Role of Carbon Nanotubes in Dye-Sensitized TiO₂-Based Solar Cells

Abstract

Incorporation of low-dimensional carbon nanostructures such as carbon nanotubes (CNTs) and graphene sheets into the semiconductor electrodes is a common approach to improve the charge collection and photovoltaic performance of dye-sensitized solar cells. In this work, we clarify the role of CNTs in the semiconductor electrodes by investigating and comparing the electronic process in the dye-sensitized TiO2-based photovoltaic devices. The results show that the formed CNT–TiO2 Schottky junction plays a crucial role in the photovoltaic characteristics. According to the thermionic emission theory, the variation of the photocurrent over the voltage of the cells strongly depends on the height of the Schottky barrier. When the output voltage is low, the intrinsic one-dimensional carbon nanostructures can facilitate electron transport. With the voltage of the cell increasing, the energy dissipation on the Schottky junction increases dramatically and CNTs gradually lose the role of electron transport channels. At the high voltage range, however, leakage of electrons via the CNTs becomes predominant. By virtue of the charge transport channels of CNTs, increments of 44% in photocurrent at short-circuit condition and 18.7% in the overall energy conversion are achieved. Our results provide a basic understanding of the role of CNTs in solar energy conversion.

Nitrite ion sensing properties of ZnTiO3–TiO2 composite thin films deposited from a zinc–titanium molecular complex

“…18 Cp 2 Ti(OCH 2 CH 2 OZnEt) 2 19 and Zn 2 Ti 4 (μ 3 -O) 2 (μ 2 -O) 2 (OiPr) 2 (μ 2 -OMc) 10 20 are known and none of these compounds has been employed as CVD precursors for the deposition Zn-Ti ceramic oxides. Our step by step synthesis has resulted in numerous well defined titanium-based heterobimetallic complexes such as [Mn 2 Ti 4 (TFA) 8 (THF) 6 (OH) 4 (O) 2 ]⋅0.4THF, [Ti 4 (dmae) 6 (μ-OH)(μ-O) 6 Cu 6 (2-methylbenzoate) 9 ] 25 ,…”

Fluorescent Carbon Quantum Dots Incorporated into Dye‐Sensitized TiO2 Photoanodes with Dual Contributions

“…[11] Thec omparison of time constantsf or transport and recombination as af unction of the photon flux are shown in Figure6.T he electron-transport times in the CQDs-containing TiO 2 photoanodea re 28 %s horter than that in the reference photoanode,m eaning that the electron trans- www.chemsuschem.org fer is much faster in the CQDs-containing TiO 2 photoanode (Figure 6a). One is that the photons in the region from 380 to 420 nm can be absorbed by the CQDs ands ubsequently convertedi ntoc urrent through energy transfer to N719 as demonstrated in IPCE spectra, which contributes to the photocurrent.T he otherc ontribution is speculated to be the facilitated electron transport in the TiO 2 -based photoanode after CQDsi ncorporation.…”

“…[4] To address the problems of structural disorders and trap defects at the contact between nanoparticles,v arious 1D nanostructured TiO 2 materials have been developed and employed in photoanodest of acilitate electron transport. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Despite promoting electron transport, both the 1D carbon nanotubes and 2D graphene sheets suffer the problem of directional arrangementc ontrol for electron transport owing to their anisotropic structures. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Despite promoting electron transport, both the 1D carbon nanotubes and 2D graphene sheets suffer the problem of directional arrangementc ontrol for electron transport owing to their anisotropic structures.…”

Incorporation of graphene into SnO2 photoanodes for dye-sensitized solar cells

“…In addition, the measured series resistance (R series ) of the TiO 2 -SnO 2 -RGO (0.45) based DSSC was 97.9 Ω, which was ~1.7-fold lower than that of the control cell ( We attribute this η decrease of the DSSCs with higher RGO loading to (i) opacity of the film (see films before dye adsorption in Fig. S3) reducing light absorption and (ii) high catalytic property of RGO, which has been shown to limit the continuous electron transfer at the photoanode [2,21,47].…”