| Electrochemical characterization of binuclear ruthenium (II) complex towards application in efficient Dye Sensitized Solar Cell (DSSC) |
| کد مقاله : 1100-CNF |
| نویسندگان: |
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بابک نعمتی * گروه شیمی معدنی، دانشکده شیمی، دانشگاه بوعلی سینا، همدان، ایران |
| چکیده مقاله: |
| Dye-sensitized solar cells (DSSCs) have emerged as efficient and promising alternative to conventional Si-based and thin-film photovoltaic technologies because of their low cost and high-power conversion efficiencies [1]. Since light-harvesting is the key process in the DSSC device, much effort has been devoted to increasing the absorptivity of the dyes [1, 2]. The polypyridyl ruthenium (II) complex-based dyes have remarkable performance originating from their strong absorption in the visible region and chemical stability of photoexcited states, and oxidized form [2]. Herein, the new binuclear ruthenium (II) complex (BiRu Dye) with an alkyl spacer (-CH2-) was designed and synthesized and in order to obtain insight into potential of this complex for used as dye in DSSC, its electrochemical properties were investigated and compared with N3 (Ru(H2dcbpy)2(NCS)2) as standard dye. The cyclic and DPV voltammograms of binuclear ruthenium (II) dye are shown in Figure 1. BiRu in DMF exhibited a quasi-reversible oxidative process at E1/2 = 0.81 V which is attributed to a Ru III/II couple [3]. The half-wave oxidation potential of BiRu dye is shifted negatively by 0.05 V compared to the N3 couple, [3] indicating stronger electron-donating ability of phenanthroimidazole bridging ligand than H2dcbpy. In the cathodic region, several irreversible and quasi-reversible reduction peaks at -1.02 V to -1.65 V were observed, which can be assigned to the reduction of H2dcbpy and phenanthroimidazole bridging ligand. The calculated excited state oxidation potential (E* = -1 V, see table 1) for BiRu dye is close to N3 dye and sufficiently more negative than the conduction band edge level of the TiO2 at approximately -0.7 V [4] indicating energically highly favorable for electron injection from the excited dyes into the conduction band of TiO2. Moreover, the estimated LUMO energy of BiRu dye (-3.26 eV) is higher than the conduction band energy level of the TiO2 (-4.0 eV) which is desirable for more efficient electron injection into conduction band of TiO2. Comparison of integrated area under the oxidation and reduction peaks of differential pulse voltammogram (DPV) for D1 with one-electron oxidation couple of ferrocene showed that the binuclear complex underwent quasi-reversible two-electron oxidation process which is indicating that, there is no electronic communication between the two identical Ru (II) centers and therefore there is no negative effect on the electronic properties of dye cores. In light of results obtained from the electrochemical data, the performance of DSSC device based on BiRu was evaluated and compared with N3 as standard dye. The obtained results shown that the performance of DSSC device based on BiRu is higher than N3 which is attributed to the higher absorption coefficient in the visible region and lower E1/2 of BiRu. Moreover, the improved JSC and VOC were caused by the avoided aggregation of BiRu dye, because of its bulky structure which could decrease the recombination and intermolecular charge transfer [5]. In conclusion, we designed and synthesized new binuclear ruthenium sensitizers, BiRu, by incorporating thiophene antennas into the ancillary ligands and investigated its potential as dye by CV and DPV techniques. The improvement of performance of DSSC device based on BiRu reveal the great potential of this dye for DSSC application in the future |
| کلیدواژه ها: |
| Cyclic voltammetry, Differential pulse voltammetry, Binuclear ruthenium (II) sensitizer, Dye sensitized solar cell. |
| وضعیت : چکیده برای ارائه به صورت پوستر پذیرفته شده است |