Promising Photovoltaic Technology Research Articles

Self-encapsulated wearable perovskite photovoltaics via lamination process and its biomedical application

Flexible perovskite solar cells (PSCs) are highly promising photovoltaic technologies due to the prospect of integration with wearable devices. However, conventional encapsulation strategies for flexible devices often cause secondary damage to the perovskite crystals, which affects device performance. Here, we present self-encapsulated flexible PSCs realized by lamination technology. The conversion of perovskite crystals is achieved by the diffusion of lead iodide and ammonium halide under the effect of temperature and pressure. In addition, the hydrogen bonding of the introduced polyacrylamide enhances the connections of the integral device while improving the crystal quality. The self-encapsulated flexible PSCs achieve an outstanding photovoltaic conversion efficiency of 22.33%, and comprehensive stability tests are conducted based on wearable device application scenarios to verify the feasibility. Finally, 25cm2 wearable perovskite modules are successfully applied into the neuro-assisted wearable devices.

A review on computational modeling of instability and degradation issues of halide perovskite photovoltaic materials

AbstractHybrid halide perovskite solar cells have been recognized as one of the most promising future photovoltaic technologies due to their demonstrated high‐power conversion efficiency, versatile stoichiometry and low cost. However, degradation caused by environmental exposure and structural instability due to ionic defect migration hinders the commercialization of this technology. While the experimental studies try to understand the phenomenology of the degradation mechanisms and devise practical measures to improve the stability of these materials, theoretical studies have attempted to bridge the gaps in our understanding of the fundamental degradation mechanisms at different time and length scales. A deeper understanding of the physical and chemical phenomena at an atomic level through multiscale materials modeling is going to be crucial for the knowledge‐based prognosis and design of future halide perovskites. There have been increased efforts in this direction in the last few years. However, the instability fundamentals explored through atomistic modeling and simulation methods have not been reviewed comprehensively in the literature yet. Therefore, this paper is an attempt to present a critical review, while identifying the existing gaps and opportunities in the investigation of the degradation and instability issues of the halide perovskites using computational methods. The review will primarily focus on the instability caused due to the intrinsic ionic defect migration and degradation due to thermal, moisture and light exposure. The findings from the simulation studies conducted primarily using density functional theory, ab initio molecular dynamics, classical molecular dynamics and machine learning methods will be presented.This article is categorized under: Software > Molecular Modeling Structure and Mechanism > Computational Materials Science Data Science > Artificial Intelligence/Machine Learning

Improving Photovoltaic Performance and Stability of Perovskite Solar Cells via Molecular Bridge Strategy

AbstractAlthough perovskite solar cells (PSCs) are regarded as one of the most promising photovoltaic technologies, the interfacial defects and energy barrier are the main bottlenecks for further improving their photovoltaic performance and stability. Herein, an effective, facile “molecular bridge” strategy to improve the photovoltaic performance and stability of PSCs simultaneously is reported. This strategy is realized by introducing a self‐assembly molecule, namely, 5‐fluoro‐pyridine carboxylic acid (5‐FPA), to modify the SnO2/perovskite buried interface. The functional groups (F and CO) of 5‐FPA form strong chemical interactions with perovskite and SnO2 layers, which improve interfacial carrier extraction and perovskite film quality with better crystallization and less strain. As a result, photovoltaic performance is substantially improved with power conversion efficiencies exceeding 23%, accompanied by enhanced stability under thermal and ambient conditions. This study opens a new avenue to improve the performance and stability of perovskite photovoltaics through the “molecular bridge” strategy.

High-Performance Perovskite Solar Cells and Modules Fabricated by Slot-Die Coating with Nontoxic Solvents.

Energy shortage has become a global issue in the twenty-firt century, as energy consumption grows at an alarming rate as the fossil fuel supply exhausts. Perovskite solar cells (PSCs) are a promising photovoltaic technology that has grown quickly in recent years. Its power conversion efficiency (PCE) is comparable to that of traditional silicon-based solar cells, and scale-up costs can be substantially reduced due to its utilization of solution-processable fabrication. Nevertheless, most PSCs research uses hazardous solvents, such as dimethylformamide (DMF) and chlorobenzene (CB), which are not suitable for large-scale ambient operations and industrial production. In this study, we have successfully deposited all of the layers of PSCs, except the top metal electrode, under ambient conditions using a slot-die coating process and nontoxic solvents. The fully slot-die coated PSCs exhibited PCEs of 13.86% and 13.54% in a single device (0.09 cm2) and mini-module (0.75 cm2), respectively.

