Materials

Research

18 pages, 5030 KiB

Open AccessArticle

Impact of the RF Power on the Copper Nitride Films Deposited in a Pure Nitrogen Environment for Applications as Eco-Friendly Solar Absorber

by M. I. Rodríguez-Tapiador, J. Merino, T. Jawhari, A. L. Muñoz-Rosas, J. Bertomeu and S. Fernández

Materials 2023, 16(4), 1508; https://doi.org/10.3390/ma16041508 - 10 Feb 2023

Cited by 5 | Viewed by 1395

Abstract

This material can be considered to be an interesting eco-friendly choice to be used in the photovoltaic field. In this work, we present the fabrication of Cu₃N thin films by reactive radio-frequency (RF) magnetron sputtering at room temperature, using nitrogen as [...] Read more.

This material can be considered to be an interesting eco-friendly choice to be used in the photovoltaic field. In this work, we present the fabrication of Cu₃N thin films by reactive radio-frequency (RF) magnetron sputtering at room temperature, using nitrogen as the process gas. Different RF power values ranged from 25 to 200 W and gas pressures of 3.5 and 5 Pa were tested to determine their impact on the film properties. The morphology and structure were exhaustively examined by Atomic Force Microscopy (AFM), Fourier Transform Infrared (FTIR) and Raman Spectroscopies and X-ray Diffraction (XRD), respectively. The AFM micrographs revealed different morphologies depending on the total pressure used, and rougher surfaces when the films were deposited at the lowest pressure; whereas FTIR and Raman spectra exhibited the characteristics bands related to the Cu-N bonds of Cu₃N. Such bands became narrower as the RF power increased. XRD patterns showed the (100) plane as the preferred orientation, that changed to (111) with the RF power, revealing a worsening in structural quality. Finally, the band gap energy was estimated from transmission spectra carried out with a Perkin Elmer 1050 spectrophotometer to evaluate the suitability of Cu₃N as a light absorber. The values obtained demonstrated the capability of Cu₃N for solar energy conversion applications, indicating a better film performance under the sputtering conditions 5.0 Pa and RF power values ranged from 50 to 100 W. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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13 pages, 2781 KiB

Open AccessArticle

Plasmon-Induced Enhanced Light Emission and Ultrafast Carrier Dynamics in a Tunable Molybdenum Disulfide-Gallium Nitride Heterostructure

by Yuba Poudel, Sairaman Seetharaman, Swastik Kar, Francis D’Souza and Arup Neogi

Materials 2022, 15(21), 7422; https://doi.org/10.3390/ma15217422 - 22 Oct 2022

Viewed by 1500

Abstract

The effect of localized plasmon on the photoemission and absorption in hybrid molybdenum disulfide-Gallium nitride (MoS₂-GaN) heterostructure has been studied. Localized plasmon induced by platinum nanoparticles was resonantly coupled to the bandedge states of GaN to enhance the UV emission from [...] Read more.

The effect of localized plasmon on the photoemission and absorption in hybrid molybdenum disulfide-Gallium nitride (MoS₂-GaN) heterostructure has been studied. Localized plasmon induced by platinum nanoparticles was resonantly coupled to the bandedge states of GaN to enhance the UV emission from the hybrid semiconductor system. The presence of the platinum nanoparticles also increases the effective absorption and the transient gain of the excitonic absorption in MoS₂. Localized plasmons were also resonantly coupled to the defect states of GaN and the exciton states using gold nanoparticles. The transfer of hot carriers from Au plasmons to the conduction band of MoS₂ and the trapping of excited carriers in MoS₂ within GaN defects results in transient plasmon-induced transparency at ~1.28 ps. Selective optical excitation of the specific resonances in the presence of the localized plasmons can be used to tune the absorption or emission properties of this layered 2D-3D semiconductor material system. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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16 pages, 6598 KiB

Open AccessArticle

Morphology and Optical Properties of Gas-Phase-Synthesized Plasmonic Nanoparticles: Cu and Cu/MgO

by Sergio D’Addato, Matteo Lanza, Anthea Boiani, Eleonora Spurio, Samuele Pelatti, Guido Paolicelli and Paola Luches

Materials 2022, 15(13), 4429; https://doi.org/10.3390/ma15134429 - 23 Jun 2022

Viewed by 1331

Abstract

In this paper, an investigation of the properties of Cu and Cu/MgO nanoparticles (NPs) is presented. The NPs were obtained with gas-phase synthesis, and the MgO shells or matrices were formed via the co-deposition method on inert substrates. SEM and AFM were used [...] Read more.

