to 27.56%, which will require experimentation validation. Finally, the effect of several periodically corrugated back layers and various reflective metals was studied. The exploitation of the developed FE model would undoubtedly be fruitful as it used to fill the gap between the important number of the perovskite materials proposed in the literature on one side, and the lack of 3D computational model allowing the design and efficiency predicting of PSC prior to the experiment on the other side.

Ray Tracing of Perovskite Thin Films for Solar Windows

In this work, OPAL 2 is used to perform ray tracing simulation on perovskite thin films based on methylammonium lead triiodide (CH3NH3PbI3) and methylammonium lead tribromide (CH3NH3PbBr3) for solar windows. The thicknesses of both perovskite materials are varied between 100 nm and 500 nm. The ray tracing is carried out within 300-1000 nm wavelength region with AM1.5G solar spectrum as the illumination source. Perovskite solar cells based on CH3NH3PbI3 demonstrate absorption edge up to wavelength of 800 nm. The short-circuit current density (Jsc) improves from 11.71 mA/cm2 to 21.07 mA/cm2 due to the increased perovskite thickness from 100 nm to 500 nm. On the contrary, the average visible transmission (AVT) drops from 45% to 13%. For perovskite solar cells based on CH3NH3PbBr3, the absorption edge is shifted to wavelength of 550 nm due to the increased band gap. The Jsc increases from 3.49 mA/cm2 to 7.25 mA/cm2 when the thickness is increased from 100 nm to 500 nm. However, the AVT drops from 74% to 59%. The findings from this work show that a trade-off is required when maximizing the Jsc of the solar cells while maintaining reasonable transparencies through the solar windows.

Light absorption enhancement of perovskite solar cells by a modified anti-reflection layer with corrugated void-like nanostructure using finite difference time domain methods

Perovskite solar cells (PSC) have become a growing research interest due to their flexibility, attractive properties, and low production cost. However, the thin-film structure of PSC often results in a not fully absorbed incident light by the active layer, which is crucial to determine PSC efficiency. Thus, the fabrication of an active layer with unique nanostructures is often used to enhance light absorption and general PSC efficiency. Using the theoretical simulation based-on Finite-Difference Time-Domain (FDTD) technique, this work demonstrates the successful improvement of light absorption by embedding corrugated void-like structure and perovskite thickness modification. The investigation of a corrugated void-type anti-reflection layer effect on light absorption is done by modifying the radius (r) and lattice constant (a) to obtain the optimum geometry. In addition, the MAPbI3 perovskite layer thickness is also adjusted to examine the optimum light absorption within the visible length to near-infrared. The theoretical calculations show that the optimum r = 692 nm and a = 776 nm. Meanwhile, the optimum absorber layer thickness is 750 nm. Compared to flat PSC, our proposed PSC absorbed more light, especially in the near-infrared region. Our result shows demonstrates the successful enhancement of light absorption by embedding corrugated void-like structure and modifying the perovskite thickness using a theoretical simulation based on the FDTD technique.

Lead-Free FACsSnI3 Based Perovskite Solar Cell: Designing Hole and Electron Transport Layer.

In recent years, lead-based perovskites solar cells have demonstrated excellent power-conversion efficiency. Despite their remarkable progress, the commercialization of lead-based perovskites is hampered by lead toxicity concerns. The recently discovered non-toxic FACsSnI3 perovskite has the potential to replace lead-based perovskites in solar cell applications. Since the perovskite material FACsSnI3 (FA0.85Cs0.15SnI3) is relatively new, there is a lack of information, particularly regarding the design features required for electron and hole-transport layers for efficient photovoltaic responses. The important variables, such as electron affinity, energy band gap, film thickness, and doping density of both electron and hole-transport layers, were simulated and modeled separately and iteratively in this study to achieve the most efficient photovoltaic response. Finally, the absorber layer thickness of FACsSnI3 perovskite is tuned to achieve a maximum power-conversion efficiency of slightly more than 24%. We hope that the findings of this study will serve as a strong guideline for future research and the design of lead-free perovskite solar cells for efficient photovoltaic responses.

