Electrospinning of Photocatalytic Electrodes for Dye-sensitized Solar Cells

Summary

The overall goal of this project was to use electrospinning to fabricate a photoanode with improved performance for dye-sensitized solar cells.

Abstract

This work demonstrates a protocol to fabricate a fiber-based photoanode for dye-sensitized solar cells, consisting of a light-scattering layer made of electrospun titanium dioxide nanofibers (TiO₂-NFs) on top of a blocking layer made of commercially available titanium dioxide nanoparticles (TiO₂-NPs). This is achieved by first electrospinning a solution of titanium (IV) butoxide, polyvinylpyrrolidone (PVP), and glacial acetic acid in ethanol to obtain composite PVP/TiO₂ nanofibers. These are then calcined at 500 °C to remove the PVP and to obtain pure anatase-phase titania nanofibers. This material is characterized using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The photoanode is prepared by first creating a blocking layer through the deposition of a TiO₂-NPs/terpineol slurry on a fluorine-doped tin oxide (FTO) glass slide using doctor blading techniques. A subsequent thermal treatment is performed at 500 °C. Then, the light-scattering layer is formed by depositing a TiO₂-NFs/terpineol slurry on the same slide, using the same technique, and calcinating again at 500 °C. The performance of the photoanode is tested by fabricating a dye-sensitized solar cell and measuring its efficiency through J-V curves under a range of incident light densities, from 0.25-1 Sun.

Introduction

Dye-sensitized solar cells (DSSCs) are an interesting alternative to silicon-based solar cells¹ thanks to their low cost, relatively simple manufacturing process, and ease of large-scale production. Another benefit is their potential to be incorporated into flexible substrates, a distinct advantage over silicon-based solar cells². A typical DSSC utilizes: (1) a nanoparticulate TiO₂ photoanode, sensitized with a dye, as a light-harvesting layer; (2) a Pt-coated FTO, used as a counter electrode; and (3) an electrolyte containing a redox couple, such as I^-/I₃^-, placed between the ....

Protocol

1. Precursor Solution Preparation

NOTE: Please consult all relevant material safety data sheets (MSDS) before use. Several of the chemicals used in this procedure are harmful and/or toxic to humans. Nanomaterials may have additional hazards compared to their bulk counterpart. Please use the appropriate safety measures and personal protective equipment.

1. Place 5 g of titanium(IV) n-butoxide, 1 g of polyvinylpyrrolidone (PVP), 1 mL of glacial acetic acid, and 10 mL of absolute ethanol into a sample vial.
2. Use a magnetic stirring plate to mix the solution until it has become homogeneous and no bubbles can be observed.
....

Results

The TiO₂ nanofibers were characterized using SEM, X-ray photoelectron spectroscopy (XPS), and XRD. The nanostructure of the photoanode was characterized using SEM. The performance of the assembled DSSC was tested using a solar simulator and a source measure unit.

The SEM image in Figure 1A shows that the nanofibers synthesized using this protocol have a porous structure and a high aspect .......

Discussion

The methods presented in this work describe the fabrication of efficient nanofibrous photoanodes for photocatalytic devices such as DSSCs. Electrospinning is a very versatile technique for the fabrication of nanofibers, but a certain level of skill and knowledge is required to obtain materials with optimal morphologies. One of the most critical aspects to obtaining good nanofibers is the preparation of the precursor solution: there are some key factors, such as the concentration of the carrier polymer and the choice of t.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
titanium(IV) n-butoxide	Sigma-Aldrich	244112
Polyvinylpyrrolidone	Sigma-Aldrich	437190
glacial acetic acid	Sigma-Aldrich	A6283
Ethanol, absolute	Fisher Scientific	E/0650DF/17
20 mL Sample vials	(any)		(or larger volume)
disposable 21G needle	(any)
P150 grit sandpaper	(any)
disposable 10mL syringe	(any)		(or larger volume)
magnetic stirrer + stirring bar	(any)
PHD 2000 syringe pump	Harvard Apparatus	71-2002	(or any other syringe pump capable of outputting a 1mL/hr flow
Aluminium foil	(any)
Stainless steel collector plate	(custom built)
High Voltage Power Source	Gamma High Voltage Research, Inc	ES30P-10W	(or any other power supply capable of outputting +15 kV
Polycarbonate protective shield	(custom built)
Ceramic crucible	(any)
Muffle furnace	(any)
Titanium dioxide, nanopowder	Sigma-Aldrich	718467
50 mL 1-neck round bottom flasks	(any)
bath sonicator	(any)
Terpineol	Sigma-Aldrich
Rotary evaporator	(any)
FTO glass	Solaronix	TCO30-10/LI
Adhesive tape	(any)
razor blade	(any)
SEM	JEOL	6500F
XRD	PANalytical	X'pert Pro
Titanium Tetrachloride	Sigma-Aldrich	89545
Ruthenizer  535-bisTBA	Solaronix	N719
sealing film	Dyesol	Meltonix 1170-25
Pt-coated FTO	Solaronix	TCO30-10/LI
1-propyl-3-methylimidazolium iodide	Sigma-Aldrich	49637
Iodine	Sigma-Aldrich	207772
benzimidazole	Sigma-Aldrich	194123
3-Methoxypropionitrile	Sigma-Aldrich	65290
Digital source meter	Keithley	2400
Solar Simulator	Abet technologies	10500