Plasmonic Effects of Metallic Nanoparticles on Enhancing Performance of Perovskite Solar Cells

Enhanced efficiency of carbon based all perovskite tandem solar cells via cubic plasmonic metallic nanoparticles with dielectric nano shells

This study investigates a carbon-based all-perovskite tandem solar cell (AP-TSC) with the structure ITO, SnO₂, Cs₀.₂FA₀.₈Pb(I₀.₇Br₀.₃)₃, WS₂, MoO₃, ITO, C₆₀, MAPb₀.₅Sn₀.₅I₃, PEDOT: PSS, Carbon. The bandgap configuration of the cell is 1.75 eV/1.17 eV, which is theoretically limited to 36% efficiency. The effectiveness of embedding cubic plasmonic metallic nanoparticles (NPs) made of Gold (Au) and Silver (Ag) within the absorber layers to eliminate the requirement for thicker absorber layers, decrease manufacturing costs and Pb toxicity is demonstrated in our analysis. This analysis was conducted using 3D Finite Element Method (FEM) simulations for both optical and electrical calculations. Prior to delving into the primary investigation of the tandem structure, a validation simulation was conducted to demonstrate the accuracy and reliability of the simulations. Notably, the efficiency mismatch observed during the validation simulation, specifically in relation to the incorporation of metallic nanoparticles (NPs), amounted to a mere 0.01%. To mitigate the potential issues of direct contact between metallic NPs and perovskite materials, such as increased thermal and chemical instability and recombination at the NP surface, a 5 nm dielectric shell was applied to the NPs. The incorporation of cubic core-shell Ag NPs resulted in a 15.32% enhancement in short-circuit current density, from 16.39 mA/cm² to 18.90 mA/cm², and a 15.68% increase in overall efficiency, from 26.9 to 31.12%. This research paves the way for the integration of core-shell metallic NPs in AP-TSCs, highlighting a significant potential for efficiency and stability improvements. In a dedicated section the band alignment of the sub-cell was addressed. Additionally, a thermal investigation of the proposed tandem structure was conducted, demonstrating the robustness of the proposed AP-TSC. Finally, the sensitivity analyses related to input parameters and the challenges associated with large-scale fabrication of the proposed AP-TSC were extensively discussed.

Plasmonics Meets Perovskite Photovoltaics: Innovations and Challenges in Boosting Efficiency

Perovskite solar cells (PSCs) have garnered immense attention in recent years due to their outstanding optoelectronic properties and cost-effective fabrication methods, establishing them as promising candidates for next-generation photovoltaic technologies. Among the diverse strategies aimed at enhancing the power conversion efficiency (PCE) of PSCs, the incorporation of plasmonic nanoparticles has emerged as a pioneering approach. This review summarizes the latest research advancements in the utilization of plasmonic nanoparticles to enhance the performance of PSCs. We delve into the fundamental principles of plasmonic resonance and its interaction with perovskite materials, highlighting how localized surface plasmons can effectively broaden light absorption, facilitate hot-electron transfer (HET), and optimize charge separation dynamics. Recent strategies, including the design of tailored metal nanoparticles (MNPs), gratings, and hybrid plasmonic-photonic architectures, are critically evaluated for their efficacy in enhancing light trapping, increasing photocurrent, and mitigating charge recombination. Additionally, this review addresses the challenges associated with the integration of plasmonic elements into PSCs, including issues of scalability, compatibility, and cost-effectiveness. Finally, the review provides insights into future research directions aimed at advancing the field, thereby paving the way for next-generation, high-performance perovskite-based photovoltaic technologies.

Synergetic Near- and Far-Field Plasmonic Effects for Optimal All-Perovskite Tandem Solar Cells with Maximized Infrared Absorption

The efficiency and reliability of perovskite solar cells have rapidly increased in conjunction with the proposition of advanced single-junction and multi-junction designs that allow light harvesting to be maximized. However, Sn-based compositions required for optimized all-perovskite tandem devices have reduced absorption coefficients, as opposed to pure Pb perovskites. To overcome this, we investigate near- and far-field plasmonic effects to locally enhance the light absorption of infrared photons. Through optimization of the metal type, particle size, and volume concentration, we maximize effective light harvesting while minimizing parasitic absorption in all-perovskite tandem devices. Interestingly, incorporating 240 nm silver particles into the Pb-Sn perovskite layer with a volume concentration of 3.1% indicates an absolute power conversion efficiency enhancement of 2% in the tandem system. We present a promising avenue for experimentalists to realize ultrathin all-perovskite tandem devices with optimized charge carrier collection, diminishing the weight and the use of Pb.

