Band‐Edge Engineered Hybrid Structures for Dye‐Sensitized Solar Cells Based on SnO₂ Nanowires

Abstract

In this report, we show for the first time that SnO2 nanowire based dye sensitized solar cells exhibit an open circuit voltage of 560 mV, which is 200 mV higher than that using SnO2 nanoparticle based cells. This is attributed to the more negative flat band potential of nanowires compared to the nanoparticles as determined by open circuit photo voltage measurements made at high light intensities. The nanowires were employed in hybrid structures consisting of highly interconnected SnO2 nanowire matrix coated with TiO2 nanoparticles, which showed an open circuit voltage of 720 mV and an efficiency of 4.1% compared to 2.1% obtained with pure SnO2 nanowire matrix. The electron transport time constants for SnO2 nanowire matrix were an order of magnitude lower and the recombination time constants are about 100 times higher than that of TiO2 nanoparticles. The higher efficiency observed for DSSCs based on hybrid structure is attributed to the band edge positions of SnO2 relative to that of TiO2 and faster electron transport in SnO2 nanowires.

Effect of Au nano-particles on TiO2 nanorod electrode in dye-sensitized solar cells

“…Initial demonstrations of DSSCs were based on dye sensitization of porous nano crystalline semiconductors like TiO 2 . There are numerous studies on the potentials of improving the efficiency of DSSCs by using other semiconducting metal oxides, such as Nb 2 O 5 [3], CeO 2 [4], ZnO [5,6], and SnO 2 [7] and composite oxide materials [8,9].…”

Atomic layer deposition of tin oxide with nitric oxide as an oxidant gas

“…High light absorption is enabled by nanostructures, which provides a large surface area to increase the conversion efficiency of the cells. [6][7][8][9][10][11] The authors recently reported a successful growth of SnO 2 by atomic layer deposition (ALD) at 60-250 o C by using a newly 30 synthesized cyclic amide of Sn(II) (1,3-bis(1,1-dimethylethyl)-4,5-dimethyl-(4R,5R)-1,3,2-diazastannolidin-2-ylidene) and 50 wt.% hydrogen peroxide (H 2 O 2 ). 12 The growth per cycle was as high as 1.8 Å/cycle and the lowest resistivity of ~2×10 -2 ohm·cm was obtained at a growth temperature of 120 o C. In order to get 35 conformal growth of SnO 2 on structures with high aspect-ratios, the growth temperature needed to be lowered to ~60 o C to extend the lifetime of H 2 O 2 molecules diffusing inside narrow features.…”

Energy production and conversion applications of one-dimensional semiconductor nanostructures

“…Remedial core-shell NWs (with a ZnO core and TiO 2 shell) [44] have been used in order to benefi t from the charge transport of the crystalline ZnO NW and surface stability and charge transfer characteristics of the TiO 2 shell, but the approach has so far met with limited success (PCE ≈ 2.1%) [45]. Tin oxide NWs with an atomic layer TiO 2 NPs have been used with greater success, achieving PCE of ~4.1% (V oc = 0.72 V) compared with 2.1% for the pure SnO 2 -NW DSSC [46]. Solar cells employing QD-sensitized ZnO NW solar cells with a similar I 2 /I 3 -redox couple (as in a DSSC) with PCE of 0.4% (V oc = 0.6 V) have been reported [47].…”