Comparison between different solar cells based on perovskite types

Perovskite solar cells (PSCs) are getting popular as promising photovoltaic technology due to their high efficiency and economical manufacturing costs. PSCs' effectiveness and stability have continuously improved in recent years, and research into minimizing lead leakage and creating environmentally acceptable lead-free perovskites is advancing the commercialization of PSCs step by step. The goal of this paper is to design a solar cell model based on getting higher light transmission and lower light reflection. Three-layer solar cell structure containing perovskite, titanium dioxide, and metal Nano layer sandwich between a silicon substrate and glass cover. The Maple 17 software is used to create the numerical results for the Transfer matrix, which determines the transmission and reflection of the incident light for various physical parameters of the structure. The results showed that the cell with aluminum cell has an excellent transmittance for a wide range of incident angles, perovskite thickness, and effective layer thickness. The short circuit current density reaches the most significant value at (𝛼 = 0), and it has zero value for parallel incidents. The cell of CH3NH3PbI3perovskite type and the aluminum metal nanolayer has the highest current density and a non-zero value for a wide range of incident angles.

An efficient all-perovskite two terminal monolithic tandem solar cell with improved photovoltaic parameters: A theoretical prospect

The wide photon absorption range of tandem solar cells (TSCs) allows them to deliver higher efficiencies than single-junction solar cells. The top cell with a wide bandgap absorbs the higher energy photons, while the bottom cell with a relatively low bandgap absorbs the filtered lower energy photons. However, for cheap, efficient, and long-lasting solar cells, the design must incorporate the top and bottom cell absorber layers with an appropriate band gap. In this context, this article proposes all-perovskite tandem solar cells with suitable perovskite partners as active materials in both the upper (band gap 1.68 eV) and the lower (band gap 1.16 eV) sub-cell. This research has retrieved the calibrated top cell from a previous publication, and the bottom cell has been designed, calibrated, and optimised. The filtered spectrum of the upper cell is evaluated at different perovskite thicknesses and fed to the lower cell to set up a tandem configuration. Subsequently, the current- matching technique has been used to study the tandem short-circuit current density (JSC) at different thicknesses of both sub-cells, followed by current density-voltage (J-V) curve. A total of ten tandem J-V curves are constructed and corresponding PV parameters are obtained to obtain the optimized efficiency of 33.8% with an open circuit voltage (VOC) of 2.15 V, a fill factor (FF) of 78.87% and a JSC of 20 mA.cm−2. The reported results will open the door for future development of highly efficient and low-cost monolithic two-terminal tandem devices.

Solar cell capacitance simulation and experimental photovoltaic performance analysis of perovskite solar cell based on CsGeI3

In this study, the experimental results of the perovskite solar cell with FTO/TiO2/CsGeI3/spiro-OMeTAD/Pt cell architecture are compared with the simulated results obtained using SCAPS-1D. Optimizations have been carried out by changing TiO2 ETL with CdS and Cd0.5Zn0.5S and spiro-OMeTAD HTL with inorganic CuI, Cu2O, CuSCN and NiO, thickness of perovskite, ETL, HTL and the temperature to formulate a high-performance perovskite solar cell. The impact of varying absorber thickness, ETL and temperature exhibit very minimal or no change. However, the simulated device exhibits high power conversion (4.94% to 7.12%) efficiency by replacement of TiO2 with Cd0.5Zn0.5S. Further, the impact of change of inorganic HTLs have also been studied by considering Cd0.5Zn0.5S as ETL. All inorganic HTLs outperformed well with almost similar cell efficiency (∼19.9%); NiO being highest. Therefore, analyzing all the results, we suggest that to draw a high-power conversion efficiency Cd0.5Zn0.5S shall be chosen as ETL possessing 95 nm layer thickness, 10 nm thick NiO as HTL and keep the absorber thickness 795 nm. Thus, the structure of the simulated solar cell device FTO/Cd0.5Zn0.5S/CsGeI3/NiO/Pt having such cell characteristics can be considered in the manufacturing workflow for its mass-scale production.