Models of light absorption enhancement in perovskite solar cells by plasmonic nanoparticles

Numerous experiments have demonstrated improvements on the efficiency of perovskite solar cells by introducing plasmonic nanoparticles, however, the underlying mechanisms are still not clear: the particles may enhance light absorption and scattering, as well as charge separation and transfer, or the perovskite's crystalline quality. Eventually, it can still be debated whether unambiguous plasmonic increase of light absorption has indeed been achieved. Here, various optical models are employed to provide a physical understanding of the relevant parameters in plasmonic perovskite cells and the conditions under which light absorption may be enhanced by plasmonic mechanisms. By applying the recent generalized Mie theory to gold nanospheres in perovskite, it is shown that their plasmon resonance is conveniently located in the 650-800 nm wavelength range, where absorption enhancement is most needed. It is evaluated for which active layer thickness and nanoparticle concentration a significant enhancement can be expected. Finally, the experimental literature on plasmonic perovskite solar cells is analyzed in light of this theoretical description. It is estimated that only a tiny portion of these reports can be associated with light absorption and point out the importance of reporting the perovskite thickness and nanoparticle concentration in order to assess the presence of plasmonic effects.

Plasmon-Enhanced Perovskite Solar Cells Based on Inkjet-Printed Au Nanoparticles Embedded into TiO2 Microdot Arrays

The exceptional property of plasmonic materials to localize light into sub-wavelength regimes has significant importance in various applications, especially in photovoltaics. In this study, we report the localized surface plasmon-enhanced perovskite solar cell (PSC) performance of plasmonic gold nanoparticles (AuNPs) embedded into a titanium oxide (TiO2) microdot array (MDA), which was deposited using the inkjet printing technique. The X-ray (XRD) analysis of MAPI (methyl ammonium lead iodide) perovskite films deposited on glass substrates with and without MDA revealed no destructive effect of MDA on the perovskite structure. Moreover, a 12% increase in the crystallite size of perovskite with MDA was registered. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) techniques revealed the morphology of the TiO2_MDA and TiO2-AuNPs_MDA. The finite-difference time-domain (FDTD) simulation was employed to evaluate the absorption cross-sections and local field enhancement of AuNPs in the TiO2 and TiO2/MAPI surrounding media. Reflectance UV-Vis spectra of the samples comprising glass/TiO2 ETL/TiO2_MDA (ETL-an electron transport layer) with and without AuNPs in TiO2_MDA were studied, and the band gap (Eg) values of MAPI have been calculated using the Kubelka-Munk equation. The MDA introduction did not influence the band gap value, which remained at ~1.6 eV for all the samples. The photovoltaic performance of the fabricated PSC with and without MDA and the corresponding key parameters of the solar cells have also been studied and discussed in detail. The findings indicated a significant power conversion efficiency improvement of over 47% in the PSCs with the introduction of the TiO2-AuNPs_MDA on the ETL/MAPI interface compared to the reference device. Our study demonstrates the significant enhancement achieved in halide PSC by utilizing AuNPs within a TiO2_MDA. This approach holds great promise for advancing the efficiency and performance of photovoltaic devices.

Plasmonic enhancement of photovoltaic characteristics of organic solar cells by employing parabola nanostructures at the back of the solar cell

In this paper, we demonstrate the enhanced performance of organic solar cells (OSCs) comprising low band gap photoactive layers (PMDPP3T:PC70BM) and 2-dimensional (2D) arrays of either Ag nano-spheres, nano-hemispheres, or nano-parabolas embedded at the back of the OSCs. Finite-difference time-domain (FDTD) simulations were performed to compare the performance of the OSCs containing the different plasmonic nanostructures, in terms of optical absorption, short circuit current density (JSC) and power conversion efficiency (PCE). The results demonstrate that single junction OSCs consisting of this new active layer polymer (PMDPP3T), blended with PC70BM, and plasmonic nanostructures at the back of the OSC can enhance the optical absorption in the visible and the NIR region. We demonstrate that the aspect ratio of the nanoparticles embedded at the back of OSCs is a vital parameter for light absorption enhancement. It is observed that the performance in terms of JSC and PCE enhancement of OSC having 2D arrays of Ag nano-parabola at the back of the solar cell improved by 26.41% and 26.37%, respectively, compared to a planar OSC. The enhancement in photon absorption can be attributed due to the enhancement of light scattering from metallic nanostructures near their localized plasmon resonance.

Advances in the Application of Perovskite Materials

Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices (solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices (artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.

