Organic-inorganic Hybrid Perovskite Solar Cells Research Articles

Enhancement of novel NaZnBr3 perovskite for solar cells application

The efficiencies of lead-based inorganic and organic–inorganic hybrid perovskite solar cells have been approaching 25% in recent years. Their major challenges include instability problems and their possible long term health hazards. In response to this, there has been a growth in research into lead-free inorganic perovskites. This research proposed that structural modifications of perovskite using copper and silver dopants be used as a unique technique for enhancing the efficiency of novel NaZnBr3. The optical, microstructural, electronic, and crystalline characterization was carried out using Ultraviolet–Visible (UV–VIS) spectroscopy, Scanning Electron Microscopy (SEM), SCAPS-1D, and X-ray Diffractometry (XRD) respectively. NaZnBr3 had an efficiency of 0.88% at 100μm, with a band gap of 3.1 eV. This efficiency improves to 9.33% with silver additive with a bandgap of 1.65 eV. Pure NaZnBr3 is found to be a p–n type semiconductor via its flat band potential, while doped NaZnBr3 are shown to be p-type semiconductors. Silver is concluded to be the better dopant, although both dopants increased the efficiency and show higher doping densities and external quantum efficiencies than pure NaZnBr3. It was reported that the crystallographic and microstructural structure of the perovskite plays a significant role in the optimization or modification of the efficiency of the novel NaZnBr3 perovskite. It is recommended that NaZnBr3 be researched further using different synthetic routes and experimental electronic measurement.

Progress in Organic-Inorganic Hybrid Perovskite Solar Cells: Architecture, Efficiency and Stability

In recent years, it has been established that solar cells based on organic-inorganic hybrid perovskite materials have substantial potential for the development of highly efficient photovoltaic devices and offers robust opportunities for research to the scientific community and industry. Power conversion efficiency (PCE) of perovskite solar cells (PSCs) have already surpassed 24.8 % within a decade, which is now third highest efficiency among single-junction photovoltaic materials. This report briefly introduces hybrid-halide perovskite materials, their structural properties, various possible device architectures and a comparative study of photo-voltaic performance. For commercialization, high stability of devices is must and here we have thoroughly discussed possible degradation mechanisms of PSCs, that is, moisture; oxygen; heat; structural stability; UV-light effect; defect-states, ion-migration and various approaches to passivity based upon recent reports. A proper encapsulation with optimized chemical composition (enhanced interaction between organic/inorganic cation and BX6 octahedron) PSCs could possess superior stability for long-run while maintaining optoelectronic properties.

Simulation of perovskite solar cells using molybdenum oxide thin films as interfacial layer for enhancing device performance

Organic-inorganic hybrid perovskite solar cells (PSCs) have the issue of interdiffusion at the interfaces that causes undesirable phenomena affecting device efficiency and stability. In this paper, we have investigated MoOx thin films as interlayer between the hole transport material and gold electrode and develop a model using the SCAPS solar cell simulator as a function of the interlayer film thickness to enhance device efficiency and stability. First, different thicknesses (2, 5, 10, 50, and 100 nm) of MoOx films were deposited on glass substrate by electron beam evaporation (e-beam) and their physical, chemical, optical, and electronic properties for PSC were examined. In this research, uniform, homogeneous and pinhole free MoOx films with high transmittance (˃ 80%), very low surface roughness, and resistivity were obtained from the 5 and 10 nm thick samples. In addition, the 10 nm film has shown the lowest photoluminescence emission. Using SCAPS solar cell simulation software and including MoOx thin films as passivation layer, the performance of the PSCs for a Pb-based and Pb-free perovskite absorber were modelled. Results showed that the 10 nm MoOx film is found to provide the best benefit to the device performance with enhanced power conversion efficiency (PCE) of 16.9% and 12.4% for the lead-based MAPb(I1-xBrx)3 and lead-free (MASnI3) perovskite solar cells, respectively.

