Effects of hydrochloric acid treatment of TiO2 nanoparticles/nanofibers bilayer film on the photovoltaic properties of dye-sensitized solar cells

An Integrated Experimental and Theoretical Approach to the Spectroscopy of Organic‐Dye‐Sensitized TiO2 Heterointerfaces: Disentangling the Effects of Aggregation, Solvation, and Surface Protonation

“…Song et al [82] reported an enhancement in photovoltaic performance due to acid treatment, but increasing the acid concentration beyond a certain threshold led to a decrease in photovoltaic efficiency. Seo et al [86] reported the effects of acid treatment on a Ti compact layer between conducting glass and a mesoporous TiO 2 layer, and observed an improvement in device performances.…”

“…[103] To model aggregation behavior on the TiO 2 surface, we considered the monomer and four different dimeric arrangements (see Figure 2) characterized by an increasing average intermolecular distance (decreasing interaction) and going from the closest interacting structure (dim1) to the least interacting structure (dim4). We performed full geometry optimizations of the molecules grafted onto a (101) (TiO 2 ) 82 anatase cluster [104,105] in the gas phase by using the ADF program package [106][107][108] with the PBE exchange-correlation functional [109] and a DZ basis set. TDDFT calculations of the lowest singlet-singlet excitations were then performed in vacuo and in ethanol (C-PCM [100] ) on the protonated structure as cut from the TiO 2 cluster, by using the Gaussian 09 program package with the CAM-B3LYP [102] exchange-correlation functional and a 6-31G* basis set.…”

“…Before moving on to discuss the optical properties of D5-sensitized TiO 2 , we briefly discuss the effects of acid treatment on the TiO 2 layer previously reported in the literature. The application of acid treatments has been investigated for TiO 2 sensitized with both metal-organic dyes [80][81][82][85][86][87][88] and metal-free dyes. [79] In particular, in this Section we focused on hydrochloric acid because is the most used acid and is known to improve the photovoltaic performance of the sensitized TiO 2 layer and modify the titania surface.…”

“…Adsorption of small cations, [77] such as H + and Li + , on nanocrystalline TiO 2 particles is known to effectively down-shift the semiconductor conduction band (CB) edge [78] and leads to reduced photovoltages, but enhanced photocurrents, which possibly results from the increased amount of active sites for dye adsorption (increased dye loading), have also been reported. [79][80][81][82] To rule out effects on the variation in optical response due to possibly different dye-anchoring modes on bare and protonated TiO 2 , an FTIR characterization of both D5-sensitized substrates has been carried out. Density functional theory (DFT) and time-dependent DFT (TDDT) calculations help us to gain deep insights into the peculiar optical response variations of D5-sensitized TiO 2 observed experimentally.…”

Perspective of electrospun nanofibers in energy and environment

“…The power conversion efficiency values of the SnO2/TiO2 core-shell structured DSSCs (~5.11%) were five times higher than that of SnO2 nanotube DSSCs (~0.99%). Song et al (2013a) have prepared TiO2 nanoparticles/nanofibers bilayer film via spin coating and electrospinning. The TiO2 bilayer film with a thickness of about 6.0 μm was composed of anatase TiO2 phase.…”