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Improved performance with molecular design of Ruthenium(II) complexes bearing diamine-based bidentate ligands as sensitizer for dye-sensitized solar cells (DSSC)
摘要： Herein, the derivatives of ruthenium(II) complexes bearing different diaminobenzene backbones were produced with the idea of molecular design and characterized. These complexes which are intended to be used as photoactive dyes in a DSSC device also contain suitable optoelectronic properties and the ligands capable of acting in accordance with the DSSC mechanism. The power conversion efficiencies (PCEs) of the first series synthesized ruthenium(II) complexes (5-8A) in DSSC tests were obtained in the range of 0.64 – 2.25%. Among these backbone structures, the superiority of the benzophenone structure, namely 8A, has been observed and its derivatives have been produced as a second series. The ruthenium(II) complexes produced as 8B and 8C were tested to see the effect of different functional groups on solar cell performances and although the power conversion efficiencies of these complexes were lower than the performance of 8A, they approached with 1.63% and 2.05% values. Thus, the effect of different functional and backbone group structures in the molecular structure on DSSC efficiencies was determined directly and it was emphasized that there could be significant increases in cell performances with the change of simple functional groups.
关键词： Bidentate,Solar Cell,DSSC,Ruthenium dye,Sulfonamide,Diaminobenzene
更新于2025-09-23 15:19:57
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Investigation of interface characteristics of Al2O3/Si under various O2 plasma exposure times during the deposition of Al2O3 by PA-ALD
摘要： Plasma-assisted atomic layer deposition (PA-ALD) is more suitable than thermal atomic layer deposition (ALD) for mass production because of its faster growth rate. However, controlling surface damage caused by plasma during the PA-ALD process is a key issue. In this study, the passivation characteristics of Al2O3 layers deposited by PA-ALD were investigated with various O2 plasma exposure times. The growth per cycle (GPC) during Al2O3 deposition was saturated at approximately 1.4 ?/cycle after an O2 plasma exposure time of 1.5 s, and a refractive index of Al2O3 in the range of 1.65–1.67 was obtained. As the O2 plasma exposure time increased in the Al2O3 deposition process, the passivation properties tended to deteriorate, and as the radio frequency (RF) power increased, the passivation uniformity and the thermal stability of the Al2O3 layer deteriorated. To study the Al2O3/Si interface characteristics, the capacitance-voltage (C-V) and the conductance-voltage (G-V) were measured using a mercury probe, and the ?xed charge density (Qf) and the interface trap density (Dit) were then extracted. The Qf of the Al2O3 layer deposited on a Si wafer by PA-ALD was almost una?ected, but the Dit increased with O2 plasma exposure time. In conclusion, as the O2 plasma exposure time increased during Al2O3 layer deposition by PA-ALD, the Al2O3/Si interface characteristics deteriorated because of plasma surface damage.
关键词： Plasma-assisted atomic layer deposition,Plasma damage,Silicon solar cell,Passivation,Al2O3
更新于2025-09-23 15:19:57
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Optical properties of the perovskite films deposited on meso-porous TiO2 by one step and hot casting techniques
摘要： In this work, CH3NH3PbI3 is coated on meso-porous TiO2 films via one step method (OSM) and hot casting technique (HCT). The optical properties of the solution-processed organic inorganic halide perovskite layers deposited on meso-structured TiO2 scaffolds are investigated using UV–Vis reflectance and transmittance spectroscopies at the wavelength range of 400–900 nm. Optical parameters including refractive index, extinction coefficient, real and imaginary parts of the dielectric constants, optical conductivity and direct and indirect optical band gaps are calculated and compared for the perovskite films created by above mentioned methods. Optical band gaps are determined from the absorption coefficient values using Tauc's power law. The obtained values of direct band gap for two perovskite films are close to each other (1.56 and 1.58 eV for perovskite layer deposited by OSM and HCT respectively). For both prepared films, the difference between direct and indirect band gaps is 60 meV which is in very good agreement with that reported in literature. In addition to the difference between the perovskite morphology, the optical absorption of perovskite layers created by the HCT is less than that of layers prepared by OSM and therefore the amount of generated photo current is less. This is the main reason that causes the efficiency of perovskite solar cells prepared by HCT (3.0 %) is ~38% less than that of cells created by OSM (4.15 %).
关键词： Spin Coating,one step,Hot casting,Optical properties,Perovskite solar cell
更新于2025-09-23 15:19:57
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Effect of seed layer on growth of rutile TiO <sub/>2</sub> nanorods
摘要： For achieving the high quality of titanium dioxide (TiO2) nanorods, herein, we present a synthesis of rutile TiO2 nanorods on a transparent conductive fluorine-doped tin oxide (FTO) glass substratewith seed layer by a two-step method. TiO2 thin films were first precoated by spin coating and annealing, followed by the growth of TiO2 nanorods with a hydrothermal method. The crystallographic nanostructures and properties of the nanorods were investigated. XRD results demonstrate that seed layer was tetragonal anatase TiO2 structure while nanorods had tetragonal rutile TiO2 structure. Since the hydrothermal technique was conducted in medium acid, structure of nanorods was induced to form in rutile phase. The major characteristic orientation of nanorods on the seed layers was (002) and minor in (101) planes. FE-SEM results show that seed layer enhances the process to achieve vertical-aligned orientation of the TiO2 nanorods, which contribute to develop electron transport rate and could pay an important role inelectron transport layer in high-performance Perovskite solar cell.