Molecular Design and Cost-Effective Synthesis of Tetraphenylethene-Based Hole-Transporting Materials for Hybrid Solar Cell Application

The innovative choice of core and periphery groups for organic hole-transporting materials (HTMs) has gained more attention for modern development in hybrid organic–inorganic perovskite solar cells (PSCs). For large-scale application of PSCs, the replacement of 2,2′,7,7′-tetrakis(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene (spiro-OMeTAD) has its demands such as low stability, high cost, and multistep synthesis. This has necessitated the introduction of novel cost-effective HTMs. Hence, at first, we obtained a theoretical design of tetraphenylethene (TPE)-based HTMs through the Gaussian method, which exhibits a substantial highest occupied molecular orbital energy level as compared with the perovskite. Further, the photophysical, electrochemical, and thermal properties were meticulously investigated with the aid of both experimental and computational methods. In order to enhance the solubility of HTMs in chlorobenzene, the methoxy-substituted phenyl group was replaced with the hexyloxy-substituted phenyl group, and also, the higher extent of solubility is recognized after the functional group exchanges. The power conversion efficiencies of TOHE and TOME are η = 13.96%, Jsc = 21.00 mA/cm2, and Voc = 0.93 (V) and η = 6.83%, Jsc = 13.45 mA/cm2, and Voc = 0.97 (V), respectively (under full sunlight AM 1.5G, 100 mW cm–2 irradiation). Moreover, the synthesis of highly stable TOHE involves a simple and cost-effective synthetic procedure, proving to be the most promising lead for designing efficient organic–inorganic hybrid solar cells.

Interfacial Modification Engineering with Cs3Cu2I5 Nanocrystals for Efficient and Stable Perovskite Solar Cells

Ion defects at surface and grain boundaries (GBs) of perovskite films are paramount factors that influence the power conversion efficiency (PCE) of organic–inorganic hybrid perovskite solar cells (PSCs). Various methods have been proposed to solve the problems, but it still remains a great challenge because of the sophisticated and multiplicity of these defects. Herein, a modification method is developed that all‐inorganic low‐dimensional cesium copper halide nanocrystals (Cs3Cu2I5 NCs) are introduced to reduce the ionic defects of perovskite films at the surface and GBs. The champion device modified by Cs3Cu2I5 NCs exhibits remarkable promotion of PCE from 19.88% to 22.03% and fill factor from 74.09% to 82.21%. The results show that the solid‐state interdiffusion process occurs between the perovskite films and Cs3Cu2I5 NCs, which can improve the crystallinity, reduce interfacial recombination loss, and enhance the interfacial carrier transport in PSCs. Especially, the element distribution of Cs3Cu2I5 NCs in perovskite films affects the effectiveness of ionic defects passivation in the perovskite lattice. The PSCs device retains 91.6% of its initial PCE after 504 h under high moisture conditions. This work demonstrates an interfacial engineering strategy using the characteristic perovskite NCs, which provides a passivation method to achieve the high‐performance PSCs.

FAPbI3 Perovskite Solar Cells: From Film Morphology Regulation to Device Optimization

Organic–inorganic hybrid perovskite solar cells (PSCs) have attracted great attentions due to their rapid increase of power conversion efficiency (PCE). Although the highest PCE of PSCs (25.7%) has been achieved via using formamidinium lead iodide (FAPbI3) with a suitable bandgap, there is still a lack of systematic analysis on FAPbI3‐based PSCs toward high stability and high efficiency. Herein, the progress in FAPbI3 films and achievements in their high‐efficiency and long‐term stability PSCs are comprehensively reviewed. First, the progress from the aspects of morphology, defect, dimension, and strain for FAPbI3 film optimization is summarized and then the development of FAPbI3 PSCs in both efficiency and stability is discussed. Then, the methods to improve the FAPbI3 film quality by morphology control, defect passivation, dimensional regulation, and strain engineering, as well as strategies to optimize the device structure and interface layers, which are critical to promote device stability and efficiency, are evaluated. Finally, the outlook and strategies for realizing commercialized FAPbI3 PSCs with high efficiency and long lifetime are discussed.

