Structure Perovskite Solar Cells Research Articles

Low-Temperature Chemical Bath Deposition of Conformal and Compact NiOX for Scalable and Efficient Perovskite Solar Modules.

A scalable and low-cost deposition of high-quality charge transport layers and photoactive perovskite layers are the grand challenges for large-area and efficient perovskite solar modules and tandem cells. An inverted structure with an inorganic hole transport layer is expected for long-term stability. Among various hole transport materials, nickel oxide has been investigated for highly efficient and stable perovskite solar cells. However, the reported deposition methods are either difficult for large-scale conformal deposition or require a high vacuum process. Chemical bath deposition is supposed to realize a uniform, conformal, and scalable coating by a solution process. However, the conventional chemical bath deposition requires a high annealing temperature of over 400 °C. In this work, an amino-alcohol ligand-based controllable release and deposition of NiOX using chemical bath deposition with a low calcining temperature of 270 °C is developed. The uniform and conformal in-situ growth precursive films can be adjusted by tuning the ligand structure. The inverted structured perovskite solar cells and large-area solar modules reached a champion PCE of 22.03% and 19.03%, respectively. This study paves an efficient, low-temperature, and scalable chemical bath deposition route for large-area NiOX thin films for the scalable fabrication of highly efficient perovskite solar modules.

Unraveling Optical and Electrical Gains of Perovskite Solar Cells with an Antireflective and Energetic Cascade Electron Transport Layer

Electron transport layers (ETLs) are imperative in n-i-p structured perovskite solar cells (PSCs) because of their capability to affect light propagation, electron extraction, and perovskite crystallization, and any mismatch of optical constants, band position, and surface potential between the ETLs and the perovskites can cause unintentional optical and electrical losses. Herein, an antireflective and energetic cascade bilayer ETL with ubiquitously used SnO2 and TiO2 was constructed at 150 °C for PSCs, and the in-depth mechanism for performance improvement was systematically unraveled. It was revealed that the construction of an ETL with gradually increasing refractive indices can circumvent light reflection loss, resulting in enhanced photocurrent. The combined ETL forms an energetic cascade to promote electronic conductivity and facilitate electron extraction with reduced energy loss. Moreover, topologic perovskite growth with improved crystallinity and vertical orientation was preferred owing to the relative dewetting behavior, leading to reduced defect states and enhanced carrier mobility in the perovskite layer.

Exploring the Effect of Kesterites and Zinc‐Based Charge Transport Materials on the Device Performance and Optoelectronic Properties of FAPbI3Perovskite Solar Cells

Formamidinium lead triiodide (FAPbI3)‐based perovskite solar cells (PSCs) have shown greater structural stability but lower power conversion efficiency (PCE) than other established perovskites. The efficiency of the PSC can be improved by identifying suitable charge transport layers for FAPbI3, having good conductivity, and wide bandgap. Kesterite materials belonging to the adamantine family of chalcogenides are quaternary compounds with high conductivity and tunable bandgap. They have shown excellent results when employed in thin films and hence have emerged as an alternate option to be used for the hole transport layers (HTL). Similarly, zinc‐based materials have remarkable properties in terms of their wide bandgap, inability to oxidize, and abundance, making them a viable option to be explored as electron transport layers (ETL). Herein, six different kesterits are used as HTL to simulate FAPbI3PSC with four different zinc‐based ETL. Henceforth, a total of 24 structures is modeled and optimized using SCAPS‐1D. The effect of these materials on the optical absorption, quantum efficiency, electric field,I–Vcharacteristics, and recombination is studied. Among all the structures, CBTS/FAPbI3/CdZnS is found to be the best‐performing PSC structure with PCE of 28.55%, short‐circuit current of 26.8 mA cm−2, open‐circuit voltage of 1.19 V, and fill factor of 88.93%.