Research on solar cells based on electron transport layer

In today ' s world, the energy crisis and environmental pollution are becoming more and more serious. As a renewable energy, solar energy has become one of the important means to meet the global energy demand. Making solar cells using volt effect is an effective way to convert solar energy into electricity. In order to employ solar photovoltaic power generating technology with high efficiency and cheap cost, new solar cell research and development is being done. Among them, organic solar cells are considered as one of the promising solar photovoltaic technologies because of their light weight, simple preparation process, good flexibility and easy to achieve large area processing. While perovskite solar cells are developed in a high speed in recent year because of their simple production and long service life. The urgent problem in this field is further improve the energy conversion efficiency of solar cells. In order to solve these problems, we study the structure principle and electron transport layer of solar cells, and get solutions by analyzing these problems.

Chemical Design of Organic Interface Modifiers for Highly Efficient and Stable Perovskite Solar Cells

AbstractPerovskite solar cells (PSCs) have demonstrated rapid progress in their power conversion efficiencies (PCEs)—from 3.8% in 2009 to 25.7% in 2022—and they have received considerable attention as a promising future photovoltaic (PV) technology. However, the operational stability of PSCs is still inadequate to satisfy the standards for commercial applications. Interface engineering has become one of the most important strategies to push PSCs’ efficiency and stability for practical use. Among the various interface engineering approaches, organic interface modifiers (OIMs) have been frequently used by the PSC field to address the issues limiting PSC stability at high efficiency levels. In this perspective, the chemical structures of state‐of‐the‐art OIMs are discussed, and their characteristics are reviewed, as well as the impact on device performance associated with key device interfaces (e.g., metal oxide/perovskite and organic transport layer/perovskite interfaces) from a chemical and materials engineering point of view is discussed. Design considerations and the authors' perspective are discussed, on the basis of representative literature examples, for building new, customized organic OIMs to further improve PSC efficiency and stability toward commercialization.

Carbon-Based Electrodes for Organic Solar Cells.

Organic solar cells (OSCs) are a promising low-cost thin-film photovoltaic technology while the fabrication of transparent conductive oxide (TCO) and metal electrodes still remains a factor that hinders the scaling-up and commercialization of OSCs. Carbon-based materials are regarded as potential alternatives due to their excellent properties, such as low cost, solution processibility, high conductance, and good chemical stability. In this mini-review, the recent progress of carbon-based materials such as graphite, carbon nanosheets, graphene, and carbon nanotubes to replace the TCO and metal electrodes of OSCs is surveyed. The preparation methods of different carbon-based materials are also discussed. Based on current progress, we summarize the outlooks and challenges of carbon-based electrodes. We anticipate this mini-review will inspire more research efforts to develop high-performance and OSC-matched carbon materials for more efficient and stable carbon-electrode-based OSCs.

Monitoring the stability and degradation mechanisms of perovskite solar cells by in situ and operando characterization

Solar energy technologies are among the most promising renewable energy sources. The massive growth of global solar generating capacity to multi-terawatt scale is now a requirement to mitigate climate change. Perovskite solar cells (PSCs) are one of the most efficient and cost-effective photovoltaic (PV) technologies with efficiencies reaching the 26% mark. They have attracted substantial interest due to their light-harvesting capacity combined with a low cost of manufacturing. However, unsolved questions of perovskite stability are still a concern, challenging the potential of widespread commercialization. Thus, it is imperative to advance in the understanding of the degradation mechanism of PSCs under in situ and operando conditions where variable and unpredictable stressors intervene, in parallel or sequentially, on the device stability. This review aims to debate the advantages behind in situ and operando characterization to complement stability-testing of PV parameters in the strive to achieve competitive stability and reproducibility in PSCs. We consider the impact of applying single and multi-stressors under constant monitoring of alterations observed in PSC components or complete devices. We outline key future research directions to achieve the long-term stability necessary for the successful commercialization of this promising PV technology.

All-Perovskite Tandem Solar Cells: From Certified 25% and Beyond

Perovskite-based solar cells are a promising photovoltaic technology capable of offering higher conversion efficiency at low costs compared with the standard of the market. They can be produced via a thin film technology that allows for considerable environmental sustainability, thus representing an efficient, sustainable, flexible, and light solution. Tandem solar cells represent the next step in the evolution of photovoltaics (PV). They promise higher power conversion efficiency (PCE) than those currently dominating the market. The tandem solar cell design overcomes the limitations of single junction solar cells by reducing the thermal losses as well as the manufacturing costs. Perovskite has been employed as a partner in different kinds of tandem solar cells, such as the Si and CIGS (copper indium gallium selenide) based cells that, in their tandem configuration with perovskite, can convert light more efficiently than standalone sub-cells. This brief review presents the main engineering and scientific challenges in the field. The state-of-the-art three main perovskite tandem technologies, namely perovskite/silicon, perovskite/CIGS, and perovskite/perovskite tandem solar cells, will be discussed, providing a side-by-side comparison of theoretical and experimental efficiencies of multijunction solar cells.