Design of multifunctional near-infrared organic heterojunction and double hole transport layer to improve efficiency and stability of perovskite solar cells

• Single-walled carbon nanotubes acts as a double hole transport layer. • Multifunctional bulk organic heterojunction provides additional light harvesting. • Heterojunction and buffer layer enhance the stability of perovskite solar cells. Currently, the high-efficiency lead organic–inorganic hybrid perovskite solar cells (PSCs) can only utilize a relatively small fraction of sunlight (300–800 nm) due to the limited tunability of optical bandgap, which is the key factor limiting the further improvement of the photoelectric conversion efficiency (PCE) of PSCs. Here, we report a method to blend the narrow band gap non-fullerene acceptor molecule Y18 and the wide band gap donor molecule PM6 to form a multifunctional bulk organic heterojunction active layer. To avoid the loss of voltage and fill factor caused by the compromised hole transport layer (HTL), we introduce the single-walled carbon nanotubes as a buffer layer to fabricate a double HTL. The champion device displays a PCE improvement from 20.05% to 22.82% with a relative increase of 13.81%. After a deep examination of the mechanism, organic heterojunction provides the multifunctional roles as follows: (1) providing additional harvesting to the near-infrared light ranging of 800–950 nm; (2) passivating the perovskite surface and grain boundary to reduce the defect density; (3) promoting hole extraction from perovskite to HTLs by forming cascade energy levels. Moreover, the stability of PSCs is considerably enhanced because the introduction of organic heterojunction and buffer layer design isolated the natural degradation, which enhances the tolerance towards water and oxygen. Finally, a module group is fabricated by connecting two series modules in parallel, which is served as a power source to light the diode screen. This work demonstrates a buffer layer design for fabricating organic heterojunction-perovskite integrated solar cells to expand the near-infrared response, which provides a novel approach for designing integrated solar cells in the future.

Improved water repellency and environmental stability of perovskite solar cells by encapsulating with paraffin wax

Hybrid organic-inorganic metal halide perovskite solar cells are the fastest growing cost-effective photovoltaic technology because of their solution processability and lightweight properties. However, the poor stability of perovskite materials in presence of moisture is the main hindrance to their outdoor applications. Here, paraffin wax is explored as an encapsulating material for improving the water repellency of perovskite solar cells. For this purpose, the drop of paraffin from a burning candle is placed on the device area composed of methylammonium lead iodide as a perovskite material and doped poly(3-hexylthiophene) as a hole-transporting layer. The encapsulation does not affect the photovoltaic performance of the tested devices in ambient conditions, exhibiting the same performance as in an inert atmosphere. Moreover, the photovoltaic performance of the encapsulated solar cells remains unchanged even after 2160 h under ambient conditions with continuous exposure to the relative humidity in the range of 70–85%. The encapsulation is so robust that the photovoltaic performance of the cells does not change even after immersing the encapsulated cell in water or after heating at 85 °C. This performance of paraffin coating is superior to many reported sealing agents, which are deposited using costly instruments or by multistep processes. Thus, the paraffin exhibits the potential to be used as an alternative low-cost coating material for perovskite solar cells.

