Special Issue "Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Synthesis, Interfaces and Nanostructures".

Deadline for manuscript submissions: closed (31 July 2021).

Special Issue Editor

Dr. Alessandra Alberti
E-Mail Website
Guest Editor
Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Catania, Italy
Interests: hybrid and inorganic photoactive perovskites; metal oxides; interfaces; structural dynamics of interacting materials; sputtering deposition and evaporation; X-ray analyses

Special Issue Information

Dear Colleagues, 

Hybrid photovoltaics (H-PV), initiated as dye-sensitized solar cells (DSCs) and further extended as perovskite solar cells (PSCs), have been revolutionizing perspectives with their high efficiency that is approaching that of silicon-based counterparts. The technological breakthrough resides, on one hand, in a cost-efficiency convenience and, on the other hand, in the perspective of overcoming the Shockley–Queisser limit for single solar cells if PSCs are combined in tandem architectures. Together with outdoor PV, dedicated hybrid solar cell technologies for indoor powering and aerospace are under the spotlight.

In this highly encouraging framework, materials science has been playing a major role with the pivotal involvement of mesoporous materials and nanoscale phenomena that take place in the layers and many interfaces established through the layered architecture of DSCs and PSCs.

This Special Issue of Nanomaterials welcomes contributions concerning the challenges facing the H-PV field in the growth/synthesis, functionalization, interfacing, light absorption, carrier generation and injection, stabilization, and integration of materials in DSCs and PSCs architectures, with a special focus on mesoscale behavior and nanoscale phenomena. The list of materials includes metal oxides and molecular layers for carrier extraction, transparent and conductive oxides, photoactive molecules, and additives, encapsulating hydrophobic materials and photoactive perovskites. Mesostructured layers, engineered molecules, 2D and 3D perovskites, as well as blended materials with their functionalities, active interfaces, defects, structures, and operational behavior are of particular relevance for this Special Issue. The aim of the issue is to increase our knowledge of the properties and behavior of single and combined materials for hybrid photovoltaics that can help improve their structural, optical, and electrical performances considering their implementation in devices.

Dr. Alessandra Alberti
Guest Editor

Manuscript Submission Information

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Keywords

  • DSCs and PSCs
  • Mesoporous scaffolds
  • Innovative growth methods
  • 3D, 2D, 1D, and nanosized photoactive perovskites
  • Bandgap engineering of perovskites
  • Electron- and hole-transporting materials and molecules
  • Solid/solid and solid/liquid interfaces for efficient charge extraction
  • Defects formation and aggregation
  • Material stability issues and remedies
  • Device operational issues and remedies
  • Encapsulating layers and sealants
  • Conventional and innovative transparent conductive oxides
  • Newly designed photoactive molecules and non-liquid electrolytes
  • Theoretical modeling of materials for DSCs and PSCs

Published Papers (8 papers)