关键词： seed layer,hydrothermal method,rutile TiO2 nanorods,Perovskite solar cell,electron transport layer
更新于2025-09-23 15:19:57
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DFT study of electronic structure and optical properties of layered two-dimensional CH <sub/>3</sub> NH <sub/>3</sub> PbX <sub/>3</sub> (X=Cl, Br, I)
摘要： Two-dimensional (2D) organic–inorganic hybrid halide perovskites (OIHPs) have been considered by researchers in the field of solar cells due to their high-temperature stability. In this paper, the electronic and optical properties of single-layer (SL) and multilayer (ML) structures of MAPbX3 (X = Cl, Br, I and MA = CH3NH3) have been studied by density functional theory (DFT) in order to predict its photovoltaic capabilities. The results have shown that SL- and ML-MAPbX3 have a direct band gap in the range of 1.76–2.70 eV. The calculation of dielectric constants has depicted that the static dielectric constants (SDCs) of SL-MAPbX3 are smaller than SDCs of ML-MAPbX3. However, as we expected, the reaction of the structures to in-plane (║) and out-of-plane (┴) polarizations was different; therefore, the SL- and ML-MAPbX3 (X = Cl, Br, I) were optically anisotropic. In addition, the intensity of the optical absorption spectrum for ML-MAPbX3 structures is approximately three times higher than that of SL-MAPbX3 structures. By increasing the radius of halogens (RCl<RBr<RI), surface area under the absorption curve increases and absorbs more. Furthermore, our results have shown that the electronic and optical behavior of 2D-MAPbX3 is suitable for photovoltaic applications and makes them useful for OIHP solar cells.
关键词： optical properties,DFT,2D-MAPbX3,organic–inorganic hybrid halide perovskites,solar cell
更新于2025-09-19 17:15:36
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Absorption of light in a single vertical nanowire and a nanowire array
摘要： Both a single III–V semiconductor nanowire and an array of such nanowires have shown promise for solar cell applications. However, the correspondence between the optical properties of the single nanowire and the nanowire array has not been studied. Here, we perform electromagnetic modeling of InP nanowires to study this relationship. We find that a single nanowire can show at an absorption peak, a remarkably high absorption cross-section that is more than 50 times the geometrical cross-section. With optimization of the diameter of the single nanowire, the short-circuit current density is 30 times higher than in a bulk solar cell. With such a strong absorption, we predict an apparent efficiency >500% for the single nanowire solar cell. In contrast, we show that an efficient nanowire array solar cell cannot rely on strong absorption just through the absorption peak. Instead, the nanowires need to be packed rather closely to enhance the absorption of the full solar spectrum. At the optimum diameter for the nanowire array, neighboring nanowires compete strongly for absorption of incident photons at the absorption peak, which limits the absorption per nanowire by a factor of 18. As a result, the single InP nanowire is optimized at a diameter of 110 nm while the nanowires in the array are optimized at a considerably larger diameter of 180 nm. Importantly, we show analytically the coupling efficiency of incident light into the fundamental HE11 guided mode and consecutive absorption of the mode in the nanowires. With that analysis, we explain that a single nanowire shows two different absorption pathways—one through coupling into the guided mode and another by coupling into the nanowire through the sidewall. This analytical analysis also shows at which period the neighboring nanowires in an array start to compete for absorption of incident photons.
关键词： III–V semiconductor nanowire,optics modeling,absorption,solar cell
更新于2025-09-19 17:15:36
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Electronic Traps and its Correlations to Perovskite Solar-Cell Performance via Compositional and Thermal-Annealing Controls
摘要： Herein, underlying factors for enabling efficient and stable performance of perovskite solar cells are studied through nanostructural controls of organic-inorganic halide perovskites. Namely, MAPbI3, (FA0.83MA0.17)Pb(I0.83Br0.17)3, and (Cs0.10FA0.75MA0.15)Pb(I0.85Br0.15)3 perovskites (abbreviated as MA, FAMA, and CsFAMA, respectively) are examined with a grain growth control through thermal annealing. FAMA- and CsFAMA- based cells result in stable photovoltaic performance while MA cells are sensitively dependent on the perovskite grain size dominated by annealing time. Micro-/nanoscopic features are comprehensively analysed to unravel the origin that is directly correlated to the cell performance with the applications of electronic-trap characterizations such as photoconductive noise microscopy and capacitance analyses. It is revealed that CsFAMA has a lower trap density compared to MA and FAMA through the analyses of 1/f noises and trapping/detrapping capacitances. Also, an open-circuit voltage (Voc) change is correlated to the variation of trap states during the shelf-life test: FAMA and CsFAMA cells with the negligible change of Voc over weeks exhibit trap states shifting toward the bandedge, although the power-conversion efficiencies are clearly reduced. It is discussed about the origins that critically affect the solar cell performance through the characterizations of shallow/deep traps with additional mobile defects in the perovskite and interfaces.