Micro-patterns of gold nanoparticles assembled by photovoltaic optoelectronic tweezers: application to plasmonic fluorescence enhancement

Noble metal nanostructures are well-known for their ability to increase the efficiency of different optical or physical phenomena due to their plasmonic behavior. This work presents a simple strategy to obtain Au plasmonic patterns by optically induced nanoparticle assembly and its application as fluorescence enhancement platforms. This strategy is based on the so-called photovoltaic optoelectronic tweezers (PVOT) being the first time they are used for fabricating Au periodic micro-patterns. Fringe patterns with a sub-structure of aggregates, assembled from individual spherical nanoparticles of 3.5 or 170 nm diameters, are successfully obtained. The spatial distribution of the aggregates is controlled with micrometric accuracy and the patterns can be arranged over large-scale active areas (tens of mm²). The outcome for the ultra-small (3.5 nm) particles is particularly relevant because this diameter is the smallest one manipulated by PVOT so far. Testing experiments of plasmonic fluorescence enhancement show that the 170-nm patterns present a much better plasmonic behavior. For the 170-nm platform they reveal a 10-fold enhancement factor in the fluorescence of Rhodamine-B dye molecules and a 3-fold one for tagged DNA biomolecules. Hence, the results suggest that these latter plasmonic platforms are good candidates for efficient bio-imaging and biosensing techniques, among other applications.

Broad-Band-Enhanced Plasmonic Perovskite Solar Cells with Irregular Silver Nanomaterials

The localized surface plasmon resonance (LSPR) from noble metal nanomaterials (NMs) is a promising solution to approach the theoretical efficiency for photovoltaic devices. However, the plasmon resonance of metal NMs with particular shapes and sizes can only be excited within narrow spectral ranges, which can hardly cover the broad-band solar spectrum. To address this issue, in this article, Ag NMs with irregular shapes and sizes are synthesized and embedded in the electron transport layer of perovskite solar cells. With the outstanding conductivity of Ag NMs, the series resistance and charge transfer resistance of the devices are dramatically decreased. The Ag NMs with larger size could enhance the light-trapping of the devices owing to the far-field light scattering effect. The near-field enhancement by LSPR of Ag NMs with a small size mainly contributes to the promotion of carrier transport and extraction. As a result, broad-band improvements in photovoltaic performance are achieved due to the significant enhancement of light absorption and electrical features. The highest power conversion efficiency of the perovskite solar cells increases from 19.52 to 22.42% after the incorporation of Ag NMs.

Azadipyrromethene Dye-Assisted Defect Passivation for Efficient and Stable Perovskite Solar Cells

Organic-inorganic perovskite solar cells (PSCs) provide one of the most outstanding photovoltaic (PV) technologies, yet their efficiency, stability, and defect passivation engineering still remain challenging. We demonstrate the use of low-cost, eco-friendly, and multi-functional aza-dipyrromethene (Aza-DIPY) dye molecules to promote the power conversion efficiency (PCE) and the operating stability of PSC devices. The Aza-DIPY dye was meticulously synthesized and incorporated into PSC devices via a one-step solution processing approach. The pyrrole, benzene ring, and chlorine functional groups on the dye have intense interactions with perovskite to passivate surface defects and obtain high-quality perovskite absorbers, resulting in the lengthened carrier recombination time and enhanced fill factor of PSCs. Additionally, the hydrophobic phenyl and halogen functional groups on the Aza-DIPY perform as a protecting barrier against moisture and ameliorate the stability of PSCs. As a consequence, the PV performance of PSCs is considerably improved, with the average PCE increased from 16.71% to 19.71%, and the champion device with Aza-DIPY shows a PCE of 20.46%. The unencapsulated PSC devices with multi-functional molecular Aza-DIPY maintains 89.06% of their beginning PCEs after storage in ambient air (25-30 °C, 50-70% relative humidity) under dark conditions for 100 h, exhibiting a significantly enhanced ambient stability compared with the case of the reference cells without the dye. Furthermore, the Aza-DIPY-modified PSC devices exhibit strong and reversible photoresponses, with a high responsivity of 0.739 mA/W to near-infrared (NIR) laser beams. Our results highlight the potential of synthesizing multi-functional Aza-DIPY dyes-incorporated PSC devices with sensitive NIR/visible light responses, high PV efficiency, and stability.

Luminescence enhancement effects on nanostructured perovskite thin films for Er/Yb-doped solar cells

Recent attempts to improve solar cell performance by increasing their spectral absorption interval incorporate up-converting fluorescent nanocrystals on the structure. These nanocrystals absorb low energy light and emit higher energy photons that can then be captured by the solar cell active layer. However, this process is very inefficient and it needs to be enhanced by different strategies. In this work, we have studied the effect of nanostructuration of perovskite thin films used in the fabrication of hybrid solar cells on their local optical properties. The perovskite surface was engraved with a focused ion beam to form gratings of one-dimensional grooves. We characterized the surfaces with a fluorescence scanning near-field optical microscope, and obtained maps showing a fringe pattern oriented in a direction parallel to the grooves. By scanning structures as a function of the groove depth, ranging from 100 nm to 200 nm, we observed that a 3-fold luminescence enhancement could be obtained for the deeper ones. Near-field luminescence was found to be enhanced between the grooves, not inside them, independent of the groove depth and the incident polarization direction. This indicates that the ideal position of the nanocrystals is between the grooves. In addition, we also studied the influence of the inhomogeneities of the perovskite layer and we observed that roughness tends to locally modify the intensity of the fringes and distort their alignment. All the experimental results are in good agreement with numerical simulations.