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.

Predicting power conversion efficiency of binary organic solar cells based on Y6 acceptor by machine learning

Organic solar cells (OSCs) are a promising photovoltaic technology for practical applications. However, the design and synthesis of donor materials molecules based on traditional experimental trial-and-error methods are often complex and expensive in terms of money and time. Machine learning (ML) can effectively learn from data sets and build reliable models to predict the performance of materials with reasonable accuracy. Y6 has become the landmark high-performance OSC acceptor material. We collected the power conversion efficiency (PCE) of small molecular donors and polymer donors based on the Y6 acceptor and calculated their molecule structure descriptors. Then we used six types of algorithms to develop models and compare the predictive performance with the coefficient of determination (R2) and Pearson correlation coefficient (r) as the metrics. Among them, decision tree-based algorithms showed excellent predictive capability, especially the Gradient Boosting Regression Tree (GBRT) models based on small molecular donors and polymer donors exhibited that the values of R2 are 0.84 and 0.69 for the testing set, respectively. Our work provides a strategy to predict PCEs rapidly, and discovers the influence of the descriptors, thereby being expected to screen high-performance donor material molecules.

Constructing Additives Synergy Strategy to Doctor-Blade Efficient CH3 NH3 PbI3 Perovskite Solar Cells under a Wide Range of Humidity from 45% to 82.

Perovskite solar cells (PSCs) have emerged as one of the most promising and competitive photovoltaic technologies, and doctor-blading is a facile and robust deposition technique to efficiently fabricate PSCs in large scale, especially matching with roll-to-roll process. Herein, it demonstrates the encouraging results of one-step, antisolvent-free doctor-bladed methylammonium lead iodide (CH3 NH3 PbI3, MAPbI3 ) PSCs under a wide range of humidity from 45% to 82%. A synergy strategy of ionic-liquid methylammonium acetate (MAAc) and molecular phenylurea additives is developed to modulate the morphology and crystallization process of MAPbI3 perovskite film, leading to high-quality MAPbI3 perovskite film with large-size crystal, low defect density, and ultrasmooth surface. Impressive power conversion efficiency (PCE) of 20.34% is achieved for doctor-bladed PSCs under the humidity over 80% with a device structure of ITO/SnO2 /MAPbI3 /Spiro-OMeTAD/Ag. It is the highest PCEs for one-step solution-processed MAPbI3 PSCs without antisolvent assistance. The research provides a facile and robust large-scale deposition technique to fabricate highly efficient and stable PSCs under a wide range of humidity, even with the humidity over 80%.

Application of Natural Molecules in Efficient and Stable Perovskite Solar Cells.

Perovskite solar cells (PSCs), one of the most promising photovoltaic technologies, have been widely studied due to their high power conversion efficiency (PCE), low cost, and solution processability. The architecture of PSCs determines that high PCE and stability are highly dependent on each layer and the related interface, where nonradiative recombination occurs. Conventional synthetic chemical materials as modifiers have disadvantages of being toxic and costly. Natural molecules with advantages of low cost, biocompatibility, and being eco-friendly, and have improved PCE and stability by modifying both functional layers and interface. In this review, we discuss the roles of natural molecules on PSCs devices in terms of the perovskite active layer, interface, carrier transport layers (CTLs), and substrate. Finally, the summary and outlook for the future development of natural molecule-modified PSCs are also addressed.

Enhancing Charge Carrier Transport in the Carbon-Electrode-Based CsPbI2Br Perovskite Solar Cells via I/Br Homogenization Process Modulation and Oleic Acid Surface Passivation

The carbon-electrode-based CsPbI2Br perovskite solar cells (C-PSCs) are promising photovoltaic technology because of their enhanced stability and low cost. However, the CsPbI2Br film suffers from uneven surface morphology with stripes and the defect-rich surface, which are detrimental to the charge carrier transport between perovskite and carbon. Here, we demonstrate that the formation of stripes is directly related to the I/Br homogenization process during annealing. By introducing a pre-annealing treatment before high temperature annealing, the I/Br homogenization process is modulated and the stripe is successfully wiped off. Besides, enhanced charge carrier transport in the C-PSCs is achieved. Oleic acid (OA) is then introduced to modify the stripe-free perovskite film surface. It is revealed that the carboxyl group in the OA molecule can passivate the undercoordinated Pb ions, leading to further improved charge carrier transport. Eventually, a power conversion efficiency (PCE) of 15.57% is achieved, which is among the highest PCE for the CsPbX3-based C-PSCs. This work demonstrates that combining surface planarization with surface passivation is an effective strategy for developing highly efficient C-PSCs.