In this paper, an investigation of the properties of Cu and Cu/MgO nanoparticles (NPs) is presented. The NPs were obtained with gas-phase synthesis, and the MgO shells or matrices were formed via the co-deposition method on inert substrates. SEM and AFM were used to investigate the NP morphology on Si/SiO_x, quartz, and HOPG. The Cu NPs revealed flattening of their shape, and when they were deposited on HOPG, diffusion and formation of small chains were observed. The embedding of Cu NPs in MgO was confirmed by TEM and EDX maps. XPS showed that Cu was in its metallic state, regardless of the presence of the surrounding MgO. UV–Vis revealed the presence of an intense localized surface plasmon resonance (LSPR) for Cu/MgO and for “bare” NPs. These results confirmed the role of MgO as a protective transparent medium for Cu, and the wavelength position of the LSPR in the Cu/MgO system was consistent with calculations. The wavelength position of the LSPR observed for “bare” and post-oxidized Cu NPs was probably affected by the formation of copper oxide shells after exposure to air. This study paves the way for the use of Cu/MgO NPs as plasmonic nanomaterials in applications such as photovoltaics and sensor technology. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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17 pages, 2527 KiB

Open AccessArticle

Roles of Low Temperature Sputtered Indium Tin Oxide for Solar Photovoltaic Technology

by Susana Fernández, José Pablo González, Javier Grandal, Alejandro F. Braña, María Belén Gómez-Mancebo and José Javier Gandía

Materials 2021, 14(24), 7758; https://doi.org/10.3390/ma14247758 - 15 Dec 2021

Cited by 4 | Viewed by 1883

Abstract

Different functionalities of materials based on indium tin oxide and fabricated at soft conditions were investigated with the goal of being used in a next generation of solar photovoltaic devices. These thin films were fabricated in a commercial UNIVEX 450B magnetron sputtering. The [...] Read more.

Different functionalities of materials based on indium tin oxide and fabricated at soft conditions were investigated with the goal of being used in a next generation of solar photovoltaic devices. These thin films were fabricated in a commercial UNIVEX 450B magnetron sputtering. The first studied functionality consisted of an effective n-type doped layer in an n-p heterojunction based on p-type crystalline silicon. At this point, the impact of the ITO film thickness (varied from 45 to 140 nm) and the substrate temperature (varied from room temperature to 250 °C) on the heterojunction parameters was evaluated separately. To avoid possible damages in the heterojunction interface, the applied ITO power was purposely set as low as 25 W; and to minimize the energy consumption, no heat treatment process was used. The second functionality consisted of indium-saving transparent conductive multicomponent materials for full spectrum applications. This was carried out by the doping of the ITO matrix with transition metals, as titanium and zinc. This action can reduce the production cost without sacrificing the optoelectronic film properties. The morphology, chemical, structural nature and optoelectronic properties were evaluated as function of the doping concentrations. The results revealed low manufactured and suitable films used successfully as conventional emitter, and near-infrared extended transparent conductive materials with superior performance that conventional ones, useful for full spectrum applications. Both can open interesting choices for cost-effective photovoltaic technologies. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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12 pages, 1607 KiB

Open AccessArticle

III-Nitrides Resonant Cavity Photodetector Devices

by Susana Fernández, Fernando B. Naranjo, Miguel Ángel Sánchez-García and Enrique Calleja

Materials 2020, 13(19), 4428; https://doi.org/10.3390/ma13194428 - 05 Oct 2020

Cited by 7 | Viewed by 1840

Abstract

III-nitride resonant cavity-enhanced Schottky barrier photodetectors were fabricated on 2 µm thick GaN templates by radio frequency plasma-assisted molecular beam epitaxy. The optical cavity was formed by a bottom distributed Bragg reflector based on 10 periods of Al_0.3Ga_0.7N/GaN, an [...] Read more.