关键词： 1/f noise,Organic-inorganic halide perovskite,Perovskite solar cell,Capacitance,Electronic trap
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - High-Efficiency InAs-InGaAs Quantum Dash Solar Cells Developed Through Current Constraint Engineering
摘要： In principle, quantum-dot intermediate band solar cell (QD-IBSC) operates at a higher current density than a III-V multijunction solar cell (MJSC). Due to this inherent property, heat management becomes important when it is operated under a high concentrated illumination. In this work, we propose one way to circumvent this issue, where a wide bandgap cell is placed on top of QD-IBSC, which acts as a current constraint cell, but instead leads to a higher VOC. We demonstrate a 32.1% efficiency under 225 suns with a bonded InGaP/GaAs widegap cell // InAs-InGaAs QDSC configuration.
关键词： wide bandgap cell,efficiency,VOC,III-V multijunction solar cell,concentrated illumination,quantum-dot intermediate band solar cell,MJSC,QD-IBSC,current constraint cell,heat management
更新于2025-09-19 17:13:59
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Highly transparent and conductive oxide-metal-oxide electrodes optimized at the percolation thickness of AgOx for transparent silicon thin-film solar cells
摘要： Highly transparent and conductive oxide-metal-oxide (OMO) electrodes comprising aluminum-doped zinc-oxide (AZO) and ultrathin Ag or oxygen (O2)-doped Ag (AgOx) metal layers were fabricated for use in thin-film silicon solar cells. The surface morphologies of the metal layers and the transparencies and conductivities of OMO electrodes were investigated near the percolation thickness values of the metal layers. The percolation metal thickness, which means the metal layer is morphologically continuous, could be used to optimize the transparent OMO electrode. Additionally, thin Ag-based OMO (AgOx OMO) with superior performance could be fabricated by adding O2. The optimized AgOx OMO electrodes yielded the highest average transmittance (Tavg) of 93.5% and the lowest average optical loss (OLavg) of 1.01% within 500–800 nm at the percolation thickness of ~6 nm, thus, maintaining low conductivity. These outcomes were superior to the responses of the percolated Ag OMO (Tavg = 87.2%; OLavg = 1.01%). Using the OMO structure at the rear electrode, transparent hydrogenated amorphous silicon thin-film solar was fabricated for building integrated photovoltaic windows. The best figure-of-merit (FOM; equal to the product of Tavg and efficiency η) values of the OMO-based transparent solar cells could be obtained for percolated OMO structures. The cells using AgOx OMO (AgOx cells) performed better than the Ag cells; the best FOMs of AgOx and Ag cells were 140.8 (Tavg = 27.8%; η = 5.51%) and 104.6% (Tavg = 18.9%; η = 5.54%), respectively. These results could contribute to the development of high-performance transparent solar cells or optoelectronic devices.
关键词： Oxygen-doped silver,Oxide/metal/oxide,Transparent conductive electrode,Transparent solar cell,Thin-film silicon solar cell
更新于2025-09-19 17:13:59
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Niobium doped TiO2 nanorod arrays as efficient electron transport materials in photovoltaic
摘要： One-dimensional (1-D) rutile TiO2 nanorod arrays (NRAs) synthesized by a hydrothermal method suffer from low electrical conductivity and large amounts of surface defects, hindering their further applications. Nb doping is thus introduced to modify their electronic properties. Results indicate that light Nb doping reduces rod nanosizes, increases electron concentrations, decreases surface defective oxides and lowers conduction band of the TiO2 NRAs, while heavy doping induces transformations of morphologies and crystalline orientations as well as occurrences of compositional deviations and low oxidative states of Ti3t. After 0.1 mol% and 1 mol% Nb incorporations, device efficiencies are substantially improved by ~16% and ~33% for the model perovskite and dye-sensitized solar cells, respectively, which are ascribed to reduced recombination at the perovskite/TiO2 interfaces (e.g. charge lifetime increasing from 62 μs to 107 μs) and improved electron transport through the photoanode of TiO2 NRAs (e.g. electron diffusion length increasing from ~14 μm to ~50 μm). Our study verifies that Nb doped 1-D TiO2 NRAs are versatile electron transporting materials in different kinds of emerging solar cells, and are also potential for other fields including photocatalysis, sensors and batteries etc.
关键词： TiO2 nanorod array,Dye-sensitized solar cell,Niobium doping,Charge transport,Perovskite solar cell,Recombination
更新于2025-09-19 17:13:59