Design and optimization of four-terminal mechanically stacked and optically coupled silicon/perovskite tandem solar cells with over 28% efficiency

Silicon/perovskite tandem devices are believed to be a favorite contender for improving cell performance over the theoretical maximum value of single-junction photovoltaic (PV) cells. The present study evaluates the design and optimization of four-terminal (4-T) mechanically stacked and optically coupled configurations using SCAPS (solar cell capacitance simulator). Low-cost, stable, and easily processed semitransparent carbon electrode-based perovskite solar cells (c-PSCs) without hole transport material (HTM) and highly efficient crystalline silicon (c-Si) PV cells were utilized as top and bottom cells, respectively. The wide bandgap multi-cation perovskite Csx(FA0.4MA0.6)1−xPbI2.8Br0.2 and a low bandgap c-Si were employed as light-harvesting layers in the top and bottom cells, respectively. The impact of perovskite thickness and doping concentrations were examined and optimized for both tandem configurations. Under optimized conditions, thicknesses of 1000 nm and 1100 nm are the best values of the perovskite absorber layer for 4-T mechanically stacked and optically coupled arrangements, respectively. Likewise, 1 × 1017 cm−3 doping concentration of top cells revealed the highest performance in both structures. With these optimized parameters under tandem configurations, efficiency values of 28.38% and 29.34% were obtained in 4-T mechanically and optically coupled tandems, respectively. Results suggest that by optimizing perovskite thickness and doping concentration, the proposed designs using HTM-free c-PSCs could enhance device performance.

A Comprehensive Analysis of Eco‐Friendly Cs2SnI6 Based Tin Halide Perovskite Solar Cell through Device Modeling

AbstractThe choice of appropriate materials is of paramount importance in realizing a high efficiency perovskite solar cell. Lead free eco‐friendly perovskite solar cell architecture is theoretically investigated using solar cell capacitance simulator (SCAPS) for device performance. Preliminary investigations on Cs2SnI6 solar cell architectures have indicated that the presence of hole transport layer is crucial in achieving an open‐circuit voltage greater than 0.6 V. The presence of a valence band offset between the Cs2SnI6 absorber and hole transport layer has a significant detrimental impact on the short‐circuit current density and fill factor of the cell. A novel device architecture employing TiO2 as an electron transport material and Cu2O as a hole transport material is proposed to overcome the limitations associated with the current designs. Theoretical investigations are carried out employing 1D SCAPS simulation program in order to optimize the structure by varying the perovskite thickness, bandgap, and defect concentration. The proposed solar cell after optimization has a practically realizable power conversion efficiency of 17.77%.

Effect of conversion efficiency of electroluminescence and solar cell with change of perovskite thickness

Evidence suggests that the combination of a diode structure with a hybrid organic-inorganic perovskite may give rise to multifunctional device phenomena, such as the high power conversion efficiency of a solar cell and the strong electroluminescence efficiency of a light-emitting diode. This might open the door for the creation of a device with several uses. These multifunctional devices have a limited ability to approach the Shockley-Queisser efficiency limit due to the nonradiative losses that lower the open circuit voltage (Voc) . Here, we investigate and quantify the radiative limit of current carrying capacity in a perovskite solar cell as a function of absorber thickness. We seek to get a deeper understanding of the limiting elements that contribute to a low Voc by developing a link between PCE and EL efficiency over a variety of thicknesses. The efficiency of power conversion increases with increasing perovskite thickness, whereas the efficiency of energy conversion declines. To control light while also minimisingnonradiative losses, it is necessary to consider both of these figures of merit of a solar cell and tie them together. The findings suggest that increasing the efficiency of absorption and emission is critical for enhancing device performance.

Design and defect study of Cs2AgBiBr6 double perovskite solar cell using suitable charge transport layers

This work modelled and analysed perovskite solar cells based on Cs2AgBiBr6 with various electron transport layers and hole transport layers. The device structure is fluorine-doped tin oxide (FTO)/ZnO/Cs2AgBiBr6/NiO/Au. Power conversion efficiency (PCE) is practically saturated after the perovskite thickness of 700 nm. PCE declines from 21.88% to 1.58% when carrier lifetime decreases from 103 ns to 10−1 ns. Deep-level defects at mid-band gap energy of the perovskite layer can trap both carriers, allowing greater carrier recombination. Carrier capture cross-sectional area greatly impacts on cell performance. When subjected to high temperatures (T), the carrier mobility would diminish because carrier scattering increases cell resistance. That is why by raising T from 300 K to 400 K, the value of built-in potential (V bi) decreases from 1.17 V to 0.98 V. Device shows maximum efficiency when FTO is used as the front electrode, and Au is used as a back electrode. The optimum device, made of FTO/ZnO/Cs2AgBiBr6/NiO/Au, provides V oc = 1.29 V, J sc = 20.69 mA cm−2, fill factor = 81.72%, and PCE = 21.88%.

