Ruthenium Complexes as Sensitizers in Dye-Sensitized Solar Cells

Aghazada, Sadig; Nazeeruddin, Mohammad Khaja

doi:10.3390/inorganics6020052

Cited by 107 publications

(101 citation statements)

References 139 publications

(213 reference statements)

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“…As a result of the large energy difference between the occupied Ru d-orbitals and the unoccupied ligand orbitals, the HOMO is mainly localized at the metal and the LUMO belongs to the ligand anti-bonding orbitals. Therefore, the excitation and transition of an electron from the HOMO to the LUMO is called metal-to-ligand charge transfer (MLCT) and leads to the appearance of a photoabsorption band in the wavelength range between 380 and 520 nm [33,51]. MLCT transition corresponds to the visible spectral range; therefore, it is the most important characteristic of the complex molecule that can be used as a photosensitizer.…”

Section: Characteristics Of Ru (Ii) Heterocyclic Complexmentioning

confidence: 99%

“…In the UV range, high-energy transitions dominate in the process of intraligand π → π* charge transfer in bipyridine ligands (LC-ligand-centered) and ligand-to-metal charge transfer (LMCT) (πL → eg, Ru). The weak absorption band at 324 nm can be attributed to the transition between the metal orbitals (MC-metal-centered) (t2g, Ru → eg, Ru) [33,52,53]. The optical absorption spectrum of Ru (II) heterocyclic complex is presented in Figure 4.…”

Section: Characteristics Of Ru (Ii) Heterocyclic Complexmentioning

confidence: 99%

“…A similar effect is achieved when creating hybrid materials in which the photosensitizer is an organic dye. However, in this case, there is an additional advantage: in addition to the generation of photoexcited charge carriers and their spatial separation, the appearance of a specific activity of the organic component in reactions with gas phase molecules is possible.Ru (II) heterocyclic complexes are among the most effective photosensitizers due to its electrochemical and photophysical properties, high molar extinction coefficient in the visible range, long lifetime of the excited state, and high luminescence intensity [28][29][30][31][32][33]. Comparison of the sensor properties of nanocomposites based on nanocrystalline oxides ZnO, SnO 2 , In 2 O 3 , and CdSe quantum dots in room temperature NO 2 detection under visible light photoactivation showed that semiconductor matrices SnO 2 and In 2 O 3 provide higher sensitivity of nanocomposites toward NO 2 [25].…”

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Organic-Inorganic Hybrid Materials for Room Temperature Light-Activated Sub-ppm NO Detection

et al. 2019

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Nitric oxide (NO) is one of the main environmental pollutants and one of the biomarkers noninvasive diagnosis of respiratory diseases. Organic-inorganic hybrids based on heterocyclic Ru (II) complex and nanocrystalline semiconductor oxides SnO 2 and In 2 O 3 were studied as sensitive materials for NO detection at room temperature under periodic blue light (λ max = 470 nm) illumination. The semiconductor matrixes were obtained by chemical precipitation with subsequent thermal annealing and characterized by XRD, Raman spectroscopy, and single-point BET methods. The heterocyclic Ru (II) complex was synthesized for the first time and characterized by 1 H NMR, 13 C NMR, MALDI-TOF mass spectrometry and elemental analysis. The HOMO and LUMO energies of the Ru (II) complex are calculated from cyclic voltammetry data. The thermal stability of hybrids was investigated by thermogravimetric analysis (TGA)-MS analysis. The optical properties of Ru (II) complex, nanocrystalline oxides and hybrids were studied by UV-Vis spectroscopy in transmission and diffuse reflectance modes. DRIFT spectroscopy was performed to investigate the interaction between NO and the surface of the synthesized materials. Sensor measurements demonstrate that hybrid materials are able to detect NO at room temperature in the concentration range of 0.25-4.0 ppm with the detection limit of 69-88 ppb.Nanomaterials 2020, 10, 70 2 of 22 in noninvasive diagnosis of respiratory diseases [7][8][9]. In this case, the limitation of the quantitative determination of NO in exhaled air is due to the low level of its concentration (20-200 ppb) among a wide range of interfering gases [10].Direct determination of nitrogen monoxide in the gas phase is possible using conductometric gas sensors based on various semiconductor metal oxides [7,[10][11][12][13][14][15][16][17][18][19][20][21][22]. To increase selectivity of such analysis along with lower power consumption, complete or partial replacement of thermal heating with photoactivation is a promising approach. Activation of the sensor response under illumination occurs through various mechanisms depending on the nature of the target gas. For oxidizing gases (NO 2 , O 3 ), which compete with oxygen for the same adsorption sites, photogeneration of electron-hole pairs plays a major role in the photodesorption process. On the contrary, for the detection of reducing gases (CO, NH 3 , H 2 S), the presence of chemisorbed oxygen on the surface of the semiconductor oxide is necessary. In this case, the increase in the sensor response under illumination is due to the unpinning of Fermi level of the semiconductor. In most works NO is detected as oxidizing gas. The similar routes of NO and NO 2 sensing was recently evidenced by in situ DRIFT spectroscopy [23]. Our previous works show that highly selective NO 2 detection is possible using visible light photoactivation [24][25][26][27]. To shift the optical sensitivity of semiconductor oxides into the visible range, it is necessary to create defects in the semiconductor matrix or i...