Research Progress of Plasmonic Nanostructure-Enhanced Photovoltaic Solar Cells

Enhancement of the electromagnetic properties of metallic nanostructures constitute an extensive research field related to plasmonics. The latter term is derived from plasmons, which are quanta corresponding to longitudinal waves that are propagating in matter by the collective motion of electrons. Plasmonics are increasingly finding wide application in sensing, microscopy, optical communications, biophotonics, and light trapping enhancement for solar energy conversion. Although the plasmonics field has relatively a short history of development, it has led to substantial advancement in enhancing the absorption of the solar spectrum and charge carrier separation efficiency. Recently, huge developments have been made in understanding the basic parameters and mechanisms governing the application of plasmonics, including the effects of nanoparticles' size, arrangement, and geometry and how all these factors impact the dielectric field in the surrounding medium of the plasmons. This review article emphasizes recent developments, fundamentals, and fabrication techniques for plasmonic nanostructures while investigating their thermal effects and detailing light-trapping enhancement mechanisms. The mismatch effect of the front and back light grating for optimum light trapping is also discussed. Different arrangements of plasmonic nanostructures in photovoltaics for efficiency enhancement, plasmonics' limitations, and modeling performance are also deeply explored.

Plasmonic-perovskite solar cells, light emitters, and sensors

The field of plasmonics explores the interaction between light and metallic micro/nanostructures and films. The collective oscillation of free electrons on metallic surfaces enables subwavelength optical confinement and enhanced light-matter interactions. In optoelectronics, perovskite materials are particularly attractive due to their excellent absorption, emission, and carrier transport properties, which lead to the improved performance of solar cells, light-emitting diodes (LEDs), lasers, photodetectors, and sensors. When perovskite materials are coupled with plasmonic structures, the device performance significantly improves owing to strong near-field and far-field optical enhancements, as well as the plasmoelectric effect. Here, we review recent theoretical and experimental works on plasmonic perovskite solar cells, light emitters, and sensors. The underlying physical mechanisms, design routes, device performances, and optimization strategies are summarized. This review also lays out challenges and future directions for the plasmonic perovskite research field toward next-generation optoelectronic technologies.

Bio-inspired strategies for next-generation perovskite solar mobile power sources

Smart electronic devices are becoming ubiquitous due to many appealing attributes including portability, long operational time, rechargeability and compatibility with the user-desired form factor. Integration of mobile power sources (MPS) based on photovoltaic technologies with smart electronics will continue to drive improved sustainability and independence. With high efficiency, low cost, flexibility and lightweight features, halide perovskite photovoltaics have become promising candidates for MPS. Realization of these photovoltaic MPS (PV-MPS) with unconventionally extraordinary attributes requires new 'out-of-box' designs. Natural materials have provided promising designing solutions to engineer properties under a broad range of boundary conditions, ranging from molecules, proteins, cells, tissues, apparatus to systems in animals, plants, and humans optimized through billions of years of evolution. Applying bio-inspired strategies in PV-MPS could be biomolecular modification on crystallization at the atomic/meso-scale, bio-structural duplication at the device/system level and bio-mimicking at the functional level to render efficient charge delivery, energy transport/utilization, as well as stronger resistance against environmental stimuli (e.g., self-healing and self-cleaning). In this review, we discuss the bio-inspired/-mimetic structures, experimental models, and working principles, with the goal of revealing physics and bio-microstructures relevant for PV-MPS. Here the emphasis is on identifying the strategies and material designs towards improvement of the performance of emerging halide perovskite PVs and strategizing their bridge to future MPS.

Light absorption enhancement in ultrathin perovskite solar cells using light scattering of high-index dielectric nanospheres

Arrays of high-index dielectric nanoparticles supporting both electrical and magnetic resonances have gained increasing attention for their excellent light-trapping (LT) effects, thus greatly improving the performance of ultrathin solar cells. This work explores front-located, high-index dielectric subwavelength nanosphere arrays as an efficient and broadband LT structure patterned on top of an ultrathin perovskite solar cell (PSC) for a greatly enhanced absorption. Combined strong light scattering and anti-reflection properties achieved by optimized geometrical parameters of the LT structure lead to a broadband absorption enhancement in the ultrathin thickness of a photoactive layer (100 nm) yielding the short-circuit current density (Jsc) of 18.7 mA/cm², which is 31.7% higher than that of a planar counterpart. Moreover, effects of the LT structure on far-field radiation patterns, scattering cross-sections, multipoles' contributions, and asymmetry parameters along with the incidence angle and polarization dependence are investigated. The present strategy could be applied to diverse applications, such as other ultrathin or semitransparent solar cells, absorbers and photodetectors.