Interface Engineering in Solution-Processed Thin-Film Solar Cells

ConspectusAlong with the rapid industrialization of human society over the past century, incessant energy consumption and endless damage to the environment have aroused growing attention for seeking clean and renewable energy sources. Photovoltaics (PV) that can directly harvest and transform sunlight into electricity have shown great potential in achieving this goal. Especially for solution-processed thin-film solar cells, their extremely cost-effective and facile processing methods compatible with different substrates at large scales exhibit unique advantages over conventional PVs based on crystalline silicon. Various types of solution-processed thin-film PVs have been achieving or already exceeded 15% power conversion efficiency (PCE) through the numerous efforts of researchers. Organic solar cells (OSCs) and organic–inorganic hybrid perovskite solar cells (PVSCs) are the most well-known emerging solution-processed thin-film solar cells that have attracted great interest recently (the PCE of PVSCs soared form 3.8% to over 25% in the past decade). Usually, photogenerated excitons will form as a response to illumination in the active layer, then dissociate into charge carriers, travel in between layers, and finally get collected by electrodes of the device. Besides the broad exploration of active layer materials, suitably matched charge-transporting layers and electrodes also play a vital role in achieving high PCE and stability in PV devices. Furthermore, interfaces between different functional layers created during solution processing need to be carefully addressed to ensure efficient charge transport and prevent degradation. The utilization of proper interfacial materials to modify the chemical and electrical properties at interfaces has become an effective strategy to enhance the performance of PV. Therefore, it is important to develop a comprehensive understanding into the correlation between interfacial properties and charge carrier dynamics and establish molecular design principles for interfacial materials to realize commercialization of emerging PVs.In this Account, we first introduce the fundamental roles of interfaces in PVs, including the modulation of film formation, together with management of charge transport and recombination. Detailed analysis of interfaces and related surface science are also discussed to provide better understanding. Then, we highlight our research on interfacial materials with different functionalities including self-assembled monolayers, dopants, functional molecules for post-treatment, and composite materials. Combining with the fundamental mechanisms and design criteria of interfacial materials, new materials and interface engineering strategies can be integrated into other PV systems to achieve high PCE and stability. In the end, the main challenges and future perspectives toward the commercialization of solution-processed thin-film PVs are discussed to inspire more novel material designs and interface engineering.

Study of black phosphorus quantum dot modified SnO2-based perovskite solar cells

Organic–inorganic hybrid perovskite solar cells are considered promising due to their strong light absorption capability, long carrier diffusion distance, and rapid increase in energy conversion efficiency in the past decade. However, there is a high concentration of defects between the perovskite layer and the electron transport layer, which can lead to limited carrier extraction and, thus, affect the device efficiency. Black phosphorus quantum dots (BPQDs) have the advantages of tunable bandgap size, high absorption coefficient, and high electron mobility. Therefore, we introduced black phosphorus quantum dots (BPQDs) in aqueous SnO2 colloidal solution by laser liquid-phase ablation to improve the carrier extraction rate and reduce the trap density. By characterizing the prepared complete devices, we found that the device efficiency reached 15.83% after the introduction of BPQDs, which is 12% higher compared to 14.06% for the blank sample. Our work provides a simple and fast method to enhance the efficiency of perovskite solar cells.

Interpretation of Rubidium-Based Perovskite Recipes toward Electronic Passivation and Ion-Diffusion Mitigation.

Rubidium cation (Rb+ ) addition is witnessed to play a pivotal role in boosting the comprehensive performance of organic-inorganic hybrid perovskite solar cells. However, the origin of such success derived from irreplaceable superiorities brought by Rb+ remains ambiguous. Herein, grain-boundary-including atomic models are adopted for the accurate theoretical analysis of practical Rb+ distribution in perovskite structures. The spatial distribution, covering both the grain interiors and boundaries, is thoroughly identified by virtue of synchrotron-based grazing-incidence X-ray diffraction. On this basis, the prominent elevation of the halogen vacancy formation energy, improved charge-carrier dynamics, and the electronic passivation mechanism in the grain interior are expounded. As evidenced by the increased energy barrier and suppressed microcurrent, the critical role of Rb+ addition in blocking the diffusion pathway along grain boundaries, inhibiting halide phase segregation, and eventually enhancing intrinsic stability is elucidated. Hence, the linkage avalanche effect of occupied location dominated by subtle changes in Rb+ concentration on electronic defects, ion migration, and phase stability is completely investigated in detail, shedding a new light on the advancement of high-efficiency cascade-incorporating strategies and perovskite compositional engineering.

Effect of chlorine and bromine on the perovskite crystal growth in mesoscopic heterojunction photovoltaic device

Organic-inorganic hybrid perovskite solar cells are within the emerging photovoltaic technologies. The combination of different halogen ions, in certain fill fractions, is one of the methods to improve the perovskite film properties. Herein, fabrication and characterization of perovskite cells in standard mesoscopic architecture using one-step deposition method has been done. The role of the halogen ions (Chlorine or Bromine) on crystal structure growth and photoelectric performance has been investigated. X-ray diffraction, scanning electron microscopy, atomic force microscopy and optical microscopy analysis were performed. The microstructure, composition and morphology of CH3NH3PbI1.8Br1.2 and CH3NH3PbI1.8Cl1.2 films are dissimilar, although identical fabrication method was used. Same holds for optical properties, band gap energies of 1.84 eV and 1.63 eV, respectively, being obtained. Integrated in solar cells, the maximum power conversion efficiency of the Br based devices is beyond 10%, while for those based on Cl, the efficiency drops around 5%.