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Research

Article
Optimized Stoichiometry for CuCrO2 Thin Films as Hole Transparent Layer in PBDD4T-2F:PC70BM Organic Solar Cells
Nanomaterials 2021, 11(8), 2109; https://doi.org/10.3390/nano11082109 - 19 Aug 2021
Viewed by 601
Abstract
The performance and stability in atmospheric conditions of organic photovoltaic devices can be improved by the integration of stable and efficient photoactive materials as substituent of the chemically unstable poly (3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS), generally used as organic hole transport layer. Promising candidates [...] Read more.
The performance and stability in atmospheric conditions of organic photovoltaic devices can be improved by the integration of stable and efficient photoactive materials as substituent of the chemically unstable poly (3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS), generally used as organic hole transport layer. Promising candidates are p-type transparent conductive oxides, which combine good optoelectronic and a higher mechanical and chemical stability than the organic counterpart. In this work, we synthesize Cu-rich CuCrO2 thin films by aerosol-assisted chemical vapour deposition as an efficient alternative to PEDOT:PSS. The effect of stoichiometry on the structural, electrical, and optical properties was analysed to find a good compromise between transparency, resistivity, and energy bands alignment, to maximize the photovoltaic performances., Average transmittance and bandgap are reduced when increasing the Cu content in these out of stoichiometry CuCrO2 films. The lowest electrical resistivity is found for samples synthesized from a solution composition in the 60–70% range. The optimal starting solution composition was found at 65% of Cu cationic ratio corresponding to a singular point in Hackee’s figure of merit of 1 × 10−7−1. PBDD4T-2F:PC70BM organic solar cells were fabricated by integrating CuCrO2 films grown from a solution composition ranging between 40% to 100% of Cu as hole transport layers. The solar cells integrating a film grown with a Cu solution composition of 65% achieved a power conversion efficiency as high as 3.1%, representing the best trade-off of the optoelectronic properties among the studied candidates. Additionally, despite the efficiencies achieved from CuCrO2-based organic solar cells are still inferior to the PEDOT:PSS counterpart, we demonstrated a significant enhancement of the lifetime in atmospheric conditions of optimal oxides-based organic photovoltaic devices. Full article
(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)
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Article
Inclusion of 2D Transition Metal Dichalcogenides in Perovskite Inks and Their Influence on Solar Cell Performance
Nanomaterials 2021, 11(7), 1706; https://doi.org/10.3390/nano11071706 - 29 Jun 2021
Viewed by 739
Abstract
Organic–inorganic hybrid perovskite materials have raised great interest in recent years due to their excellent optoelectronic properties, which promise stunning improvements in photovoltaic technologies. Moreover, two-dimensional layered materials such as graphene, its derivatives, and transition metal dichalcogenides have been extensively investigated for a [...] Read more.
Organic–inorganic hybrid perovskite materials have raised great interest in recent years due to their excellent optoelectronic properties, which promise stunning improvements in photovoltaic technologies. Moreover, two-dimensional layered materials such as graphene, its derivatives, and transition metal dichalcogenides have been extensively investigated for a wide range of electronic and optoelectronic applications and have recently shown a synergistic effect in combination with hybrid perovskite materials. Here, we report on the inclusion of liquid-phase exfoliated molybdenum disulfide nanosheets into different perovskite precursor solutions, exploring their influence on final device performance. We compared the effect of such additives upon the growth of diverse perovskites, namely CH3NH3PbI3 (MAPbI3) and triple-cation with mixed halides Csx (MA0.17FA0.83)(1−x)Pb (I0.83Br0.17)3 perovskite. We show how for the referential MAPbI3 materials the addition of the MoS2 additive leads to the formation of larger, highly crystalline grains, which result in a remarkable 15% relative improvement in power conversion efficiency. On the other hand, for the mixed cation–halide perovskite no improvements were observed, confirming that the nucleation process for the two materials is differently influenced by the presence of MoS2. Full article
(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)
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Article
Structural Transitions and Stability of FAPbI3 and MAPbI3: The Role of Interstitial Water
Nanomaterials 2021, 11(6), 1610; https://doi.org/10.3390/nano11061610 - 18 Jun 2021
Viewed by 763
Abstract
We studied the influence of water on the structural stability and transformations of MAPI and FAPI by anelastic and dielectric spectroscopies under various temperature and H2O partial pressure protocols. Before discussing the new results in terms of interstitial water in MAPI [...] Read more.