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Section: Characteristics Of Ru (Ii) Heterocyclic Complexmentioning

confidence: 99%

Section: Characteristics Of Ru (Ii) Heterocyclic Complexmentioning

confidence: 99%

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confidence: 99%

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Organic-Inorganic Hybrid Materials for Room Temperature Light-Activated Sub-ppm NO Detection

et al. 2019

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“…The relatively high efficiencies of the ruthenium(II)‐polypyridyl DSSCs can be attributed to their wide absorption range from the visible to the near‐infrared (NIR) regime. In this regard, several attempts have been made to molecularly engineer the structure of these complexes in order to increase their molar absorption coefficient, and thus their long‐term stability . This research focuses on the synthesis and characterization of ruthenium(II) complexes modified ZnO nanoparticles to use them in the design of photoanodes for DSSCs.…”

Section: Introductionmentioning

confidence: 99%

“…In this regard, several attempts have been made to molecularly engineer the structure of these complexes in order to increase their molar absorption coefficient, and thus their long-term stability. [20][21][22][23][24] This research focuses on the synthesis and characterization of ruthenium(II) complexes modified ZnO nanoparticles to use them in the design of photoanodes for DSSCs. In a first step, 4,4'-bipyridine capped ZnO NPs were synthesized through a chemical precipitation method and further assembled with Ru (II) complexes with 2,2'-bipyridine (bpy) and 2,2'-bipyridine-4,4'dicarboxylic acid (dcbpy) as ligands.…”

Section: Introductionmentioning

confidence: 99%

ZnO Nanoparticles Photosensitization Using Ruthenium(II)‐polypyridyl Isomeric Complexes

et al. 2020

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The coordination of photosensitizing dyes to zinc oxide nanoparticles (ZnO NPs) has attracted extensive attention as promising candidates for applications in solar cells. Here, we report the synthesis of ZnO NPs functionalized with geometric isomers of ruthenium(II)‐polypyridyl complexes and a preliminary study of their photophysical properties by fluorescence spectroscopy. ZnO NPs synthesis was carried out by direct precipitation. IR, UV‐Vis spectroscopy, XRD and TG‐DTA techniques were used for ZnO NPs characterization. Trans and cis complexes of Ru(II) using 2,2′‐bipyridine and 2,2’‐bipyridine‐4,4’‐dicarboxylic acid as ligands were assembled to ZnO NPs. The presence not only of a band of around 355 nm, but also at 465 nm, in the electronic spectrum indicates the modification of the ZnO surface with the synthesized complexes. The fluorescence behaviour of Ru(II) complexes modified ZnO NPs suggested an electron transfer process through the system. Remarkably, the trans isomer modified system showed better response during the electron transfer. This information could be considered during the design of photoanodes in Dye‐Sensitized Solar Cells.

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The Role of Antireflective Coating CYTOP, Immersion Oil, and Sensitizer Selection in Fabricating a 2.3 V, 10% Power Conversion Efficiency SSM‐DSC Device

Cheema

Delcamp

2019

Advanced Energy Materials

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for maximizing power output from an illuminated area is through the use of multijunction solar cell constructs. [3] Recently, we put forward the first sequential series multijunction dye-sensitized solar cell (SSM-DSC), which could power solarto-fuel conversion directly from a single illuminated area. [4] This construct showed solar-to-fuel conversion efficiencies of up to 3% for CO 2 to CO and H 2 O to H 2 and O 2 reactions in the seminal report of a purely DSC-based technology powering these processes from a single illuminated area device without bias. [4b] The use of a DSC system to power these solar-to-fuel conversion processes is attractive due to the processability, stability, and already relatively high photovoltage outputs from DSC devices. [4a] The SSM-DSC construct capitalizes on the high photovoltages of traditional DSC devices in dividing photons according to potential energy to generate high voltage outputs through a summation of subcell photovoltages. SSM-DSC devices are simple to construct with a direct stacking of subcells sequentially wired in series. In this configuration, devices can be optimized individually in terms of TiO 2 thickness and sensitizer choice to achieve well-matched photocurrents for higher performing SSM-DSC devices since current is limited by the lowest current device in the series. However, within this design, significant light losses exist between each subcell, especially at the glass-air interface where diffraction and reflection are the highest due to significantly mismatched refractive indexes of glass (n = 1.52) and air (n = 1) (Figure 1). To minimize these losses, we put forward the use of a simple-to-apply antireflective coating in the form of CYTOP along with an immersion oil with a similar refractive index to glass between each subcell (Figure 2).CYTOP is known in the field of optoelectronics with recent uses as a gate dielectric, a support layer within devices, as a selfcleaning surface, a solution substrate patterning material, and as an insulating tunneling layer within devices. [5] No reports were apparent from our searches for the specific use of CYTOP as an antireflective coating with organic or dye-sensitized solar cells. The use of CYTOP and immersion oil as optical interfacial loss diminishing components allows for an increase of photon flux throughout the SSM-DSC system to boost photocurrent values for a more overall efficient system. Sequential series multijunction dye-sensitized solar cells (SSM-DSCs) canpower solar-to-fuel processes with a single illuminated area device. Dye selection and strategies limiting photon losses are critical in SSM-DSC devices for higher performance systems. Herein, an efficient and readily applicable spin coating protocol on glass surfaces with an antireflective fluoropolymer (CYTOP) is applied to an SSM-DSC architecture. Combining CYTOP with the use of an immersion oil between glass spacers in a three subcell SSM-DSC with judiciously selected TiO 2 photoanode sensitizers and thicknesses, an overall power conversion efficie...

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Ruthenium Complexes as Sensitizers in Dye-Sensitized Solar Cells

Cited by 107 publications

References 139 publications

Organic-Inorganic Hybrid Materials for Room Temperature Light-Activated Sub-ppm NO Detection

Organic-Inorganic Hybrid Materials for Room Temperature Light-Activated Sub-ppm NO Detection

ZnO Nanoparticles Photosensitization Using Ruthenium(II)‐polypyridyl Isomeric Complexes

The Role of Antireflective Coating CYTOP, Immersion Oil, and Sensitizer Selection in Fabricating a 2.3 V, 10% Power Conversion Efficiency SSM‐DSC Device

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