Component Of Perovskite Solar Cells Research Articles

Theoretical analysis of doping of perovskite light-absorbing layer for highly efficient perovskite solar cells

The physical properties of perovskites—the central components of perovskite solar cells (PSCs)—are crucial for photovoltaic (PV) performance. Suitable doping of perovskites can improve the electric-field distribution within them, thus enhancing their PV performance. In this study, the effects of the three doping strategies on PV performance of MAPbI3 based PSCs were explored. First, uniform acceptor doping of perovskite was performed. With increasing uniform acceptor doping concentration (NA), the open-circuit voltage (VOC) gradually increased, but the short-circuit current density (JSC) decreased. As the decline in JSC limited further PCE increase, non-uniform acceptor doping of perovskite was performed, which increased the width of the space-charge region near the MAPbI3/SnO2 interface, promoting the flow of holes from MAPbI3 to the carbon electrode. The JSC increased from 19.05 to 22.30 mA cm−2, and the power conversion efficiency (PCE) increased from 19.74 % to 22.72 % when the doping concentration curve for non-uniform acceptor doping was a line passing through 3 × 1018 and 3 × 1014. In order to further enhance the PCE, simultaneous non-uniform acceptor doping and uniform donor doping of perovskite was adopted, which further improved the JSC and fill factor (FF), and the PCE increased from 22.72 % to 23.92 % when the uniform donor doping concentration was 1 × 1018 cm−3. This work provides a strategy of doping of perovskite for highly efficient PSCs.

Pressure and temperature effects on the electron transport layer material for solar energy applications: a molecular dynamic approach explores the influence of environmental conditions of biostructure materials in solar cells

This investigation initiated by modelling the crystal structure of perovskite to explore the impact of different temperatures. Researchers modified the perovskite crystal structure and observed its response to temperature variations. The study involved assessing the efficiency and fill factor of perovskite solar cells, incorporating photovoltaic structures without specifying the electron transport layer material. The primary goal of this initiative is to provide power to buildings using environmentally acceptable components in perovskite solar cells. The promising efficiency and cost-effectiveness of manufacturing make perovskite solar cells an intriguing option for generating clean and sustainable energy.

Light management in perovskite solar cells

The optical properties of each component in perovskite solar cells (PSCs) affect their light-harvesting capability and thus the photocurrent generation and ultimate efficiency of the device. As the power conversion efficiency of PSCs approaches an achievable practical limit, light-management strategies have gained significant attention. In this review, comprehensive analyses of the optical losses of PSCs were conducted in comparison with those of other types of photovoltaics. Based on these results, past and recent progress in various light management technologies for realizing optical improvements were reviewed. Anti-reflection coatings, up and down conversions, plasmonic phenomena, and device structure adjustment have been used to ensure the effectiveness and potential of PSCs for optimum device operation. Finally, future perspectives are discussed to propose research directions for effective optical management.

Sustainable and Circular Management of Perovskite Solar Cells via Green Recycling of Electron Transport Layer‐Coated Transparent Conductive Oxide

AbstractTransparent conductive oxide (TCO)‐coated glasses are the most expensive and environmentally impacting components of perovskite solar cells (PSCs), comprising 56% of the total cost of a perovskite module and 96% of its carbon footprint. Thus, recycling TCO glasses from end‐of‐life perovskite modules can reduce both their levelized cost of electricity and energy payback time. In this work, tin oxide (SnO2)‐coated indium tin oxide glasses are refurbished from n‐i‐p PSCs employing dimethyl sulfoxide as a green solvent to dissolve the upper layers of the devices. Employing the recovered substrates, new‐generation PSCs are produced, which retain the same champion power conversion efficiency (PCE) of 22.6% as fresh samples and display an even higher average PCE. This performance enhancement is investigated through compositional and electrical analyses that demonstrate that the proposed recycling protocol induces beneficial surface modifications on the SnO2/perovskite interface and trap passivation, boosting charge extraction.

