Random nanowires of nickel doped TiO₂with high surface area and electron mobility for high efficiency dye-sensitized solar cells

Abstract

Mesoporous TiO(2) with a large specific surface area (~150 m(2) g(-1)) is the most successful material in dye-sensitized solar cells so far; however, its inferior charge mobility is a major efficiency limiter. This paper demonstrates that random nanowires of Ni-doped TiO(2) (Ni:TiO(2)) have a dramatic influence on the particulate and charge transport properties. Nanowires (dia ~60 nm) of Ni:TiO(2) with a specific surface area of ~80 m(2) g(-1) were developed by an electrospinning technique. The band gap of the Ni:TiO(2) shifted to the visible region upon doping of 5 at% Ni atoms. The Mott-Schottky analysis shows that the flat band potential of Ni:TiO(2) shifts to a more negative value than the undoped samples. The electrochemical impedance spectroscopic measurements showed that the Ni:TiO(2) offer lower charge transport resistance, higher charge recombination resistance, and enhanced electron lifetime compared to the undoped samples. The dye-sensitized solar cells fabricated using the Ni:TiO(2) nanowires showed an enhanced photoconversion efficiency and short-circuit current density compared to the undoped analogue. The transient photocurrent measurements showed that the Ni:TiO(2) has improved charge mobility compared with TiO(2) and is several orders of magnitude higher compared to the P25 particles.

Electrospun ZnO Nanowire Plantations in the Electron Transport Layer for High-Efficiency Inverted Organic Solar Cells

“…Rationale of using electrospun nanowires is that they can support high electron diffusivity and mobility, which would enhance the charge collection efficiency, and can be tailored by controlling the crystallinity. [32][33][34][35][36] The devices that employed electrospun ZnO nanowires gave up to ~20% higher PCE than control devices that did not employ them. The enhanced PCE resulted from an increase in the fill factor; and therefore, the electrospun ZnO nanowires reduce the charge recombination rate and improve the collection efficiency.…”

Charge transport in zirconium doped anatase nanowires dye-sensitized solar cells: Trade-off between lattice strain and photovoltaic parameters

“…5,14 On the other hand, p-type dopants such as Ni, although lowered the Fermi level of TiO 2 , increased the crystallinity and improved the D n through it. 13 The mechanism of such improvement in D n through increase in crystallinity is from lowering of density of localized energy states occur in the band gap, the occurrence of which is the root cause of poor D n in nanomaterials. 20,21 Although a number of studies have reported that details improved PV performance in Zr doped TiO 2 (Zr:TiO 2 ), 12,22 the mechanism of such improvement is still unclear.…”

The effect of double impurity cluster of Ni and Co in TiO2 bulk; a DFT study

“…This definitely declines the photo activity of Ni/anatase under UV light, albeit the defect states prompt it under the visible light. However, some experimental results reported the more photo-efficiency of Ni/TO 2 than pure TiO 2 under UV condition [11,37]. It may refer to the difference between the crystalline structure of that Ni/TiO 2 and our calculated case such as, the presence of some defect in the bulk e.g.…”