Introducing manganese complexes as redox mediators for dye-sensitized solar cells

Perera, Ishanie Rangeeka; Gupta, Akhil; Xiang, Wanchun; Daeneke, Torben; Bach, Udo; Evans, Richard A.; Ohlin, C. André; Spiccia, Leone

doi:10.1039/c3cp54894e

Cited by 46 publications

(43 citation statements)

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“…Properties of metal(III) β-diketonato complexes [M(R 1 COCHCOR 2 ) 3 ], M = metal and R = pendant β-diketonato side groups such as CH 3 , have been studied with a variety of different techniques including crystallography [1], electrochemistry [2], non-linear refractive measurements [3], UV-Vis spectroscopy [4], and high frequency electron paramagnetic resonance (EPR) [5]. However, characterization of these complexes by means of X-ray photoelectron spectroscopy (XPS) is not well established.…”

Section: Introductionmentioning

confidence: 99%

Properties of Manganese(III) Ferrocenyl-β-Diketonato Complexes Revealed by Charge Transfer and Multiplet Splitting in the Mn 2p and Fe 2p X-Ray Photoelectron Envelopes

et al. 2016

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Abstract:A series of ferrocenyl-functionalized β-diketonato manganese(III) complexes, [Mn(FcCOCHCOR) 3 ] with R = CF 3 , CH 3 , Ph (phenyl) and Fc (ferrocenyl) was subjected to a systematic XPS study of the Mn 2p 3/2 and Fe 2p 3/2 core-level photoelectron lines and their satellite structures. A charge-transfer process from the β-diketonato ligand to the Mn(III) metal center is responsible for the prominent shake-up satellite peaks of the Mn 2p photoelectron lines and the shake-down satellite peaks of the Fe 2p photoelectron lines. Multiplet splitting simulations of the photoelectron lines of the Mn(III) center of [Mn(FcCOCHCOR) 3 ] resemble the calculated Mn 2p 3/2 envelope of Mn 3+ ions well, indicating the Mn(III) centers are in the high spin state. XPS spectra of complexes with unsymmetrical β-diketonato ligands (i.e., R not Fc) were described with two sets of multiplet splitting peaks representing fac and the more stable mer isomers respectively. Stronger electron-donating ligands stabilize fac more than mer isomers. The sum of group electronegativities, Σχ R , of the β-diketonato pendant side groups influences the binding energies of the multiplet splitting and charge transfer peaks in both Mn and Fe 2p 3/2 photoelectron lines, the ratio of satellite to main peak intensities, and the degree of covalence of the Mn-O bond.

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Section: Introductionmentioning

confidence: 99%

Properties of Manganese(III) Ferrocenyl-β-Diketonato Complexes Revealed by Charge Transfer and Multiplet Splitting in the Mn 2p and Fe 2p X-Ray Photoelectron Envelopes

et al. 2016

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“…Chenodeoxycholic acid (1) has been used as an electrolyte additive in n-type DSSCs to decrease interfacial chargerecombination reactions through passivation of the TiO 2 surface. [14] Salvatori et al concluded that molecules of 1 achieve this by forming supramolecular aggregates on the TiO 2 surface, thereby limiting the access of reduced species in the electrolyte. [15] In this study, the addition of 1 increased the J SC value from 6.95 AE 0.20 mA cm À2 to 7.65 AE 0.39 mA cm À2 and the V OC value from 595 AE 6 mV to 645 AE 12 mV (see Table S1 and Figure S6).…”

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confidence: 99%

Application of the Tris(acetylacetonato)iron(III)/(II) Redox Couple in p‐Type Dye‐Sensitized Solar Cells