Comparative performance analysis of Cs2TiX6 (X = Br-, Cl-, I-) lead-free perovskite solar cells incorporating single, double and triple layer halides by SCAPS −1D

Halide perovskites have risen in popularity as appealing light absorber materials, owing primarily to their wide range of applications in solar cells, lasers, photodetectors. However, lead-containing perovskites have the potential to cause substantial environmental damage. As a result, there is a significant need to produce environmentally acceptable lead-free perovskites. In this work, we studied the single, double and triple halides perovskite by numerical simulator SCAPS-1D for maximum performance. We have optimized the absorber layer thickness, NA/ND/Nt and interface defect density, back contact electrodes, and temperature effects in a single absorber layer structure. Further, we have optimized the double and triple-layer absorbers for perovskite solar cell structures. The maximum efficiency achieved in the double halide perovskite solar cell is VOC = 1.54 V, JSC = 24.04 mA/cm2, FF = 82.72%, and PCE = 30.06%. Such performance is due to the absorption coefficient spectrum with a wide range of energy band gaps. This has proved its suitability for photovoltaic devices. Overall, our findings reveal that Cs2TiX6 (X = Br, Cl, I) Pb-free perovskites have promising and potential features for device performance.

Enhance and balance AVT and PCE of the semi-transparent perovskite solar cells for BIPV via grating-based photonic crystals

Semi-transparent perovskite solar cells attract significant attention in building-integrated photovoltaics, especially for solar window application. However, thinning the perovskite photoactive layer, setting up nanostructures in the perovskite layer, and improving the functional layer transparent can neither effectively balance the power conversion efficiency (PCE) and average visible transmittance (AVT), nor can it effectively resolve the issue of colorful transmitted light. Here, based on the light polarization-selective absorption characteristics of photonic crystals, a semi-transparent perovskite solar cell with the grating-based photonic crystals is presented. It can apply the original layer structure of high efficiency perovskite solar cells without any transparent replacement, including the retention of opaque electrodes. Through the developed multiphysics and multi-objective mathematical model, the semi-transparent FAPbI3 solar cells can be optimized with PCE of 10% and AVT of 60.3%. When PCE increases to 12%, 15%, and 17%, the corresponding AVTs are 52.6%, 41.1%, and 33.4%, respectively. The performance far exceeds the benchmark of PCE (10%) and AVT (25%) for solar window application. Also, the transmitted light remains white regardless of the values of AVT and PCE. Furthermore, the semi-transparent perovskite solar cells with the grating-based photonic crystals can exhibit stable high-performance when the dimension tolerance varies from 1% to 20%, which reduces the requirement of processing technology. In the end, a design and optimization guideline for the semi-transparent perovskite solar cells is proposed through the analyses on the effect of a broad incident angle. These findings provide effective design strategies for the semi-transparent perovskite solar cells in the context of building-integrated photovoltaics.

Device Structures of Perovskite Solar Cells: A Critical Review

In recent years, perovskite solar cells (PSCs) have been in huge demand because of their ease of production, low cost, flexibility, long diffusion length, lightweight, and higher performance than their counterparts. The PSCs have demonstrated remarkable progress with power conversion efficiency (PCE) up to 25.7% using FAPbI3 as an active layer component. However, lower PCE and device stability restrict PSCs' commercial viability. Further, the photocurrents in PSCs are close to the maximum Shockley–Queisser (SQ) limit. The focus now is on enhancing the open‐circuit voltage and fill factor through modifying charge‐selective contacts, the morphology of perovskite material, and interface modification. The large grain size, uniformity, and coverage area distinguish the crucial factors affecting the PCE of PSCs. Long‐term device stability and degradation mechanisms have also shown significant dependence on the device structure. Therefore, the tailoring of the device structure continues to play a crucial role in the device's performance and stability. In this review, the illustration of the structural development of perovskite solar cells, including advanced interfacial layers and their associated parameters, is discussed in detail. In addition, the challenges that hinder the PSCs' performance are also discussed.