III-nitride resonant cavity-enhanced Schottky barrier photodetectors were fabricated on 2 µm thick GaN templates by radio frequency plasma-assisted molecular beam epitaxy. The optical cavity was formed by a bottom distributed Bragg reflector based on 10 periods of Al_0.3Ga_0.7N/GaN, an Au-based Schottky contact as top mirror, and an active zone of 40 nm-thick GaN layer. The devices were fabricated with planar geometry. To evaluate the main benefits allowed by the optical cavity, conventional Schottky photodetectors were also processed. The results revealed a planar spectral response for the conventional photodetector, unlike the resonant devices that showed two raised peaks at 330 and 358 nm with responsivities of 0.34 and 0.39 mA/W, respectively. Both values were 80 times higher than the planar response of the conventional device. These results demonstrate the strong effect of the optical cavity to achieve the desired wavelength selectivity and to enhance the optical field thanks to the light resonance into the optical cavity. The research of such a combination of nitride-based Bragg mirror and thin active layer is the kernel of the present paper. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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11 pages, 3748 KiB

Open AccessArticle

Al_xIn_1−xN on Si (100) Solar Cells (x = 0–0.56) Deposited by RF Sputtering

by Sirona Valdueza-Felip, Rodrigo Blasco, Javier Olea, Alba Díaz-Lobo, Alejandro F. Braña and Fernando B. Naranjo

Materials 2020, 13(10), 2336; https://doi.org/10.3390/ma13102336 - 19 May 2020

Cited by 4 | Viewed by 2051

Abstract

We investigate the photovoltaic performance of solar cells based on n-Al_xIn_1−xN (x = 0–0.56) on p-Si (100) hetero-junctions deposited by radio frequency sputtering. The Al_xIn_1−xN layers own an optical bandgap absorption edge tuneable from 1.73 [...] Read more.

We investigate the photovoltaic performance of solar cells based on n-Al_xIn_1−xN (x = 0–0.56) on p-Si (100) hetero-junctions deposited by radio frequency sputtering. The Al_xIn_1−xN layers own an optical bandgap absorption edge tuneable from 1.73 eV to 2.56 eV within the Al content range. This increase of Al content results in more resistive layers (≈10⁻⁴–1 Ω·cm) while the residual carrier concentration drops from ~10²¹ to ~10¹⁹ cm⁻³. As a result, the top n-contact resistance varies from ≈10⁻¹ to 1 MΩ for InN to Al_0.56In_0.44N-based devices, respectively. Best results are obtained for devices with 28% Al that exhibit a broad external quantum efficiency covering the full solar spectrum with a maximum of 80% at 750 nm, an open-circuit voltage of 0.39 V, a short-circuit current density of 17.1 mA/cm² and a conversion efficiency of 2.12% under air mass 1.5 global (AM1.5G) illumination (1 sun), rendering them promising for novel low-cost III-nitride on Si photovoltaic devices. For Al contents above 28%, the electrical performance of the structures lessens due to the high top-contact resistivity. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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12 pages, 3648 KiB

Open AccessArticle

Processing and Study of Optical and Electrical Properties of (Mg, Al) Co-Doped ZnO Thin Films Prepared by RF Magnetron Sputtering for Photovoltaic Application

by Chayma Abed, Susana Fernández, Selma Aouida, Habib Elhouichet, Fernando Priego, Yolanda Castro, M. B. Gómez-Mancebo and Carmen Munuera

Materials 2020, 13(9), 2146; https://doi.org/10.3390/ma13092146 - 06 May 2020

Cited by 15 | Viewed by 2284

Abstract

In this study, high transparent thin films were prepared by radio frequency (RF) magnetron sputtering from a conventional solid state target based on ZnO:MgO:Al₂O₃ (10:2 wt %) material. The films were deposited on glass and silicon substrates at the different [...] Read more.