We studied the influence of water on the structural stability and transformations of MAPI and FAPI by anelastic and dielectric spectroscopies under various temperature and H2O partial pressure protocols. Before discussing the new results in terms of interstitial water in MAPI and FAPI, the literature is briefly reviewed, in search of other studies and evidences on interstitial water in hybrid halide perovskites. In hydrated MAPI, the elastic anomaly between the cubic α and tetragonal β phases may be depressed by more than 50%, demonstrating that there are H2O molecules dispersed in the perovskite lattice in interstitial form, that hinder the long range tilting of the PbI6 octahedra. Instead, in FAPI, interstitial water accelerates in both senses the reconstructive transformations between 3D α and 1D δ phases, which is useful during the crystallization of the α phase. On the other hand, the interstitial H2O molecules increase the effective size of the MA and FA cations to which are bonded, shifting the thermodynamic equilibrium from the compact perovskite structure to the open δ and hydrated phases of loosely bonded chains of PbI6 octahedra. For this reason, when fabricating devices based on hybrid metal-organic halide perovskites, it is important to reduce the content of interstitial water as much as possible before encapsulation. Full article
(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)
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Article
Exploring the Structural Competition between the Black and the Yellow Phase of CsPbI3
Nanomaterials 2021, 11(5), 1282; https://doi.org/10.3390/nano11051282 - 13 May 2021
Cited by 1 | Viewed by 776
Abstract
The realization of stable inorganic perovskites is crucial to enable low-cost solution-processed photovoltaics. However, the main candidate material, CsPbI3, suffers from a spontaneous phase transition at room temperature towards a photo-inactive orthorhombic δ-phase (yellow phase). Here we used theoretical and experimental [...] Read more.
The realization of stable inorganic perovskites is crucial to enable low-cost solution-processed photovoltaics. However, the main candidate material, CsPbI3, suffers from a spontaneous phase transition at room temperature towards a photo-inactive orthorhombic δ-phase (yellow phase). Here we used theoretical and experimental methods to study the structural and electronic features that determine the stability of the CsPbI3 perovskite. We argued that the two physical characteristics that favor the black perovskite phase at low temperatures are the strong spatial confinement in nanocrystalline structures and the level of electron doping in the material. Within this context, we discussed practical procedures for the realization of long-lasting inorganic lead halide perovskites. Full article
(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)
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Article
In Situ Raman Microdroplet Spectroelectrochemical Investigation of CuSCN Electrodeposited on Different Substrates
Nanomaterials 2021, 11(5), 1256; https://doi.org/10.3390/nano11051256 - 11 May 2021
Cited by 1 | Viewed by 557
Abstract
Systematic in situ Raman microdroplet spectroelectrochemical (Raman-μSEC) characterization of copper (I) thiocyanate (CuSCN) prepared using electrodeposition from aqueous solution on various substrates (carbon-based, F-doped SnO2) is presented. CuSCN is a promising solid p-type inorganic semiconductor used in perovskite solar cells as [...] Read more.
Systematic in situ Raman microdroplet spectroelectrochemical (Raman-μSEC) characterization of copper (I) thiocyanate (CuSCN) prepared using electrodeposition from aqueous solution on various substrates (carbon-based, F-doped SnO2) is presented. CuSCN is a promising solid p-type inorganic semiconductor used in perovskite solar cells as a hole-transporting material. SEM characterization reveals that the CuSCN layers are homogenous with a thickness of ca. 550 nm. Raman spectra of dry CuSCN layers show that the SCN ion is predominantly bonded in the thiocyanate resonant form to copper through its S−end (Cu−S−C≡N). The double-layer capacitance of the CuSCN layers ranges from 0.3 mF/cm2 on the boron-doped diamond to 0.8 mF/cm2 on a glass-like carbon. In situ Raman-μSEC shows that, independently of the substrate type, all Raman vibrations from CuSCN and the substrate completely vanish in the potential range from 0 to −0.3 V vs. Ag/AgCl, caused by the formation of a passivation layer. At positive potentials (+0.5 V vs. Ag/AgCl), the bands corresponding to the CuSCN vibrations change their intensities compared to those in the as-prepared, dry layers. The changes concern mainly the Cu−SCN form, showing the dependence of the related vibrations on the substrate type and thus on the local environment modifying the delocalization on the Cu−S bond. Full article
(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)
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Article
Enhanced Light Absorption by Facile Patterning of Nano-Grating on Mesoporous TiO2 Photoelectrode for Cesium Lead Halide Perovskite Solar Cells
Nanomaterials 2021, 11(5), 1233; https://doi.org/10.3390/nano11051233 - 07 May 2021
Cited by 1 | Viewed by 596
Abstract
CsPbIBr2, a cesium-based all-inorganic halide perovskite (CsPe), is a very promising alternative material to mainstream organic–inorganic hybrid halide perovskite (HPe) materials owing to its exceptional moisture stability, thermal stability, and light stability. However, because of the wide band gap (2.05 eV) [...] Read more.