Ag/MgO Nanoparticles via Gas Aggregation Nanocluster Source for Perovskite Solar Cell Engineering

Nanocluster aggregation sources based on magnetron-sputtering represent precise and versatile means to deposit a controlled quantity of metal nanoparticles at selected interfaces. In this work, we exploit this methodology to produce Ag/MgO nanoparticles (NPs) and deposit them on a glass/FTO/TiO₂ substrate, which constitutes the mesoscopic front electrode of a monolithic perovskite-based solar cell (PSC). Herein, the Ag NP growth through magnetron sputtering and gas aggregation, subsequently covered with MgO ultrathin layers, is fully characterized in terms of structural and morphological properties while thermal stability and endurance against air-induced oxidation are demonstrated in accordance with PSC manufacturing processes. Finally, once the NP coverage is optimized, the Ag/MgO engineered PSCs demonstrate an overall increase of 5% in terms of device power conversion efficiencies (up to 17.8%).

Oxide and Organic–Inorganic Halide Perovskites with Plasmonics for Optoelectronic and Energy Applications: A Contributive Review

The ascension of halide perovskites as outstanding materials for a wide variety of optoelectronic applications has been reported in recent years. They have shown significant potential for the next generation of photovoltaics in particular, with a power conversion efficiency of 25.6% already achieved. On the other hand, oxide perovskites have a longer history and are considered as key elements in many technological applications; they have been examined in depth and applied in various fields, owing to their exceptional variability in terms of compositions and structures, leading to a large set of unique physical and chemical properties. As of today, a sound correlation between these two important material families is still missing, and this contributive review aims to fill this gap. We report a detailed analysis of the main functions and properties of oxide and organic–inorganic halide perovskite, emphasizing existing relationships amongst the specific performance and the structures.

Photon management to reduce energy loss in perovskite solar cells

Despite the rapid development of perovskite solar cells (PSCs) over the past few years, the conversion of solar energy into electricity is not efficient enough or cost-competitive yet. The principal energy loss in the conversion of solar energy to electricity fundamentally originates from the non-absorption of low-energy photons ascribed to Shockley-Queisser limits and thermalization losses of high-energy photons. Enhancing the light-harvesting efficiency of the perovskite photoactive layer by developing efficient photo management strategies with functional materials and arrays remains a long-standing challenge. Here, we briefly review the historical research trials and future research trends to overcome the fundamental loss mechanisms in PSCs, including upconversion, downconversion, scattering, tandem/graded structures, texturing, anti-reflection, and luminescent solar concentrators. We will deeply emphasize the availability and analyze the importance of a fine device structure, fluorescence efficiency, material proportion, and integration position for performance improvement. The unique energy level structure arising from the 4fn inner shell configuration of the trivalent rare-earth ions gives multifarious options for efficient light-harvesting by upconversion and downconversion. Tandem or graded PSCs by combining a series of subcells with varying bandgaps seek to rectify the spectral mismatch. Plasmonic nanostructures function as a secondary light source to augment the light-trapping within the perovskite layer and carrier transporting layer, enabling enhanced carrier generation. Texturing the interior using controllable micro/nanoarrays can realize light-matter interactions. Anti-reflective coatings on the top glass cover of the PSCs bring about better transmission and glare reduction. Photon concentration through perovskite-based luminescent solar concentrators offers a path to increase efficiency at reduced cost and plays a role in building-integrated photovoltaics. Distinct from other published reviews, we here systematically and hierarchically present all of the photon management strategies in PSCs by presenting the theoretical possibilities and summarizing the experimental results, expecting to inspire future research in the field of photovoltaics, phototransistors, photoelectrochemical sensors, photocatalysis, and especially light-emitting diodes. We further assess the overall possibilities of the strategies based on ultimate efficiency prospects, material requirements, and developmental outlook.

Influence of Ag@SiO2 with Different Shell Thickness on Photoelectric Properties of Hole-Conductor-Free Perovskite Solar Cells

In this paper, Ag@SiO2 core-shell nanoparticles (NPs) with different shell thicknesses were prepared experimentally and introduced into the photosensitive layer of mesoscopic hole-conductor-free perovskite solar cells (PSCs) based on carbon counter electrodes. By combining simulation and experiments, the influences of different shell thickness Ag@SiO2 core-shell nanoparticles on the photoelectric properties of the PSCs were studied. The results show that, when the shell thickness of 0.1 wt% Ag@SiO2 core-shell nanoparticles is 5 nm, power conversion efficiency is improved from 13.13% to 15.25%, achieving a 16% enhancement. Through the measurement of the relevant parameters of the obtained perovskite film, we found that this gain not only comes from the increase in current density that scholars generally think, but also comes from the improvement of the film quality. Like current gain, this gain is related to the different shell thickness of Ag@SiO2 core-shell nanoparticles. Our research provides a new direction for studying the influence mechanism of Ag@SiO2 core-shell nanoparticles in perovskite solar cells.