In this study, high transparent thin films were prepared by radio frequency (RF) magnetron sputtering from a conventional solid state target based on ZnO:MgO:Al₂O₃ (10:2 wt %) material. The films were deposited on glass and silicon substrates at the different working pressures of 0.21, 0.61, 0.83 and 1 Pa, 300 °C and 250 W of power. X-ray diffraction patterns (XRD), atomic force microscopy (AFM), UV-vis absorption and Hall effect measurements were used to evaluate the structural, optical, morphological and electrical properties of thin films as a function of the working pressure. The optical properties of the films, such as the refractive index, the extinction coefficient and the band gap energy were systematically studied. The optical band gap of thin films was estimated from the calculated absorption coefficient. That parameter, ranged from 3.921 to 3.655 eV, was hardly influenced by the working pressure. On the other hand, the lowest resistivity of 8.8 × 10⁻² Ω cm⁻¹ was achieved by the sample deposited at the lowest working pressure of 0.21 Pa. This film exhibited the best optoelectronic properties. All these data revealed that the prepared thin layers would offer a good capability to be used in photovoltaic applications. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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7 pages, 6298 KiB

Open AccessArticle

Vanadium-Oxide-Based Thin Films with Ultra-High Thermo-Optic Coefficients at 1550 nm and 2000 nm Wavelengths

by Mohamed Abdel-Rahman, Esam Bahidra and Ahmed Fauzi Abas

Materials 2020, 13(8), 2002; https://doi.org/10.3390/ma13082002 - 24 Apr 2020

Cited by 2 | Viewed by 2260

Abstract

In this paper, the temperature-dependent dielectric properties of vanadium-sesquioxide-based thin films are studied to assess their suitability for thermally tunable filters at optical communication wavelengths. Spectroscopic ellipsometry is utilized to measure the optical constants of vanadium oxide thin films at temperatures ranging from [...] Read more.

In this paper, the temperature-dependent dielectric properties of vanadium-sesquioxide-based thin films are studied to assess their suitability for thermally tunable filters at optical communication wavelengths. Spectroscopic ellipsometry is utilized to measure the optical constants of vanadium oxide thin films at temperatures ranging from 25 °C to 65 °C. High thermo-optic coefficients (dn/dTs) were observed. The highest dn/dTs, measured at approximately 40 °C, were −8.4 × 10⁻³/°C and −1.05 × 10⁻²/°C at 1550 nm and 2000 nm, respectively. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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11 pages, 2379 KiB

Open AccessArticle

How Reproducible are Electrochemical Impedance Spectroscopic Data for Dye-Sensitized Solar Cells?

by Mariia Becker, Maria-Sophie Bertrams, Edwin C. Constable and Catherine E. Housecroft

Materials 2020, 13(7), 1547; https://doi.org/10.3390/ma13071547 - 27 Mar 2020

Cited by 6 | Viewed by 2344

Abstract

Dye-sensitized solar cell (DSC) technology has been broadly investigated over the past few decades. The sandwich-type structure of the DSC makes the manufacturing undemanding under laboratory conditions but results in the need for reproducible measurements for acceptable DSC characterization. Electrochemical impedance spectroscopy (EIS) [...] Read more.