Ion Migration in Organic-Inorganic Hybrid Perovskite Solar Cells: Current Understanding and Perspectives.

Organic-inorganic hybrid perovskite (OIHPs) solar cells are the most promising alternatives to traditional silicon solar cells, with a certified power conversion efficiency beyond 25%. However, the poor stability of OHIPs is one of the thorniest obstacles that hinder its commercial development. Among all the factors affecting stability, ion migration is prominent because it is unavoidable and intrinsic in OHIPs. Therefore, it is important to understand the mechanism for ion migration and regulation strategies. Herein, the types of ions that may migrate in OHIPs are first discussed; afterward, the migrating channels are demonstrated. The effects of ion migration are further elaborated. While ion migration can facilitate the p-i-n structure in some cases, the current hysteresis and other adverse effects such as phase segregation in OHIPs attract widespread attention. Based on these, several recent strategies to suppress the ion migration are enumerated, including the introduction of alkali cations, organic additives, grain boundaries passivation, and employment of low-dimensional perovskites. Finally, the prospect for further modulating the ion migration and more stable perovskite solar cells is proposed.

Combining in-situ formed PbI2 passivation and secondary passivation for highly efficient and stable planar heterojunction perovskite solar cells

Since the power conversion efficiencies of organic-inorganic hybrid perovskite solar cells have a rapid development due to their high light absorption coefficient, tunable band gap and low fabrication cost, they have received much attention. The thin film formation and properties have significant effects on the final device performance. While how to control the thin film evolution and introduce film passivation is a critical issue to improve the device efficiency. In this study, we studied the controlled in-situ PbI 2 formation during the thin film evolution, and its effect on thin film properties, as well as their passivation effects on the photovoltaic device performance. The final thin film properties are critically related with the precursor used and chlorine inclusion could change the final thin film compositions, and affect the solar cell performance. We further perform a secondary passivation by reacting the excess PbI 2 with large organic cation to form 2D perovskite. Based on in-situ PbI 2 passivation and secondary 2D perovskite passivation, the devices exhibit a higher PCE of 21.1% and excellent V oc of 1.14 V. • Controlled in-situ PbI2 formation during the film evolution is achieved. • 2D perovksites as secondary surface passivation by reacting the excess PbI2. • A higher PCE of 21.1% and excellent V oc of 1.14 V are achieved via controlled in-situ PbI2 and 2D perovksite passivation.

Application of EDTA/SnO<sub>2</sub> double-layer composite electron transport layer to perovskite solar cells

Organic-inorganic hybrid perovskite solar cell devices have received wide attention because of their high efficiency, and interface problem is one of the key problems in the preparation of perovskite solar cells. An efficient double-layered ethylene diamine tetraacetic acid (EDTA)/SnO<sub>2</sub> composite structure, the ultrathin EDTA layer in contact with ITO electrode and an SnO<sub>2</sub> layer interfaced with the perovskite, is developed as an electron-transport layer (ETL) in the preparation of perovskite solar cells. It is interesting that the surface morphology of the top SnO<sub>2</sub> side of the composite ETL can be finely adjusted by tuning the underneath EDTA layer. These control the nucleation process in crystallization of the perovskite layer and adjust carrier extraction process between the electron transport and perovskite layers. High performance perovskite solar cells having a certified power conversion efficiency of 20.2% with negligible hysteresis are achieved.

Recent advances in the interfacial engineering of organic–inorganic hybrid perovskite solar cells: a materials perspective

Interfacial engineering of perovskite solar cells and its key roles are highlighted, and an overview of the recent advances in their related strategies using different materials in improving the photovoltaic performance and stability is given.