Enhanced Efficiency and Stability of Planar Perovskite Solar Cells Using a Dual Electron Transport Layer of Gold Nanoparticles Embedded in Anatase TiO2 Films

Incorporating plasmonic nanostructures is a promising strategy to enhance both the optical and electrical characteristics of photovoltaic devices via more efficient harvesting of incident light. Herein, we report a facile fabrication scheme at low temperature for producing gold nanoparticles embedded in anatase TiO₂ films, which can simultaneously improve the efficiency and stability of n-i-p planar heterojunction perovskite solar cells (PSCs). The PSCs based on rigid and flexible substrates with 0.2 wt % Au-TiO₂/TiO₂ dual electron transport layers (ETLs) achieved power conversion efficiencies up to 20.31 and 15.36%, superior to that of devices with TiO₂ as a single ETL. Moreover, 0.2 wt % Au-TiO₂/TiO₂ devices demonstrated significant stability in light soaking, which is attributed to improved light absorption, low charge recombination loss, and enhanced carrier transport, and extraction with the plasmonic Au-TiO₂/TiO₂ dual ETL. The present work improves the practicability of high-performance and flexible PSCs by engineering the photogenerated carrier dynamics at the interface.

Synergetic Effect of Plasmonic Gold Nanorods and MgO for Perovskite Solar Cells

We report new structured perovskite solar cells (PSCs) using solution-processed TiO₂/Au nanorods/MgO composite electron transport layers (ETLs). The proposed method is facile, convenient, and effective. Briefly, Au nanorods (NRs) were prepared and introduced into mesoporous TiO₂ ETLs. Then, thin MgO overlayers were grown on the Au NRs modified ETLs by wet spinning and pyrolysis of the magnesium salt. By simultaneous use of Au NRs and MgO, the power conversion efficiency of the PSC device increases from 14.7% to 17.4%, displaying over 18.3% enhancement, compared with the reference device without modification. Due to longitudinal plasmon resonances (LPRs) of gold nanorods, the embedded Au NRs exhibit the ability to significantly enhance the near-field and far-field (plasmonic scattering), increase the optical path length of incident photons in the device, and as a consequence, notably improve external quantum efficiency (EQE) at wavelengths above 600 nm and power conversion efficiency (PCE) of PSC solar cells. Meanwhile, the thin MgO overlayer also contributes to enhanced performance by reducing charge recombination in the solar cell. Theoretical calculations were carried out to elucidate the PV performance enhancement mechanisms.

TiO2 Nanocolumn Arrays for More Efficient and Stable Perovskite Solar Cells

Organic-inorganic hybrid perovskite solar cells have attracted much attention due to their high power conversion efficiency (>25%) and low-cost fabrication. Yet, improvements are still needed for more stable and higher-performing solar cells. In this work, a series of TiO₂ nanocolumn photonic structures have been intentionally fabricated on half of the compact TiO₂-coated fluorine-doped tin oxide substrate by glancing angle deposition with magnetron sputtering, a method particularly suitable for industrial applications due to its high reliability and reduced cost when coating large areas. These vertically aligned nanocolumn arrays were then applied as the electron transport layer into triple-cation lead halide perovskite solar cells based on Cs_0.05(FA_0.83MA_0.17)_0.95Pb(I_0.83Br_0.17)₃. By comparison to solar cells built onto the same substrate without nanocolumns, the use of TiO₂ nanocolumns can significantly enhance the power conversion efficiency of the perovskite solar cells by 7% and prolong their shelf life. Here, detailed characterizations on the morphology and the spectroscopic aspects of the nanocolumns, their near-field and far-field optical properties, solar cells characteristics, as well as the charge transport properties provide mechanistic insights on how one-dimensional TiO₂ nanocolumns affect the performance of perovskite halide solar cells in terms of charge transport, light harvesting, and stability, knowledge necessary for the future design of higher-performing and more stable perovskite solar cells.

Optical-electrical-thermal optimization of plasmon-enhanced perovskite solar cells

We established an optical-electrical-thermal model that improves the electrical properties of PSCs.