Cross-linked polyelectrolyte reinforced SnO2 electron transport layer for robust flexible perovskite solar cells

SnO2 electron transport layer (ETL) is a vital component in perovskite solar cells (PSCs), due to its excellent photoelectric properties and facile fabrication process. In this study, we synthesized a water-soluble and adhesive polyelectrolyte with ethanolamine (EA) and poly-acrylic acid (PAA). The linear PAA was crosslinked by EA, forming a 3D network that stabilized the SnO2 nanoparticle dispersion. An organic–inorganic hybrid ETL is developed by introducing the cross-linked PAA-EA into SnO2 ETL, which prevents nano particle agglomeration and facilitates uniform SnO2 film formation with fewer defects. Additionally, the PAA-EA-modified SnO2 facilitated a uniform and compact perovskite film, enhancing the interface contact and carrier transport. Consequently, the PAA-EA-modified PSCs exhibited excellent PCE of 24.34% and 22.88% with high reproducibility for areas of 0.045 and 1.00 cm2, respectively. Notably, owing to structure reinforce effect of PAA-EA in SnO2 ETL, flexible device demonstrated an impressive PCE of 23.34% while maintaining 90.1% of the initial PCE after 10,000 bending cycles with a bending radius of 5 mm. This successful approach of polyelectrolyte reinforced hybrid organic–inorganic ETL displays great potential for flexible, large-area PSCs application.

Extending the π‐Conjugated System in Spiro‐Type Hole Transport Material Enhances the Efficiency and Stability of Perovskite Solar Modules

AbstractHole transport materials (HTMs) are a key component of perovskite solar cells (PSCs). The small molecular 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl)‐amine‐9,9′‐spirobifluorene (spiro‐OMeTAD, termed “Spiro”) is the most successful HTM used in PSCs, but its versatility is imperfect. To improve its performance, we developed a novel spiro‐type HTM (termed “DP”) by substituting four anisole units on Spiro with 4‐methoxybiphenyl moieties. By extending the π‐conjugation of Spiro in this way, the HOMO level of the HTM matches well with the perovskite valence band, enhancing hole mobility and increasing the glass transition temperature. DP‐based PSC achieves high power conversion efficiencies (PCEs) of 25.24 % for small‐area (0.06 cm2) devices and 21.86 % for modules (designated area of 27.56 cm2), along with the certified efficiency of 21.78 % on a designated area of 27.86 cm2. The encapsulated DP‐based devices maintain 95.1 % of the initial performance under ISOS‐L‐1 conditions after 2560 hours and 87 % at the ISOS‐L‐3 conditions over 600 hours.

Extending the π-Conjugated System in Spiro-Type Hole Transport Material Enhances the Efficiency and Stability of Perovskite Solar Modules.

Hole transport materials (HTMs) are a key component of perovskite solar cells (PSCs). The small molecular 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl)-amine-9,9'-spirobifluorene (spiro-OMeTAD, termed "Spiro") is the most successful HTM used in PSCs, but its versatility is imperfect. To improve its performance, we developed a novel spiro-type HTM (termed "DP") by substituting four anisole units on Spiro with 4-methoxybiphenyl moieties. By extending the π-conjugation of Spiro in this way, the HOMO level of the HTM matches well with the perovskite valence band, enhancing hole mobility and increasing the glass transition temperature. DP-based PSC achieves high power conversion efficiencies (PCEs) of 25.24 % for small-area (0.06 cm2 ) devices and 21.86 % for modules (designated area of 27.56 cm2 ), along with the certified efficiency of 21.78 % on a designated area of 27.86 cm2 . The encapsulated DP-based devices maintain 95.1 % of the initial performance under ISOS-L-1 conditions after 2560 hours and 87 % at the ISOS-L-3 conditions over 600 hours.

Defect Passivation Scheme toward High-Performance Halide Perovskite Solar Cells.

Organic-inorganic halide perovskite solar cells (PSCs) have attracted much attention in recent years due to their simple manufacturing process, low cost, and high efficiency. So far, all efficient organic-inorganic halide PSCs are mainly made of polycrystalline perovskite films. There are transmission barriers and high-density defects on the surface, interface, and grain boundary of the films. Among them, the deep-level traps caused by specific charged defects are the main non-radiative recombination centers, which is the most important factor in limiting the photoelectric conversion efficiency of PSCs devices to the Shockley-Queisser (S-Q) theoretical efficiency limit. Therefore, it is imperative to select appropriate passivation materials and passivation strategies to effectively eliminate defects in perovskite films to improve their photovoltaic performance and stability. There are various passivation strategies for different components of PSCs, including interface engineering, additive engineering, antisolvent engineering, dopant engineering, etc. In this review, we summarize a large number of defect passivation work to illustrate the latest progress of different types of passivators in regulating the morphology, grain boundary, grain size, charge recombination, and defect density of states of perovskite films. In addition, we discuss the inherent defects of key materials in carrier transporting layers and the corresponding passivation strategies to further optimize PSCs components. Finally, some perspectives on the opportunities and challenges of PSCs in future development are highlighted.