Research on Preparation and Progress of Two-Dimensional Perovskite Solar Cells

Two-dimensional perovskite solar cells are considered as the most promising new type of solar cells due to their unique advantages such as strong spectral absorption, low cost, adjustable composition, excellent structure, excellent photoelectric characteristics and simple preparation through various processes. This paper will briefly introduce the structure and principle of two-dimensional perovskite solar cells, and introduce the research progress of top electrode materials in detail, including improving the preparation method of metal top electrode materials, repairing and introducing buffer layer and cathode intermediate layer for interface modification. High-performance perovskite solar cells use lead-containing perovskite materials as the light absorbing layer. Even if the device packaging process is perfect, lead-based perovskite materials still have the possibility of causing pollution to the environment, especially when the battery is damaged or the failed solar cells are improperly recycled. Therefore, in this paper, we can obtain high-quality perovskite films by improving the preparation process, solvent engineering and annealing engineering.

Optimizing inorganic double halide (Cs2TiI6) perovskite solar cell for different hole transport layers using solar cell capacitance software (SCAPS-ID)

Although the organic-inorganic Pb-based (CH3NH3PbI3) and Sn-based (CH3NH3SnI3) perovskite solar cells (PSC) have attained higher efficiency but due to toxicity and instability, the inorganic, Ti-based (Cs2TiI6) PSC can be a potential alternative. So, the current paper focuses on determining open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF), power conversion efficiency (PCE) and quantum efficiency (QE) for the inorganic PSC by changing temperature, thickness, band gaps and hole transport layers (HTLs) using solar cell capacitance software (SCAPS-ID). Three different types of Ti-based perovskite solar cell structures have been investigated by varying three types of HTL. Results yield that structure 1 (TCO/ZnO/Cs2TiI6/CdTe/Au) cedes higher PCE of 23.51 % with VOC 1.23 V, JSC 22.49 mA/cm2 and FF 84.77 % for the band gap of 1.7 eV and 500 nm thickness of the absorber layer, at 300 K temperature in comparison with other structures. The maximum efficiency of approximately 98 % has also been found for all simulated structures for the wavelength of around 360 nm.

The Latest Progress in Effect Factors and Related Applications of Perovskite Solar Cells

In recent years, the perovskite solar cells have attracted wide attention for its increasing power conversion efficiency (PCE), simple manufacturing process, low cost material components, light and simple wearable abilities and simple using conditions. Many researchers cooperate to improve the stability, efficiency, universality and operational repeatability of the perovskite solar cells. These efforts have taken a huge step forward in the field of perovskite solar cells and achieved a maximum PCE of 26.11%, which greatly encouraged staffs in the relevant fields. However, there are many factors restricting the continued development and practical application of perovskite solar cells. In this paper, the development and structure of perovskite solar cells are introduced, and different factors for its performance are carefully summarized including surface modification, electrolyte solution, working temperature and spectrum absorption. Moreover, its application in outer space, quantum dots and working temperature are also briefly presented. This work could provide some current practical application situation of perovskite solar cells. Finally, the development prospect of perovskite solar cells is briefly discussed.

Performance analysis and optimization of inverted inorganic CsGeI3 perovskite cells with carbon/copper charge transport materials using SCAPS-1D.

Organic-inorganic perovskite solar cells (PSCs) have achieved the power conversion efficiencies (PCEs) of more than 25%. However, the organic compound in the material is causing structural degradation of the PSC owing to heat (thermal instability), humidity and moisture. This has led to the exploration of only inorganic perovskite materials. Inorganic PSCs such as caesium have seen a breakthrough by achieving highly stable PSC with PCE exceeding 15%. In this work, the inorganic non-toxic PSCof caesium germanium tri-iodide (CsGeI3) is numerically modelled in SCAPS-1D with two carbon-based electron transport layers (ETLs) and two copper-based hole transport layers (HTLs). This study introduces in-depth numerical modelling and analysis of CsGeI3 through continuity and Poisson equations. Cu HTLs are selected to increase the electric conductivity of the cell, while carbon-based ETL is used toincrease the thermal conductivity of the PSC. A total of fourunique PSC structures are designed and presented. A systematic approach is adopted to obtain the optimized PSC design parameters for maximum performance. From the optimized results, it is observed that the C60/CsGeI3/CuSCN structure is the highest performance PSC, with open-circuit voltage (V oc) of 1.0169 V, short-circuit current density (J sc) of 19.653 mA cm-2, fill factor of 88.13% and the PCE of 17.61%. Moreover, the effect of quantum efficiency, electric field, interface recombination, interface defects, layer thickness, defect density, doping concentration, working temperature and reflection coating on the cell performance are studied in detail.