High performance perovskite solar cells using Cu9S5 supraparticles incorporated hole transport layers

We disclose novel photovoltaic device physics and present details of device mechanisms by investigating perovskite solar cells (PSCs) incorporating Cu₉S₅@SiO₂ supraparticles (SUPs) into Spiro-OMeTAD based hole transport layers (HTLs). High quality colloidal Cu₉S₅ nanocrystals (NCs) were prepared using a hot-injection approach. Multiple Cu₉S₅ NCs were further embedded in silica to construct a Cu₉S₅@SiO₂ SUP. Cu₉S₅@SiO₂ SUPs were blended into Spiro-OMeTAD based HTLs with different weight ratios. Theoretical and experimental results show that the very strong light scattering or reflecting properties of Cu₉S₅@SiO₂ SUPs blended in the PSC device in a proper proportion distribute to increase the light energy trapped within the device, leading to significant enhancement of light absorption in the active layer. Additionally, the incorporated Cu₉S₅@SiO₂ SUPs can also promote the electrical conductivity and hole-transport capacity of the HTL. Significantly larger conductivity and higher hole injection efficiency were demonstrated in the HTM with the optimal weight ratios of Cu₉S₅@SiO₂ SUPs. As a result, efficient Cu₉S₅ SUPs based PSC devices were obtained with average power conversion efficiency (PCE) of 18.21% at an optimal weight ratio of Cu₉S₅ SUPs. Compared with PSC solar cells without Cu₉S₅@SiO₂ SUPs (of which the average PCE is 14.38%), a remarkable enhancement over 26% in average PCE was achieved. This study provides an innovative approach to efficiently promote the performance of PSC devices by employing optically stable, low-cost and green p-type semiconductor SUPs.

Tandem organic solar cells containing plasmonic nanospheres and nanostars for enhancement in short circuit current density

In this paper, we propose double junction tandem organic solar cells with PTB7:PC₇₀BM and PDPPSDTPS:PC₆₀BM as the polymeric active materials to cover the wide solar spectrum from 300 nm to 1150 nm. We present novel designs and finite-difference time-domain (FDTD) simulation results of plasmonic double junction tandem OSCs in which Ag nanospheres are present over the top surface of the OSC and Ag nanostars are present in the bottom subcell which substantially enhance the absorption, short circuit current density, and efficiency of the OSC as compared to the reference tandem OSCs that do not contain any nanoparticles. Different geometries of the plasmonic nanoparticles such as nanospheres and nanostars were used in the top subcell and the bottom subcell, respectively, so that the absorption in the different spectral regimes - corresponding to the bandgaps of the active layers in the two subcells (PTB7:PC₇₀BM in the top subcell and LBG:PC₆₀BM in the bottom subcell) - could be enhanced. The thickness of the bottom subcell active layer as well as the geometries of the plasmonic nanoparticles were optimized such that the short circuit current densities in the two subcells could be matched in the tandem OSC. An overall enhancement of 26% in the short circuit current density was achieved in a tandem OSC containing the optimized Ag nanospheres over the top surface and Ag nanostars inside the bottom subcell active layer. The presence of plasmonic nanoparticles along with the wide spectrum absorption band of the active materials in the tandem OSC leads to a typical power conversion efficiency of ∼ 15.4%, which is higher than that of a reference tandem organic solar cell (12.25%) that does not contain any nanoparticles.

Broadband Solar Energy Absorption in Plasmonic Thin-Film Amorphous Silicon Solar Cell

Improving the light absorption in thin-film solar cell is essential for enhancing efficiency and reducing cost. Here, we propose an ultra-broadband amorphous silicon solar cell based on a periodic array of titanium ring-shaped metasurfaces, which achieves more than 90% absorptance in the visible range of the solar spectrum. The surface plasmon resonance supported by the nanoparticles together with the resonance induced by the metal–insulator–metal Fabry–Perot cavity leads to this broadband absorption. The impact of various materials of functional layers and the geometric structure of the nanoparticle on absorption performance is discussed in detail, and super broadband resonance is achieved after optimization. Moreover, the optimized solar cell is tested for different solar incidence angles and it is found that the structure exhibits high absorption efficiency even at large angles. Thus, the proposed solar cell design may be beneficial for most of the photovoltaic applications.

The Influence of Embedded Plasmonic Nanostructures on the Optical Absorption of Perovskite Solar Cells

The interaction of light with plasmonic nanostructures can induce electric field intensity either around or at the surface of the nanostructures. The enhanced intensity of the electric field can increase the probability of light absorption in the active layer of solar cells. The absorption edge of perovskite solar cells (PSCs), which is almost 800 nm, can be raised to higher wavelengths with the help of plasmonic nanostructures due to their perfect photovoltaic characteristics. We placed plasmonic nanoparticles (NPs) with different radii (20–60 nm) within the bulk of the perovskite solar cell and found that the Au nanoparticles with a radius of 60 nm increased the absorption of the cell by 20% compared to the bare one without Au nanoparticles. By increasing the radius of the nanoparticles, the total absorption of the cell will increase because of the scattering enhancement. The results reveal that the best case is the PSC with the NP radius of 60 nm.