Orientation Engineering via 2D Seeding for Stable 24.83% Efficiency Perovskite Solar Cells

AbstractOrganic‐inorganic hybrid perovskite solar cells (PSCs) have been extensively researched as a promising photovoltaic technology, wherein the orientation of the perovskite film plays a crucial role in the power conversion efficiency (PCE) and stability. Here, a seed‐mediated method is developed to in situ grow a layer of 2D perovskite seed for epitaxial growth of 3D perovskite atop it to construct a high‐quality 2D/3D heterojunction. It is found that the epitaxial 3D perovskite film exhibits a preferred [112] direction, which is different from traditional perovskites with a preferred [001] orientation. The oriented perovskite film consists of large‐sized grains with low defect density, long charge‐carrier lifetime, and good stability, resulting in efficient PSCs with a champion efficiency of 24.83%. In addition, the devices exhibit high stability under ambient, thermal, and continuous light‐soaking conditions. This work provides an effective strategy for achieving high‐quality perovskite films with tunable orientation to simultaneously boost the efficiency and stability of PSCs.

Recent Progress of Helicene Type Hole-Transporting Materials for Perovskite Solar Cells.

Perovskite solar cells have emerged as one of the most promising photovoltaic technologies for future clean energy sources to replace fossil fuels. Among the various components in a perovskite solar cell, the hole-transporting materials play significant roles in boosting device performance and stability. Recently, hole-transporting materials with helicene cores have received much attention due to their unique properties and ability to improve the performance and stability of the perovskite solar cells. The focus of this review is on the emerging special class of HTMs based on helicenes for perovskite solar cells. The optical, electrochemical, thermal and photovoltaic properties of helicene-based small molecules as HTMs or interfacial layer materials in n-i-p or p-i-n type perovskite solar cells are summarized. Finally, perspectives for the future development of helicene type hole-transporting materials are provided.

Interfacial Contact Management in Perovskite Solar Cells with Carbon Top Electrode

Perovskite solar cells (PSCs) represent a promising photovoltaic technology that has great potential for mass application. The main advantages of the perovskite solar cells are related to simplicity of their fabrication, tunable optical properties, and low cost of active materials. For further reducing the device costs, graphite‐based contacts are often used to replace an energy‐inefficient deposition of metal contacts, which is a trade‐off between the cost and power conversion efficiency (PCE) of devices. Herein, a new approach to increase the PCE of hole transport layer‐free perovskite cells with carbon‐based electrodes by the sequential treatment of the perovskite absorber layer and perovskite/carbon electrode interface with methylammonium iodide is presented. The proposed passivation technique leads to a dramatic improvement in the device power conversion efficiency from the initial 3.9% to 7.9%. The origin of the enhanced device performance is attributed to the passivation of defects on the perovskite/carbon interface and, most importantly, improving the electrical contact between the top electrode and absorber layer.

Self-assembled monolayers as hole-transporting materials for inverted perovskite solar cells

On the basis of the anchoring group, three categories of self-assembled monolayer hole-transporting materials in high-performance inverted perovskite solar cells are discussed.

Thermally cross-linkable fluorene-based hole transporting materials: synthesis, characterization, and application in perovskite solar cells.

Perovskite solar cells are among the most promising photovoltaic technologies in academia and have the potential to become commercially available in the near future. However, there are still a few unresolved issues regarding device lifetime and fabrication cost of perovskite solar cells in order to be competitive with existing technologies. Herein, we report small organic molecules with introduced vinyl groups as hole transporting materials, which are capable of undergoing thermal polymerization, forming solvent-resistant 3D networks. Novel compounds have been synthesized from relatively inexpensive starting materials and their purification is less time-consuming when compared to polymers; therefore this type of hole transporter can be a promising alternative to lower the manufacturing cost of perovskite solar cells.

Progress in organic photovoltaics based on green solvents: from solubility enhancement to morphology optimization.

Solution-processed organic photovoltaics (OPVs) is one of the most promising photovoltaic technologies in the energy field, due to their clean and renewable low-cost manufacturing potential. OPV has rapidly developed with the design and synthesis of highly efficient photovoltaic materials and the development of smart device engineering. To date, the majority of advanced OPV devices have been prepared using halogenated solvents, achieving power conversion efficiencies (PCE) exceeding 19% on a laboratory scale. However, for industrial-scale production, less toxic manufacturing processes and environmental sustainability are the key considerations. Therefore, this review summarizes recent advances in green solvent-based approaches for the preparation of OPVs, highlighting material design (including polymer donors and small molecule acceptors) and device engineering (co-solvent methods, additive strategies, post-treatment methods, and regulation of coating method), emphasizing crucial factors for achieving high performance in green solvent-processed OPV devices. This review presents potential future directions for green solvent-based OPVs, which may pave the way for future industrial development.