Theoretical study of a lead-free perovskite solar cell using ZnSe as ETL and PTAA as HTL

Cesium tin-germanium triiodide (CsSn0.5Ge0.5I3) is an efficient inorganic halide perovskite with good stability that has received wide attention in recent years. In the present study, a lead-free perovskite solar cell structure was designed with zinc selenide (ZnSe) as the electron transport layer (ETL), CsSn0.5Ge0.5I3 as the perovskite absorber layer and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) as the hole transport layer (HTL). For a more practical understanding of the solar cell, several parameters such as absorber thickness, defect density, doping concentration of the absorber layer, interface defects and working point temperature were examined. The SCAPS-1D simulator was used for the analysis of the proposed device. The power conversion efficiency of the device was obtained as 23.15% with V OC = 1.07 V, J SC = 27.24 mA/cm2 and fill factor = 78.82% at an 800 nm thickness of the CsSn0.5Ge0.5I3 absorber layer. Selection of best material and easy fabrication process is necessary for development of highly efficient and environmentally friendly perovskite solar cells.

Direct Measurements of Interfacial Photovoltage and Band Alignment in Perovskite Solar Cells Using Hard X-ray Photoelectron Spectroscopy.

A heterojunction is the key junction for charge extraction in many thin film solar cell technologies. However, the structure and band alignment of the heterojunction in the operating device are often difficult to predict from calculations and, due to the complexity and narrow thickness of the interface, are difficult to measure directly. In this study, we demonstrate a technique for direct measurement of the band alignment and interfacial electric field variations of a fully functional lead halide perovskite solar cell structure under operating conditions using hard X-ray photoelectron spectroscopy (HAXPES). We describe the design considerations required in both the solar cell devices and the measurement setup and show results for the perovskite, hole transport, and gold layers at the back contact of the solar cell. For the investigated design, the HAXPES measurements suggest that 70% of the photovoltage was generated at this back contact, distributed rather equally between the hole transport material/gold interface and the perovskite/hole transport material interface. In addition, we were also able to reconstruct the band alignment at the back contact at equilibrium in the dark and at open circuit under illumination.

Stable Methylammonium‐Free p‐i‐n Perovskite Solar Cells and Mini‐Modules with Phenothiazine Dimers as Hole‐Transporting Materials

During the last decade, perovskite solar technologies underwent an impressive development, with power conversion efficiencies reaching 25.5% for single‐junction devices and 29.8% for Silicon‐Perovskite tandem configurations. Even though research mainly focused on improving the efficiency of perovskite photovoltaics (PV), stability and scalability remain fundamental aspects of a mature photovoltaics technology. For n‐i‐p structure perovskite solar cells, using poly‐triaryl(amine) (PTAA) as hole transport layer (HTL) allowed to achieve marked improvements in device stability compared with other common hole conductors. For p‐i‐n structure, poly‐triaryl(amine) is also routinely used as dopant‐free hole transport layer, but problems in perovskite film growth, and its limited resistance to stress and imperfect batch‐to‐batch reproducibility, hamper its use for device upscaling. Following previous computational investigations, in this work, we report the synthesis of two small‐molecule organic hole transport layers (BPT‐1,2), aiming to solve the above‐mentioned issues and allow upscale to the module level. By using BPT‐1 and methylammonium‐free perovskite, max. Power conversion efficiencies of 17.26% and 15.42% on a small area (0.09 cm2) and mini‐module size (2.25 cm2), respectively, were obtained, with a better reproducibility than with poly‐triaryl(amine). Moreover, BPT‐1 was demonstrated to yield more stable devices compared with poly‐triaryl(amine) under ISOS‐D1, T1, and L1 accelerated life‐test protocols, reaching maximum T90 values >1000 h on all tests.