Dye-sensitized solar cell (DSC) technology has been broadly investigated over the past few decades. The sandwich-type structure of the DSC makes the manufacturing undemanding under laboratory conditions but results in the need for reproducible measurements for acceptable DSC characterization. Electrochemical impedance spectroscopy (EIS) offers the possibility to study complex electronic systems and is commonly used for solar cells. There is a tendency in the literature to present impedance data only for one representative device. At the same time, as current density–voltage plots illustrate, measurements can vary within one set of DSCs with identical components. We present multiple DSC impedance measurements on “identical” devices prepared using two different dyes and present a statistical analysis regarding the reproducibility. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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17 pages, 4619 KiB

Open AccessArticle

There Is a Future for N-Heterocyclic Carbene Iron(II) Dyes in Dye-Sensitized Solar Cells: Improving Performance through Changes in the Electrolyte

by Mariia Karpacheva, Vanessa Wyss, Catherine E. Housecroft and Edwin C. Constable

Materials 2019, 12(24), 4181; https://doi.org/10.3390/ma12244181 - 12 Dec 2019

Cited by 9 | Viewed by 2511

Abstract

By systematic tuning of the components of the electrolyte, the performances of dye-sensitized solar cells (DSCs) with an N-heterocyclic carbene iron(II) dye have been significantly improved. The beneficial effects of an increased Li⁺ ion concentration in the electrolyte lead to photoconversion [...] Read more.

By systematic tuning of the components of the electrolyte, the performances of dye-sensitized solar cells (DSCs) with an N-heterocyclic carbene iron(II) dye have been significantly improved. The beneficial effects of an increased Li⁺ ion concentration in the electrolyte lead to photoconversion efficiencies (PCEs) up to 0.66% for fully masked cells (representing 11.8% relative to 100% set for N719) and an external quantum efficiency maximum (EQE_max) up to approximately 25% due to an increased short-circuit current density (J_SC). A study of the effects of varying the length of the alkyl chain in 1-alkyl-3-methylimidazolium iodide ionic liquids (ILs) shows that a longer chain results in an increase in J_SC with an overall efficiency up to 0.61% (10.9% relative to N719 set at 100%) on going from n-methyl to n-butyl chain, although an n-hexyl chain leads to no further gain in PCE. The results of electrochemical impedance spectroscopy (EIS) support the trends in J_SC and open-circuit voltage (V_OC) parameters. A change in the counterion from I⁻ to [BF₄]⁻ for 1-propyl-3-methylimidazolium iodide ionic liquid leads to DSCs with a remarkably high J_SC value for an N-heterocyclic carbene iron(II) dye of 4.90 mA cm⁻², but a low V_OC of 244 mV. Our investigations have shown that an increased concentration of Li⁺ in combination with an optimized alkyl chain length in the 1-alkyl-3-methylimidazolium iodide IL in the electrolyte leads to iron(II)-sensitized DSC performances comparable with those of containing some copper(I)-based dyes. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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12 pages, 3818 KiB

Open AccessArticle

The Size Effect of TiO₂ Hollow Microspheres on Photovoltaic Performance of ZnS/CdS Quantum Dots Sensitized Solar Cell

by Zhen Li and Libo Yu

Materials 2019, 12(10), 1583; https://doi.org/10.3390/ma12101583 - 15 May 2019

Cited by 13 | Viewed by 3425

Abstract

Size controllable TiO₂ hollow microspheres (HMS) were synthesized by a carbonaceous spheres (CS) template method. Based on TiO₂ HMS, the ZnS/CdS quantum dots (QDs) were loaded to form a ZnS/CdS@TiO₂ HMS photoanode for quantum dots sensitized solar cell (QDSSC). The [...] Read more.

Size controllable TiO₂ hollow microspheres (HMS) were synthesized by a carbonaceous spheres (CS) template method. Based on TiO₂ HMS, the ZnS/CdS quantum dots (QDs) were loaded to form a ZnS/CdS@TiO₂ HMS photoanode for quantum dots sensitized solar cell (QDSSC). The size effects of TiO₂ HMS on photovoltaic performance were investigated, and showed that TiO₂ HMS with sizes ~560 nm produced the best short-circuit current density (J_sc) of 8.02 mA cm⁻² and highest power conversion efficiency (PCE) of 1.83%, showing a better photovoltaic performance than any other QDSSCs based on TiO₂ HMS with size ~330 nm, ~400 nm, and ~700 nm. The improvement of photovoltaic performance based on ~560 nm TiO₂ HMS which can be ascribed to the enhanced light harvesting efficiency caused by multiple light reflection and strong light scattering of TiO₂ HMS. The ultraviolet-visible (UV-vis) spectra and incident photo to the current conversion efficiency (IPCE) test results confirmed that the size of TiO₂ HMS has an obvious effect on light harvesting efficiency. A further application of ~560 nm TiO₂ HMS in ZnS/PbS/CdS QDSSC can improve the PCE to 2.73%, showing that TiO₂ HMS has wide applicability in the design of QDSSCs. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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9 pages, 3461 KiB