Perovskitne solarne ćelije - dosadašnji razvoj i perspektive

The energy conversion efficiency of hybrid organic-inorganic perovskite solar cells (PSCs) has reached a value comparable to commercially available silicon solar cells. The main challenges for their commercialization are instability and toxicity.

Application of ionic liquids for charge transport improvement in perovskite solar cells

The hybrid organic–inorganic perovskite solar cells (PSCs) exhibit a huge potential in the photovoltaic (PV) community due to a number of outstanding properties of the perovskite materials. Despite the device efficiencies of PSCs approaching to those based on crystalline silicon, this emerging PV technology still needs to overcome several bottlenecks including material stability and device lifetime. One of the strategies is the replacement of TiO2 electron-transport layer with SnO2, which has a lower photocatalytic effect and requires lower processing temperatures. The current work demonstrates an effective surface treatment of SnO2 electron-transport layer (ETL) by the application of 1-ethyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (EMPTFSI) ionic liquid (IL). The characterization results indicate a significant improvement of charge extraction efficiency at the interface of ETL/perovskite after the IL surface treatment, resulting in an enhancement of the power conversion efficiency (PCE) of PSCs from 18.1% to 19.3%. The obtained preliminary results will be discussed in this paper.

Efficient and stable carbon-based CsPbBr<sub>3</sub> solar cells added with PEABr additive

<sec>In recent years, organic-inorganic hybrid perovskite solar cells have become a research hotspot in the photovoltaic field because of their excellent power conversion efficiency. However, this hybrid perovskite material's intrinsic instability and the harsh preparation environment limit its further commercial application. All-inorganic CsPbBr<sub>3</sub> perovskite materials have attracted much attention because of their good stability, low cost and can be prepared in an atmospheric environment, showing great application potential. The controllable preparation and growth kinetics of CsPbBr<sub>3</sub> materials need to be further studied, and the conversion efficiency of photovoltaic devices is still low. Considering the instability caused by traditional organic hole transport materials and their high preparation cost, this work focuses on the systematical studies of CsPbBr<sub>3</sub> all-inorganic perovskite cells without a hole transport layer. Growth kinetics material of CsPbBr<sub>3</sub> is controlled by adding 2-phenylethylamine bromide to precursor solution<sub>.</sub> The main research contents and results are described as follows.</sec><sec>Based on multi-step spin-coating preparation of CsPbBr<sub>3</sub> perovskite films, the perovskite cell preparation method is studied, and the critical process parameters including the spin-coating PbBr<sub>2</sub>, amount and number of spin-coating of CsBr, substrate preheating temperature, and the annealing temperature, are optimized. The optimization tests show that the optimal spin-coating of CsBr is obtained by being optimized five times and the spin-coating PbBr<sub>2</sub> is conducted in the atmospheric environment. The optimal preheating temperature of the substrate is 80 ℃, and the optimal annealing temperature is 100 ℃. The perovskite films prepared under this condition are compact, each with a continuous high phase purity and good crystallization performance.</sec><sec>The PbBr<sub>2</sub> in DMF is first adopted and the 2-phenylethylamine bromide (PEABr) solution is added to regulate the CsPbBr<sub>3</sub> crystalline quality of the film. The effects of PEABr on the perovskite crystallization process and device performance are systematically investigated. The results show that the introduction of PEABr can effectively optimize the CsPbBr<sub>3</sub>. The crystalline properties of the two-dimensional perovskite materials can improve the grain boundaries and improve their transport properties. The prepared perovskite solar cell with PEABr shows the highest power conversion efficiency of 8.25%, and it can maintain the efficiency of more than 90% when being stored for 1500 h under the condition of no encapsulation. Finally, stable, efficient and low-cost all-inorganic CsPbBr<sub>3</sub> solar cells without a hole layer are obtained.</sec>

High Performance Htm-Free Organic-Inorganic Hybrid Perovskite Solar Cells Based on a Boron Dipyrrole Derivative

High Performance Htm-Free Organic-Inorganic Hybrid Perovskite Solar Cells Based on a Boron Dipyrrole Derivative