Manipulating Crystallographic Orientation via Cross-Linkable Ligand for Efficient and Stable Perovskite Solar Cells.

The crystallographic orientation of polycrystalline perovskites is found to be strongly correlated with their intrinsic properties; therefore, it can be used to effectively enhance the performance of perovskite-based devices. Here, a facile way of manipulating the facet orientation of polycrystalline perovskite films in a controllable manner is reported. By incorporating a cross-linkable organic ligand into the perovskite precursor solution, the crystal orientation disorder can be reduced in the resultant perovskite films to exhibit the prominent (001) orientation with a preferred stacking mode. Moreover, the as-formed low-dimensional perovskites (LDPs) between the organic ligand and the excess lead iodide can passivate the defects around the grain boundaries. Consequently, highly efficient p-i-n structured perovskite solar cells (PSCs) can be made in both rigid and flexible forms from modified perovskites to show high power conversion efficiencies (PCE) of 24.12% and 23.23%, respectively. The devices also exhibit superior long-term stability in a humid environment (with T90 > 1000h) and under thermal stress (retaining 87% of its initial PCE after 1000h). More importantly, the ligand enables the derived LDPs to be crosslinked (under 254nm UV illumination) to demonstrate excellent mechanical bending durability in flexible devices.

Optimization of lead-free CsSnI3-based perovskite solar cell structure

Abstract Perovskites are considered the most promising material for the latest generation of solar cells. However, due to the presence of lead in their composition, the development of non-toxic Perovskite cells has become an essential goal to enable their large-scale production. In this work, we have simulated, modeled and optimized the structure of a single solar cell that consists of a non-toxic cesium–tin–iodine CsSnI3 Perovskite absorber with a low band gap energy value of 1.3 eV, between TiO2 and PTAA materials as ETL and HTL layers, respectively. A simulation model describing the charge carrier processes and the effect of interface defect density is presented. Several structures based on alternative ETL and HTL materials are proposed. An optimal device structure is proposed based on the results obtained. An efficiency of 19.92% is obtained with V oc = 0.829 V, J sc = 30.68 mA/cm2 and FF = 73.33% using SnO2 and Spiro-OMeTAD as ETL and HTL materials. However, 29.22% is achieved using the optimal structure as the bottom cell in a tandem configuration.

Dopant‐Free Two‐Dimensional Hole Transport Small Molecules Enable Efficient Perovskite Solar Cells

AbstractDeveloping dopant‐free hole transport materials (HTMs) to replace Spiro‐OMeTAD is a challenging but urgent issue for commercialization of state‐of‐the‐art n‐i‐p structured perovskite solar cells (PSCs). Here, this work proposes an effective two‐dimensional conjugate engineering strategy to tune molecular stacking orientation and improve the hole mobility of dopant‐free small molecule HTMs. For the first time, triphenylamine (TPA) groups are incorporated as side chains of benzo [1,2‐b:4,5‐b′]dithiophene (BDT) unit to extend the longitudinal conjugate, achieving two donor‐acceptor‐acceptor type 2D small molecules, namely XF2 and XF3, which show a dominant face‐on orientation and better hole transport mobility than the linear small molecule XF1. The incorporation of alkoxy Lewis base groups makes XF3 a more effective defect passivator for perovskite surfaces. As a result, the PSCs using pristine XF3 HTM show a dramatically improved efficiency of 20.59% along with improved long‐term stability compared to that of XF1 HTM (power conversion efficiency (PCE) = 18.84%). A champion efficiency of 21.44% is achieved through device engineering for dopant‐free XF3‐based PSCs. The results show that the building block with longitudinal conjugate extension in small molecules plays an essential role in the face‐on orientation morphology and elucidates a key design rule for the dopant‐free small molecule HTMs for high‐performance PSCs.