CsPbIBr2, a cesium-based all-inorganic halide perovskite (CsPe), is a very promising alternative material to mainstream organic–inorganic hybrid halide perovskite (HPe) materials owing to its exceptional moisture stability, thermal stability, and light stability. However, because of the wide band gap (2.05 eV) of CsPbIBr2, it has a low power conversion efficiency (PCE), which hinders its application in highly efficient solar cells. In this study, a facile nanoimprinted one-dimensional grating nanopattern (1D GNP) formation on mesoporous TiO2 (mp-TiO2) photoelectrodes was introduced to improve the effective light utilization and enhance the performance of CsPbIBr2 perovskite solar cells (PSCs). The 1D GNP structure on the mp-TiO2 layer increases the light absorption efficiency by diffracting the unabsorbed light into the active mp-TiO2 and CsPbIBr2 layers as well as increasing the charge separation and collection due to the extended interfacial contact area between the mp-TiO2 and CsPbIBr2 layers. Consequently, both the current density (JSC) and the fill factor (FF) of the fabricated cells improved, leading to over a 20% enhancement in the solar cell’s PCE. Thus, this periodic grating structure, fabricated by simple nanoimprinting, could play an important role in the large-scale production of highly efficient and cost-effective Cs-based PSCs. Full article
(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)
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Article
Low-Temperature Processed TiOx Electron Transport Layer for Efficient Planar Perovskite Solar Cells
Nanomaterials 2020, 10(9), 1676; https://doi.org/10.3390/nano10091676 - 26 Aug 2020
Cited by 2 | Viewed by 1233
Abstract
The most frequently used n-type electron transport layer (ETL) in high-efficiency perovskite solar cells (PSCs) is based on titanium oxide (TiO2) films, involving a high-temperature sintering (>450 °C) process. In this work, a dense, uniform, and pinhole-free compact titanium dioxide (TiO [...] Read more.
The most frequently used n-type electron transport layer (ETL) in high-efficiency perovskite solar cells (PSCs) is based on titanium oxide (TiO2) films, involving a high-temperature sintering (>450 °C) process. In this work, a dense, uniform, and pinhole-free compact titanium dioxide (TiOx) film was prepared via a facile chemical bath deposition process at a low temperature (80 °C), and was applied as a high-quality ETL for efficient planar PSCs. We tested and compared as-deposited substrates sintered at low temperatures (< 150 °C) and high temperatures (> 450 °C), as well as their corresponding photovoltaic properties. PSCs with a high-temperature treated TiO2 compact layer (CL) exhibited power conversion efficiencies (PCEs) as high as 15.50%, which was close to those of PSCs with low-temperature treated TiOx (14.51%). This indicates that low-temperature treated TiOx can be a potential ETL candidate for planar PSCs. In summary, this work reports on the fabrication of low-temperature processed PSCs, and can be of interest for the design and fabrication of future low-cost and flexible solar modules. Full article
(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)
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Article
Hydrogel Electrolytes Based on Xanthan Gum: Green Route towards Stable Dye-Sensitized Solar Cells
Nanomaterials 2020, 10(8), 1585; https://doi.org/10.3390/nano10081585 - 12 Aug 2020
Cited by 73 | Viewed by 2046
Abstract
The investigation of innovative electrolytes based on nontoxic and nonflammable solvents is an up-to-date, intriguing challenge to push forward the environmental sustainability of dye-sensitized solar cells (DSSCs). Water is one of the best choices, thus 100% aqueous electrolytes are proposed in this work, [...] Read more.
The investigation of innovative electrolytes based on nontoxic and nonflammable solvents is an up-to-date, intriguing challenge to push forward the environmental sustainability of dye-sensitized solar cells (DSSCs). Water is one of the best choices, thus 100% aqueous electrolytes are proposed in this work, which are gelled with xanthan gum. This well-known biosourced polymer matrix is able to form stable and easily processable hydrogel electrolytes based on the iodide/triiodide redox couple. An experimental strategy, also supported by the multivariate chemometric approach, is used here to study the main factors influencing DSSCs efficiency and stability, leading to an optimized system able to improve its efficiency by 20% even after a 1200 h aging test, and reaching an overall performance superior to 2.7%. In-depth photoelectrochemical investigation demonstrates that DSSCs performance based on hydrogel electrolytes depends on many factors (e.g., dipping conditions, redox mediator concentrations, etc.), that must be carefully quantified and correlated in order to optimize these hydrogels. Photovoltaic performances are also extremely reproducible and stable in an open cell filled in air atmosphere, noticeably without any vacuum treatments. Full article
(This article belongs to the Special Issue Mesoporous Materials and Nanoscale Phenomena in Hybrid Photovoltaics)
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