Modeling the Electronic and Optical Properties of Lead-Based Perovskite Materials: Insights from Density Functional Theory and Electrostatic Embedding

We present an investigation of the geometric, electronic, and optical properties of various bulk MAPbX3 (X = Cl, Br, and I) perovskite systems in different phases and of different heterointerface models built between MAPbI3 (hereafter MAPI) and TiO2, linked by a bifunctional para-benzoic acid derivative, in view of their importance as key components of perovskite solar cells. To this end, we combine periodic hybrid density functional theory (DFT) calculations, to model the geometric and electronic properties of these systems, with time-dependent DFT calculations (TD-DFT) carried out on non-periodic clusters, extracted from the periodic models, embedded in an array of point charges reproducing the periodic electrostatic environment, thus enabling the modeling of their optical properties in condensed phases. We found that all systems investigated present favorable key features for their use as building blocks for solar devices. Furthermore, the proposed computational approach, combining periodic and non-periodic calculations, appears as a reliable and effective tool to model both the electronic and the optical properties of various key components of materials related to photovoltaic applications at low computational cost.

Low‐Temperature Synthesis of SnO2 Nanocrystals as Electron Transport Layers for High‐Efficiency CsPbI2Br Perovskite Solar Cells

Perovskite solar cells (PSCs) have recently become a hot topic in photovoltaics due to their high power conversion efficiency (PCE) and low‐cost processing. As a key component of PSCs, electron transport layers (ETLs) that play a vital role in efficient PSCs generally require high charge extraction ability, mobility, and easy fabrication. Herein, a simple route to obtain dispersion of tin oxide nanocrystals (SnO2 NCs) with uniform diameters and high stability as efficient ETLs for CsPbI2Br solar cells is demonstrated. The champion device achieves a remarkable PCE of 16.22% with an open‐circuit voltage of 1.30 V. This work offers a facile and effective way to fabricate high‐performance ETL nanocrystals in PSCs.

Phthalocyanines, porphyrins and other porphyrinoids as components of perovskite solar cells

This review highlights the most relevant works on phthalocyanines, porphyrins and other porphyrinoids as components of perovskite solar cells from the last four years acting as hole transporting materials, additives, and interlayers.

Green-Solvent-Processable Low-Cost Fluorinated Hole Contacts with Optimized Buried Interface for Highly Efficient Perovskite Solar Cells.

Solution-processed hole contact materials, as an indispensable component in perovskite solar cells (PSCs), have been widely studied with consistent progress achieved. One bottleneck for the commercialization of PSCs is the lack of hole contact materials with high performance, cost-effective preparation, and green-solvent processability. Therefore, the development of versatile hole contact materials is of great significance. Herein, we report two novel donor-acceptor (D-A)-type hole contact molecules (FMPA-BT-CA and 2FMPA-BT-CA) with low cost and alcohol-based processability by utilizing a fluorination strategy. We showed that the fluorine atoms lead to the lowered highest occupied molecular orbital (HOMO) energy levels and larger dipole moments for FMPA-BT-CA and 2FMPA-BT-CA. Moreover, fluorination also improves the buried interfacial interaction between hole contacts and perovskite. As a result, a remarkable power conversion efficiency (PCE) of 22.37% along with good light stability could be achieved for green-solvent-processed FMPA-BT-CA-based inverted PSC devices, demonstrating the great potential of environmentally compatible hole contacts for highly efficient PSCs.

Configurable Organic Charge Carriers toward Stable Perovskite Photovoltaics.

Due to their solution processability and unique photoelectric characteristics, perovskite solar cells (PSCs) have shown considerable promise in the area of renewable energy. Although their power conversion efficiency (PCE) has risen from 3.8% to 25.7% in only a few years, their short lifetime and high material prices continue to be key roadblocks to commercial viability. Charge transporting materials (CTMs), such as hole/electron transporting materials, are critical components in PSCs because they not only govern hole or electron extraction and transporting from the perovskite layer to the electrodes but also protect the perovskite from direct contact with the ambient environment. CTMs are split into two types: inorganic CTMs (ICTMs) and organic CTMs (OCTMs). Because of their inexpensive prices, well-adjusted energy levels, and low temperature solution-processed features, OCTMs have been more frequently explored and employed than ICTMs. Various forms of OCTMs with more straightforward synthetic pathways and better performance have been thoroughly researched. Recent achievements in the development of OCTMs will be discussed and evaluated on a molecular level in this study, which will include a systematic categorization of OCTMs based on molecular functionalization techniques. In order to achieve highly efficient and stable PSCs, we will present insights on the structure-property relationship in the design of OCTMs as well as device stability. We hope that this analysis will serve as a comprehensive reference to molecular design guidelines for various types of OCTMs, spurring greater research toward designing highly efficient and OCTMs for stable PSCs.