Open AccessArticle

High-Quality Perovskite CH₃NH₃PbI₃ Thin Films for Solar Cells Prepared by Single-Source Thermal Evaporation Combined with Solvent Treatment

by Huanxin Peng, Zhenghua Su, Zhuanghao Zheng, Huabin Lan, Jingting Luo, Ping Fan and Guangxing Liang

Materials 2019, 12(8), 1237; https://doi.org/10.3390/ma12081237 - 15 Apr 2019

Cited by 25 | Viewed by 4241

Abstract

In this work, solvent annealing process for CH₃NH₃PbI₃ thin film prepared by single source evaporation was reported. Characterized by the scanning electron microscope (SEM), X-ray diffractometer (XRD), energy dispersive spectroscope (EDS), ultraviolet-visible (UV) spectrophotometer, and the photoluminescence (PL) [...] Read more.

In this work, solvent annealing process for CH₃NH₃PbI₃ thin film prepared by single source evaporation was reported. Characterized by the scanning electron microscope (SEM), X-ray diffractometer (XRD), energy dispersive spectroscope (EDS), ultraviolet-visible (UV) spectrophotometer, and the photoluminescence (PL) spectrometer, our method ensured higher quality film with crystallinity, composition, well-defined grain structure, and reproducibility. The optimized solar cell device based on the structure of ITO/PEDOT:PSS/CH₃NH₃PbI₃/PCBM/Ag achieved better performance in power conversion efficiency from 2.64% to 9.92%, providing an effective method to optimize the quality of perovskite film for solar cell application. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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Review

Jump to: Research, Other

33 pages, 7644 KiB

Open AccessEditor’s ChoiceReview

Application of Graphene-Related Materials in Organic Solar Cells

by Lara Velasco Davoise, Ana M. Díez-Pascual and Rafael Peña Capilla

Materials 2022, 15(3), 1171; https://doi.org/10.3390/ma15031171 - 03 Feb 2022

Cited by 18 | Viewed by 3707

Abstract

Graphene-related materials (GRMs) such as graphene quantum dots (GQDs), graphene oxide (GO), reduced graphene oxide (rGO), graphene nanoribbons (GNRs), and so forth have recently emerged as photovoltaic (PV) materials due to their nanodimensional structure and outstanding properties such as high electrical and thermal [...] Read more.

Graphene-related materials (GRMs) such as graphene quantum dots (GQDs), graphene oxide (GO), reduced graphene oxide (rGO), graphene nanoribbons (GNRs), and so forth have recently emerged as photovoltaic (PV) materials due to their nanodimensional structure and outstanding properties such as high electrical and thermal conductivity, large specific surface, and unique combination of mechanical strength and flexibility. They can be a crucial part of transparent electrodes, hole/electron transport materials, and active layers in organic solar cells (OSCs). Besides their role in charge extraction and transport, GRMs act as device protectors against environmental degradation through their compact bidimensional structure and offer good durability. This review briefly presents the synthesis methods of GRMs and describes the current progress in GRM-based OSCs. PV parameters (short circuit current, open circuit voltage, power conversion efficiency, and fill factor) are summarized and comparatively discussed for the different structures. The efficiency recently surpassed 15% for an OSC incorporating polymer-modified graphene as a transparent electrode. The long-term stability of OSCs incorporating GRMs is also discussed. Finally, conclusions and the outlook for future investigation into GRM-based devices for PVs are presented. Full article

(This article belongs to the Special Issue Advanced Materials for Photonics and Photovoltaics Applications)

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