Test of Different Sensitizing Dyes in Dye-Sensitized Solar Cells Based on Nb2O5 Photoanodes

Abstract

High-performance dyes routinely employed in TiO 2 -based dye-sensitized solar cells (DSSCs) were tested in cells assembled using Nb 2 O 5 nanostructure-based photoanodes. The sensitizers were chosen among both metal-complex (two Ru-based, N749 and C106, and one Zn-based dye, DNF12) and metal-free organic dyes (DNF01, DNF11 and DNF15). Two different sensitization processes were performed: the one commonly used for TiO 2 photoanodes, and a new process relying on high pressure by autoclavation. The assembled cells were characterized by current density-voltage (J-V) curves under air mass (AM) 1.5 G illumination and in the dark, incident photon-to-current efficiency (IPCE) measurements, and electrochemical impedance spectroscopy. The tested cells show different proportional efficiencies of the dyes under investigation for Nb 2 O 5 -and TiO 2 -based devices. Furthermore, the results were compared with those obtained in our previous work using N719 anchored on Nb 2 O 5 . A remarkable efficiency value of 4.4% under 1 sun illumination was achieved by coupling the C106 dye with a nonvolatile electrolyte. This value is higher than the one attained under the same conditions by using N719.

Enhanced photoelectrochemical performance of TiO2 nanorod array films based on TiO2 compact layers synthesized by a two-step method

“…The only (002) strong diffraction peak also proves that the TiO 2 nanorods grow in the [001] direction with the growth axis parallel to the substrate surface normal. 27,29 For TCL 5 , TCL 10 and TCL 20 , the intensity of the (002) peak of TNA lms gradually increases; however, for TCL 30 , it is the same as that for TCL 20 . This shows that the increasing thickness of TCLs can improve the crystallization performance of TiO 2 to a certain extent and promote the better oriented crystallization growth of TiO 2 nanorods.…”

“…1c) are closely connected with each other, uniform and compact, orderly arranged and without fragmentation, which indicates the good crystal integrity of TiO 2 nanorods and has a positive effect on the reduction of crystal defects in the TNA lms. Furthermore, the combined action of dense TNA lms and TCL 20 in DSSCs can effectively prevent the direct contact between the conductive layer of FTO and the redox electrolyte to reduce the dark current. 28 In Fig.…”

“…2a) and good morphology (Fig. 1c) of TNA lms grown over TCL 20 show that the lowest PL strength benets from the well-crystallized TiO 2 nanorod crystal. In addition, according to the position and intensity analysis of the PL peaks, the PL peak at 423.5 nm is the bound exciton peak with weak intensity, and the PL peak at 455 nm is its phonon peak.…”

“…17 and 18) and Nb 2 O 5 . 19,20 As a typical wide-band gap transition metal oxide semiconductor (MOS) material, TiO 2 has excellent physical and chemical properties. TiO 2 with its high chemical stability, appropriate band gap, good photoelectric conversion performance, excellent charge separation and transmission capacity, as well as low-price, non-toxicity and abundant reserves, has always been the research emphasis for electron transport layer materials.…”

Optical properties of dye DN-F01 as sensitizer

“…(Lee et al, 2017) In DSSC, dye as a sensitizer plays a key role in absorbing sunlight and converting solar energy into electrical energy (Oviri & Ekpunobi, 2013). Dye has several conditions to be apply to the DSSC, such as the absorption spectrum must cover the entire visible region including the near-infrared region (NIR), the dye must have a holding group to bind it to the semiconductor surface, an oxidation state that is more positive than the redox potential of the electrolyte, the potential of the Highest Occupied Molecular Orbital (HOMO) dye must be positive enough compared to the potential redox electrolyte for efficient dye regeneration, the potential of the lowest Unoccupied Molecular Orbital (LUMO) dye must be negative enough to match the potential edge of the semiconductor conduction band and its orbitals must be placed in the acceptor's lowest dyes to provide efficient electron injection (Hagberg et al, 2017;Husain et al, 2018;Latini, 2018).…”