Bacteriochlorin aggregates as dopant-free hole-transporting materials for perovskite solar cells

Organic-inorganic hybrid perovskite solar cells (PSCs) have attracted great interests not only of academic field but also of industrial world toward practical applications in the last decade due to their extremely low production cost and excellent photo-physical properties. Hole-transporting layer (HTL) as an integral component of PSC plays an important role in elevating its performance. In this work, five bacteriochlorophyll- a derivatives characterized by different C17-propionate residue were prepared and their J- type aggregates were investigated as HTLs of PSCs. It was confirmed that the nature of the introduced C17-propionate side chains have negligible effects on the electrochemical properties of main dye unit, such as the electronic absorption spectra and energy levels. However, the different lipophilicity, hydrophilicity, or hydrophobicity of chain characters affect the solubility of each dye component, resulting in diverse surface morphologies of their aggregate films as revealed by AFM observations. Furthermore, the five solid films prepared by spin-coating method showed discrepant charge extraction and transport abilities as HTLs, which were supported by both photo luminescence spectra and electrochemical impedance spectroscopy measurement results and were concluded to be the fundamental reason of the different PSC performance. • Five bacteriochlorophyll- a derivatives were investigated as HTLs of PSCs. • PSC employing BChl-2 bearing a dodecyl ester as an HTL gives the highest PCE. • Charge transfer process and interfacial contact are the essential factors for HTLs.

Impact of Al on ZnO Electron Transport Layer in Perovskite Solar Cells

Perovskite solar cells have shown remarkable performance and improvements in terms of solar cell efficiency. The ETL material is one of the important components in perovskite solar cells in conducting electrons to produce current. Here, ZnO was used as ETL material in a perovskite solar cell using the SCAPS 1D simulation software. The ZnO ETL showed poor cell efficiency due to its reaction with the perovskite material. A small amount of Al doped into ZnO was introduced to enhance the physiochemical properties of the ZnO against perovskite materials. Al concentrations were varied between 1 and 4 mol% to observe the effect on cell efficiency. Compared with a conventional ZnO ETL solar cell with 0 mol% Al perovskite, the Al-doped based solar cell showed better performance. Meanwhile, perovskite solar cells with 1 mol% Al-doping and appropriate layer thickness showed the best cell performance in improving the charge transport mechanism, resulting in increased cell efficiency. Thus, the parameters studied can be a guide in the fabrication process.

Highly Efficient Dopant-Free Cyano-Substituted Spiro-Type Hole-Transporting Materials for Perovskite Solar Cells

The hole-transporting material (HTM) is an important component of perovskite solar cells (PSCs) because it plays a crucial role in achieving high performance. The most frequently used HTM is 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamino)-9,9′-spirobifluorene (Spiro-OMeTAD). Spiro-OMeTAD requires dopants such as Li(TFSI) to realize high power conversion efficiencies (PCEs). However, these dopants cause severe instability issues in PSCs. The Spiro-OMeTAD layer also tends to undergo severe morphological deformation at high temperature, which produces large voids and further reduces the cell performance. These drawbacks must be overcome for the commercialization of PSCs. Therefore, it is strongly desirable to develop high-performance dopant-free HTMs to replace Spiro-OMeTAD. Here, we synthesize two cyano-substituted spirobifluorene-based HTMs, SF27 and SF48, for this purpose. These compounds are derived from Spiro-N, which is a Spiro-OMeTAD analogue obtained via the replacement of the p-methoxy substituents with strong electron-donating p-N,N-dimethylamino groups. The influence of cyano substituents on the optoelectronic properties, PCEs, and charge transport behavior in PSCs are investigated. These compounds have a highest occupied molecular orbital energy level that is well-matched to the valence band of perovskite layers. The hole mobility of SF48 (o-cyano-substituted) was determined to be higher than that of SF27 (m-cyano-substituted), although it is lower than those of Spiro-OMeTAD and the reference compound Spiro-N. Mesoporous PSCs were fabricated using these new HTMs without dopants under relatively low HTM concentration conditions, and the cell performance was compared to that of devices with Spiro-OMeTAD and Spiro-N. The PSC with non-doped SF48 exhibited a high PCE of 18.7%, which is comparable to that of the reference PSCs with doped Spiro-OMeTAD (18.6%). In addition, the thermal stability of SF48 at 85 °C in air was superior to that of Spiro-OMeTAD, both with and without dopants. Therefore, the SF48 spirobifluorene-based compound is determined to be quite effective as a high-performance dopant-free HTM for PSCs.