et al. 2015

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An electrolyte based on the tris(acetylacetonato)iron(III)/(II) redox couple ([Fe(acac) 3 ] 0/1À ) was developed for p-type dye-sensitized solar cells (DSSCs). Introduction of a NiO blocking layer on the working electrode and the use of chenodeoxycholic acid in the electrolyte enhanced device performance by improving the photocurrent. Devices containing [Fe(acac) 3 ] 0/1À and a perylene-thiophene-triphenylamine sensitizer (PMI-6T-TPA) have the highest reported shortcircuit current (J SC = 7.65 mA cm À2 ), and energy conversion efficiency (2.51 %) for p-type DSSCs coupled with a fill factor of 0.51 and an open-circuit voltage V OC = 645 mV. Measurement of the kinetics of dye regeneration by the redox mediator revealed that the process is diffusion limited as the dyeregeneration rate constant (1.7 10 8 m À1 s À1 ) is very close to the maximum theoretical rate constant of 3.3 10 8 m À1 s À1 . Consequently, a very high dye-regeneration yield (> 99 %) could be calculated for these devices.The possibility of achieving high energy conversion efficiencies and low manufacturing costs continues to stimulate interest in dye-sensitized solar cells (DSSCs). [1] In p-type DSSCs, the photocathode consists of a nanostructured p-type semiconductor sensitized with a dye to efficiently capture solar energy. On photoexcitation, the sensitizer injects holes into the valence band of the p-type semiconductor (typically NiO). [2] In other words, electrons flow from the semiconductor valence band to the sensitizer. The oxidized redox mediator then oxidizes the reduced dye molecules back to their original state and injects electrons into the counter electrode. The electrons then flow through the external circuit and enter the device at the working electrode completing the cycle. Energy conversion efficiencies of up to 13 % have been reported for n-type DSSCs [3] whereas p-type DSSCs have reached 1.3 %. [2c] This difference is largely due to drawbacks associated with the electrolytes used to date and the NiO semiconductor. Being highly colored and electrochromic, NiO absorbs a substantial amount of visible light, decreasing the amount of light available for absorption by the sensitizer. [4] Typically, electrolytes based on the I 3 À /I À redox couple have been used as the redox mediator in p-type DSSCs. This limits the open-circuit voltage (V OC ) that can be achieved to approximately 300 mV because of the small energy gap (Figure 1 c) between the redox potential of the I 3 À /I À couple (+ 0.32 V vs. NHE; NHE = normal hydrogen electrode) and the valence band edge of NiO (+ 0.70 V vs. NHE). [5] For these devices a maximum efficiency of 0.61 % has been achieved. [6] Attempts were made to substitute the I 3 À /I À redox mediator with cobalt polypyridyl complexes [7] and disulfide/thiolates, [8] however the device performance could not be improved until [Co(en) 3 ] 3+/2+ (en = 1,2-diaminoethane) was introduced. Devices based on this redox mediator (denoted [Co(en) 3 ]-p-DSSCs) and the PMI-6T-TPA sensitizer (Figure 1 a) have recently reach...

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“…However, the disadvantage of the organic redox couples is their inferior stability. The third type of redox couples is metal complexes with different valence states containing iron (Fe), copper (Cu), nickel (Ni), manganese (Mn), vanadium (V), and/or cobalt (Co) . As promising alternatives to the iodide redox couple, the metal complexes have the merits of a weak absorption of visible light, weak corrosion of metal electrodes, and adjustable redox potentials.…”

Section: Carbon Counter Electrode In the Dye‐sensitized Solar Cellmentioning

confidence: 99%

“…The third type of redox couples is metal complexes with different valence states containing iron (Fe), copper (Cu), nickel (Ni), manganese (Mn), vanadium (V), and/ or cobalt (Co). [56][57][58][59][60][61][62][63] As promising alternatives to the iodide redox couple, the metal complexes have the merits of a weak absorption of visible light, weak corrosion of metal electrodes, and adjustable redox potentials. However, their complicated synthesis and purification processes lead to high costs.…”

Section: Types Of Redox Couples For the Counter Electrodementioning

confidence: 99%

Carbon Counter Electrodes in Dye‐Sensitized and Perovskite Solar Cells

Sun

Zhou

et al. 2019

Adv Funct Materials

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Developing highly effective and stable counter electrode (CE) materials to replace rare and expensive noble metals for dye‐sensitized and perovskite solar cells (DSC and PSC) is a research hotspot. Carbon materials are identified as the most qualified noble metal‐free CEs for the commercialization of the two photovoltaic devices due to their merits of low cost, excellent activity, and superior stability. Herein, carbonaceous CE materials are reviewed extensively with respect to the two devices. For DSC, a classified discussion according to the morphology is presented because electrode properties are closely related to the specific porosity or nanostructure of carbon materials. The pivotal factors influencing the catalytic behavior of carbon CEs are also discussed. For PSC, an overview of the new carbon CE materials is addressed comprehensively. Moreover, the modification techniques to improve the interfacial contact between the perovskite and carbon layers, aiming to enhance the photovoltaic performance, are also demonstrated. Finally, the development directions, main challenges, and coping approaches with respect to the carbon CE in DSC and PSC are stated.

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Introducing manganese complexes as redox mediators for dye-sensitized solar cells

Cited by 46 publications

References 50 publications

Properties of Manganese(III) Ferrocenyl-β-Diketonato Complexes Revealed by Charge Transfer and Multiplet Splitting in the Mn 2p and Fe 2p X-Ray Photoelectron Envelopes

Properties of Manganese(III) Ferrocenyl-β-Diketonato Complexes Revealed by Charge Transfer and Multiplet Splitting in the Mn 2p and Fe 2p X-Ray Photoelectron Envelopes

Application of the Tris(acetylacetonato)iron(III)/(II) Redox Couple in p‐Type Dye‐Sensitized Solar Cells

Carbon Counter Electrodes in Dye‐Sensitized and Perovskite Solar Cells

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