Comparative Study of the Correlation between Diffusion Length of Charge Carriers and the Performance of CsSnGeI3 Perovskite Solar Cells

Due to their enhanced performance and simplicity in manufacturing, scalability, and versatility, lead-halide perovskite-based solar cells (HPSCs) have received much attention in the domains of energy. Lead is present in nature as a poisonous substance that causes various issues to climate and human health and prevents its further industrialization. Over the past few years, there has been a noticeable interest in exploring some alternative lead-free perovskites. However, owing to some intrinsic losses, the performance that may be achieved from these photovoltaics is not up to standards. Thus, for the purpose of efficiency improvement, a comprehensive simulation is required to comprehend the cause of these losses. In the current research, an investigation into how to employ the promisingly efficient lead-free, all-inorganic cesium tin–germanium iodide (CsSnGeI3) perovskites as the photoactive layer in HPSCs was performed. Results exhibited a high efficiency of 12.95% with a CsSn0.5Ge0.5I3 perovskite thickness of 0.6 μm and a band gap of 1.5 eV at room temperature. High efficiency may be achieved using phenyl-C61-butyric acid methyl ester (PCBM) as an electron transport material because of its favorable energy-level alignment with the perovskite material. The research further tested the perovskite layer thickness and defect density in depth. The results showed that the carrier diffusion lengths have a big effect on how well the HPSC works.

Perovskite solar cells based on screen-printed thin films.

One potential advantage of perovskite solar cells (PSCs) is the ability to solution process the precursors and deposit films from solution1,2. At present, spin coating, blade coating, spray coating, inkjet printing and slot-die printing have been investigated to deposit hybrid perovskite thin films3-6. Here we expand the range of deposition methods to include screen-printing, enabled by a stable and viscosity-adjustable (40-44,000 cP) perovskite ink made from a methylammonium acetate ionic liquid solvent. We demonstrate control over perovskite thin-film thickness (from about 120 nm to about 1,200 nm), area (from 0.5 × 0.5 cm2 to 5 × 5 cm2) and patterning on different substrates. Printing rates in excess of 20 cm s-1 and close to 100% ink use were achieved. Using this deposition method in ambient air and regardless of humidity, we obtained the best efficiencies of 20.52% (0.05 cm2) and 18.12% (1 cm2) compared with 20.13% and 12.52%, respectively, for the spin-coated thin films in normal devices with thermally evaporated metal electrodes. Most notably, fully screen-printing devices with a single machine in ambient air have been successfully explored. The corresponding photovoltaic cells exhibit high efficiencies of 14.98%, 13.53% and 11.80% on 0.05-cm2, 1.00-cm2 and 16.37-cm2 (small-module) areas, respectively, along with 96.75% of the initial efficiency retained over 300 h of operation at maximum power point.

Overcoming the Outcoupling Limit of Perovskite Light-Emitting Diodes with Artificially Formed Nanostructures.

The external quantum efficiency (EQE) of state-of-the-art planar-structure perovskite light-emitting diodes (PeLEDs) is mainly limited by the outcoupling efficiency, which is around 20% and decreases significantly with the perovskite thickness. Here, an approach to artificially form textured perovskite films to boost the outcoupling limit of the PeLEDs is reported. By manipulating the dwell time of antisolvents, the perovskite phase precipitation mechanism, film-forming process, and surface texture can be finely controlled. The film surface roughness can be tuned from 15.3 to 241 nm, with haze increasing accordingly from 6% to >90% for films with an average thickness of 1.5 µm. The light outcoupling limit increases accordingly from 11.7% for the flat PeLEDs to 26.5% for the textured PeLEDs due to photon scattering at the interface. Consequently, the EQE is boosted significantly from around 10% to 20.5% with an extraordinarily thick emissive layer of 1.5 µm. This study provides a novel way of forming light-extraction nanostructures for perovskite optoelectronic devices.