Investigation of effect of doping in perovskite solar cells: A numerical simulation approach

In n -i-p structure perovskite solar cells, TiO 2 is a widely used thermally stable and low-cost electron transport layer. But in CsSnI 3 based perovskite solar cells, the undoped-TiO 2 electron transport layer does not provide proper band alignment for efficient charge transportation. The use of doped semiconductors in heterojunction solar cells has improved device performance significantly by shifting the energy levels of the electron and hole transport layers. We have investigated the effect of doping density in the absorber layer, electron transport layer, and hole transport layer on the performance of a device with an FTO/TiO 2 /CsSnI 3 /CuSCN/Au configuration. It is found that the doping density of the electron transport layer (TiO 2 ) and absorber layer (CsSnI 3 ) has a significant effect on the band alignment and thus on the device performance; however, an increase in the acceptor doping density of the hole transport layer (CuSCN) does not make any significant changes in the device performance. In addition, we have optimized the variable parameters of different layers. The optimized device shows an efficiency >25%. These results could help to optimize the performance of CsSnI 3 based n -i-p structure perovskite solar cells with TiO 2 electron transport layer.

Numerical study and optimization of GO/ZnO based perovskite solar cell using SCAPS

<abstract> <p>This paper focuses on the numerical study of hybrid organic-inorganic perovskite solar cells. It investigates the incorporation of a graphene oxide (GO) thin layer to enhance solar cell efficiency. The study demonstrates that the GO layer improves interaction with the absorber layer and enhances hole transportation, resulting in reduced recombination and diffusion losses at the absorber and hole transport layer (HTL) interface. The increased energy level of the Lower Unoccupied Molecular Orbital (LUMO) in GO acts as an excellent electron-blocking layer, thereby improving the V<sub>OC</sub>. The objective is to explore different structures of perovskite solar cells to enhance their performance. The simulated solar cell comprises a GO/FASnI<sub>3</sub>/TiO<sub>2</sub>/ZnO/ITO sandwich structure, with FASnI<sub>3</sub> and ZnO thicknesses adjusted to improve conversion efficiency. The impact of thickness on device performance, specifically the absorber and electron transport layers, is investigated. The fill factor (FF) changes as the absorber and electron transport layers (ETL) increase. The FF is an important parameter that determines PSC performance since it measures how effectively power is transferred from the cell to an external circuit. The optimized solar cell achieves a short-circuit current density (J<sub>SC</sub>) of 27.27 mA/cm<sup>2</sup>, an open-circuit voltage (V<sub>OC</sub>) of 2.76 V, a fill factor (FF) of 27.05% and the highest power conversion efficiency (PCE) of 20.39% with 400 nm of FASnI<sub>3</sub> and 300 nm of ZnO. These findings suggest promising directions for the development of more effective GO-based perovskite solar cells.</p> </abstract>

Oxysalt based synergistic dual interfacial engineering for high performance p–i–n structured perovskite solar cells

The synergistic effect of the double-sided passivation strategy using oxysalts led to improved performance of p–i–n perovskite solar cells.

Modeling Monte Carlo simulation on photon regeneration effects of perovskite FAPbI3 for photovoltaic applications.

Controlling the photon regeneration effects in FAPbI3 films is a noteworthy approach to improve the photovoltaic (PV) efficiency of FAPbI3-based solar cells. However, the lack of systematic study on the relationship between photon regeneration effects and PV efficiency in the experimental process makes it difficult to control the photon regeneration effects effectively. In this work, we combine the Monte Carlo sampling method and the polar coordinate calculation method to design a new algorithm for a detailed simulation of the main processes of photon regeneration effects affecting the PV efficiency in a model based on an n-i-p type FAPbI3 perovskite solar cell (PSC). The algorithm is validated to be used to compare the power-conversion efficiency (PCE) of different PSCs to filter out the PSC structure with the highest PCE or to determine the range of material parameter values corresponding to the highest PCE. This work opens up new ideas to effectively control the photon regeneration effects in PSCs to improve the device PV efficiency.