Using a Neural Network to Improve the Optical Absorption in Halide Perovskite Layers Containing Core-Shells Silver Nanoparticles

Core-shells metallic nanoparticles have the advantage of possessing two plasmon resonances, one in the visible and one in the infrared part of the spectrum. This special property is used in this work to enhance the efficiency of thin film solar cells by improving the optical absorption at both wavelength ranges simultaneously by using a neural network. Although many thin-film solar cell compositions can benefit from such a design, in this work, different silver core-shell configurations were explored inside a Halide Perovskite (CH₃NH₃PbI₃) thin film. Because the number of potential configurations is infinite, only a limited number of finite difference time domain (FDTD) simulations were performed. A neural network was then trained with the simulation results to find the core-shells configurations with optimal optical absorption across different wavelength ranges. This demonstrates that core-shells nanoparticles can make an important contribution to improving solar cell performance and that neural networks can be used to find optimal results in such nanophotonic systems.

The optimization of methods of synthesis of nickel-silver core-shell nanoparticles for conductive materials

Nickel-silver core-shell (Ni@Ag) nanoparticles (NPs) were formed in a two-step process: (1) the formation of a dispersion of Ni NPs; and (2) the transmetalation (galvanic displacement) reaction, where the surface of the Ni NPs acted as the reducing agent of Ag ions. Ni NPs were synthesized by the 'wet' chemical method, i.e., by the reduction of metal ions by using NaBH₄ as the reducing agent. The influence of the concentration of polymeric stabilizer, reducing agent and Ag precursor on the properties of synthesized NPs was evaluated. In the optimal condition of synthesis, Ni@Ag NPs with about 50 and 210 nm-diameter Ni core coated with a thin (∼10-20 nm) Ag shell, were obtained. Finally, the stability of the synthesized spherical-shaped Ni@Ag NPs was tested and the results indicate long-term stability against aggregation and Ni oxidation. Thus, the resulting NPs are promising candidates for application in electronic devices, e.g., as components of conductive inks or pastes.

Super absorption of solar energy using a plasmonic nanoparticle based CdTe solar cell

Improving the photon absorption in thin-film solar cells with plasmonic nanoparticles is essential for the realization of extremely efficient cells with substantial cost reduction.

Ag@SiO₂ Core-shell Nanoparticles Embedded in a TiO₂ Mesoporous Layer Substantially Improve the Performance of Perovskite Solar Cells

In this study, Ag@SiO₂ nanoparticles were synthesized by a modified Stöber method for preparing the TiO₂ mesoporous layer of carbon counter electrode-based perovskite solar cells (PSCs) without a hole transporting layer. Compared with normal PSCs (without Ag@SiO₂ incorporated in the TiO₂ mesoporous layer), PSCs with an optimal content of Ag@SiO₂ (0.3 wt. % Ag@SiO₂-TiO₂) show a 19.46% increase in their power conversion efficiency, from 12.23% to 14.61%, which is mainly attributed to the 13.89% enhancement of the short-circuit current density, from 20.23 mA/cm² to 23.04 mA/cm². These enhancements mainly contributed to the localized surface Plasmon resonance effect and the strong scattering effect of Ag@SiO₂ nanoparticles. However, increasing the Ag@SiO₂ concentration in the mesoporous layer past the optimum level cannot further increase the short-circuit current density and incident photon-to-electron conversion efficiency of the devices, which is primarily ascribed to the electron transport pathways being impeded by the insulating silica shells inside the TiO₂ network.

Influence of Ag Nanoparticles with Different Sizes and Concentrations Embedded in a TiO2 Compact Layer on the Conversion Efficiency of Perovskite Solar Cells

In this study, Ag nanoparticles with diverse particle size and concentration, fabricated via the polyol method, were embedded in a TiO2 compact film to improve the power conversion efficiency of perovskite solar cells. Obtained results showed that Ag nanoparticles embedded in the TiO2 compact film do not affect the crystal structure of TiO2, while the size of the Ag nanoparticles can strongly influence the light absorption capacity of perovskite materials. However, the absorption intensity and power conversion efficiency of perovskite cells decreased with the increase in size of Ag nanoparticles. The amount of Ag nanoparticles was also an important factor for the performance of perovskite solar cells, and Ag nanoparticles in the compact layer were optimized to measure 10 nm in diameter, being embedded at a molar ratio of 1.5% (Ag:Ti = 1.5 mol%). Compared with hole-conductor-free perovskite solar cells that use carbon as counter electrodes, without Ag nanoparticles incorporated in the compact film, the enhanced efficiency of cells developed in this study can be mainly ascribed to the accelerated charge transfer, decreased charge recombination, and enhanced light absorption of the perovskite material in the visible region.