Long‐Term Field Screening by Mobile Ions in Thick Metal Halide Perovskites: Understanding Saturation Currents

Metal halide perovskite‐based semiconductor devices with micrometer‐to‐millimeter‐thick perovskite layers show a current response upon polarization which evolves up to several hours, transiting several regimes. This is the case of X‐ray detectors where the use of absorber perovskites produces instabilities in the dark reverse saturation current hindering the signal processing. Even though these phenomena are often attributed to the electronic–ionic conductivity and the interface phenomena in these perovskites, a proper theoretical description is missing. Herein, the numerical simulation study reproduces the main experimental trends and explains the origin of some of the apparently‐always‐increasing current transients in thick perovskite samples. The mobile ion concentration and mobility are correlated with three main transport regimes and interpretation and parameterization are provided to the current saturation time in terms of the ionic screening of the electric field toward the interfaces. The final steady‐state under reverse polarization is found as diffusion‐limited electronic current, which results from abrupt mobile ion depletion proportional to the Debye length in the vicinity of a contact. The conclusions suggest the material optimization of the contact interfaces as a pathway to reduce the long current saturation times in these devices.

Investigating the potential of CuSCN as hole transport layer for perovskite solar cells for applications in indoor photovoltaics

Indoor photovoltaics (IPV) has recently emerged as a sustainable and reliable energy technology to power the rapidly growing Internet of Things. Among various solar cell technologies, emerging perovskite solar cells (PSCs) have gained great interest for IPV; owing to their unique optoelectronic properties such as bandgap tunability to efficiently harvest the indoor light spectrum. The choice of hole transport layer (HTL) is critical for efficient PSCs, particularly in IPV applications to reduce the parasitic absorption losses in the indoor light spectrum. Here, we explore the potential of CuSCN to be used as a HTL for PSCs in IPV applications. We show that CuSCN-based PSC exhibits remarkable power conversion efficiency (η) as compared to PSCs using conventional PEDOT:PSS as HTL. We explore the effects of wavelength (λ) of incident photons and various design parameters of PSC for optimal cell operations. We show that at a particular perovskite thickness, CuSCN-based PSC exhibits ∼8%–12% higher η than that for PEDOT-based PSC, for all λ in the visible range of the spectrum. We further explore the effect of HTL doping/thickness on PSC performance and show that CuSCN-based PSC performs optimally for a wide range of doping/thickness of HTL. We also find that CuSCN-based PSC outperforms PEDOT-based PSC for a broad range of incident irradiance. Finally, we show that for large values of λ (i.e. λ = 700 nm), η exceeds 30%, close to the highest ever in the past work. The work presented in this study will provide guidance for the development of efficient PSCs for indoor applications.

High Moisture Stability for Enhanced Quality Perovskite Solar Cells Induced by Front and Back Layer Synergistic Passivation of Perovskite

Moisture stability is one of the key factors that hinders the commercialization of perovskite solar cells (PSCs). Herein, a new method of front and back layer synergistic passivation of perovskite is investigated. On the front layer, porous PbI2 nanostructures are induced by N‐tert‐butyl‐2‐benzothiazolesulfenamide (TBBS), which is added into PbI2 precursor solution and thermally decomposed to tert‐butylamine (TBA) and 2‐mercaptobenzothiazole (2‐MBT) during annealing process. TBA volatilization leaves voids to induce porous PbI2, promoting diffusion of organic salts, facilitating crystallization of perovskite. Thickness of perovskite with TBBS doping increases from 527.7 to 561.2 nm, and the champion power conversion efficiency (PCE) increases from 19.71% to 20.97%. On the back layer, hydrophobic hole transport material PTAA is introduced onto perovskite surface to fill cation vacancies. Eventually, the highest efficiency of 22.35% with outstanding moisture stability is achieved after front and back layer synergistic passivation, which can maintain 71.14% of its initial efficiency after 7 days under high relative humidity (RH = 65 ± 2%) in ambient conditions without any encapsulation, while the control one can only remain 12.38%.