Optimization of an inorganic lead free RbGeI3 based perovskite solar cell by SCAPS-1D simulation

The toxic lead component of perovskite solar cells poses a hindrance to their commercialization. The state-of-art organic HTM, Spiro-OMeTAD has a high synthetic cost because of its complex synthesis procedure. In the present work, an all inorganic, lead free n-i-p planar RbGeI3-based PSC was demonstrated through SCAPS-1D simulation. The effect of various HTL and ETL materials, their thickness, thickness of perovskite layer, ETL doping concentration, HTL doping concentration, doping concentration of the absorber, defect density of perovskite layer, defect density of ETL/absorber and absorber/HTL interface, various back contacts, series resistance, shunt resistance and temperature on the performance of perovskite solar cell (PSC) has been analysed. The optimized device exhibited a power conversion efficiency (PCE) of 10.11%, fill factor (FF) of 63.68% and quantum efficiency (QE) of 90.3% in the visible range. This study demonstrates the potential of RbGeI3 as a perovskite material to achieve toxicity free renewable energy.

Remarkable performance optimization of inverted p-i-n architecture perovskite solar cell with CZTS as hole transport material

Hole transport material (HTM) is a major component of perovskite solar cells (PSCs). PEDOT: PSS, an organic HTM, is widely used in inverted (p-i-n) PSCs. While PEDOT: PSS is unstable, expensive and it's acidic nature could deteriorate the absorber. Copper zinc tin sulphide (CZTS), an inorganic semiconductor can be used as HTM due to its properties such as low cost, ease of synthesis and high hole mobility. In this work, device simulation of inverted (p-i-n) PSC was performed with CZTS as HTM to exploit its maximum capability. Remarkable power conversion efficiency (PCE) of 25.43% was achieved after optimizing the performance. Device performance was strongly affected by thickness and electron affinity of HTM as well as diffusion length of carriers. PCE of real fabricated device was also found to be 9.72%. This work demonstrates CZTS is a promising candidate to replace PEDOT: PSS from both experimental and theoretical perspectives.

Cyclopentadiene‐Based Hole‐Transport Material for Cost‐Reduced Stabilized Perovskite Solar Cells with Power Conversion Efficiencies Over 23%

AbstractHole transport materials (HTM) are an important component in perovskite solar cells (PSC). Despite a multitude of HTMs developed in recent years, only few of them lead to solar cells with efficiencies over 20%. Therefore, it is still a challenge to develop high‐performing HTMs, which have ideal energy levels of the frontier orbitals, are highly efficient in transporting charges, and stabilize the solar cell at the same time. In this work, the development of a structurally novel molecular HTM, CPDA 1, is described which is based on a common cyclopentadiene core and can be efficiently and inexpensively synthesized from readily available starting materials, which is important for future realization of low‐cost photovoltaics on larger scale. Due to excellent optoelectronic, thermal, and transport properties, CPDA 1 not only meets the envisioned properties by reaching high efficiencies of 23.1%, which is among the highest reported to date, but also contributes to a respectable long‐term stability of the PSCs.

Constructing CdS-Based Electron Transporting Layers With Efficient Electron Extraction for Perovskite Solar Cells

The electron transporting layer (ETL) is a critical component in perovskite solar cells (PSCs) and plays an important role in extracting and transporting electrons. However, the commonly used wide-bandgap metal oxides (TiO2, ZnO, SnO2, etc.) often involve undesirable photocatalytic activity towards perovskite materials under UV light, which would undermine the long-term stability of PSCs. In this article, nonoxide CdS ultra-thin films were deposited onto conducting substrates through chemical bath deposition to serve as ETLs. It is revealed that the subsequent CdCl2 treatment followed by annealing is not essential to CdS ETLs for PSCs; this fact is quite different from the scenario demonstrated for conventional thin-film solar cells. Moreover, a compact TiO2 (c-TiO2) blocking layer was introduced between the conducting substrate and the CdS layer to further enhance the electron extraction capability of ETLs and boost the photovoltaic performance of PSCs. Through careful morphology, optical and electrical characterizations, it is found that the presence of the c-TiO2 underlayer avoids the partially exposure of substrate bumps, enlarges the subsequently deposited perovskite crystals, forms cascade energy level alignments, and accelerates the electron extraction from perovskite to ETLs. Therefore, the shunt current leakage and the charge recombination at the ETL/perovskite interface are significantly suppressed. Eventually, the CH3NH3PbI3 PSC based on the bilayer c-TiO2/CdS ETL yields a promising power conversion efficiency of 15.11%, which is much higher than that of the single-layer CdS-based device. This work delivers one of the few CdS ETL-based PSCs that exhibit efficiencies over 15%.