Dye-sensitized Solar Cells: Study of Semiconductor Nanocrystal-based Photoanodes and Quasi-solid-state Electrolytes
Date Issued
2012
Date
2012
Author(s)
Lee, Chuan-Pei
Abstract
In this dissertation, the main purposes are to enhance the charge transport in the semiconductor nanocrystal-based photoanodes, and improve the long-term stability of the dye-sensitized solar cells (DSSCs).
In chapter 1, we make a short introduce of DSSCs, and also the completed introductions for semiconductor nanocrystal-based photoanodes of DSSCs and quasi-solid-state DSSCs (QSS-DSSCs). Their history and applications are also discussed here. The experimental section for all of our studies is shown in chapter 2.
In chapter 3, we try to enhance the performance of a DSSC with the incorporation of titanium carbide (TiC) in the titania (TiO2) matrix. It is established that TiC was partially converted into anatase TiO2 when the TiC was sintered at 450 °C. With the incorporation of 3.0 wt% of the TiC in the TiO2 film, the solar-to-electricity conversion efficiency (η) of the cell reached to 7.56% from its value of 6.61% with a bare TiO2 film. “In situ” incorporation of this TiC/anatase TiO2 composite in the commercial TiO2 is considered as the basis for enhanced cell efficiency of the benefited cell.
In chapter 4, a highly efficient ruthenium dye with an alkyl bithiophene group, designated as CYC-B1, is employed as the photosensitizer for a zinc oxide (ZnO)-based DSSC. The DSSC with a ZnO film (designated as ZN20) sensitized with this dye exhibited an η of 4.88%. Further, PMMA spheres with uniform sizes of ca. 300 nm are synthesized and incorporated to template the ZN20 film (designated as PMMA-ZN20); this PMMA-ZN20 film is used as an overlayer on the underlayer ZN20 film to make the photoanode film (ZN20/PMMA-ZN20) of a DSSC; the thus fabricated DSSC shows an η of 5.42%. This efficiency (5.42%) is highest ever for an all ZnO-based DSSC with a ruthenium-based photosensitizer.
In chapter 5, we study on the favorable effects of titanium nitride (TiN) or its thermally-treated version in a polymer-gelled electrolyte for a QSS-DSSC. With an addition of 3 wt% TiN, the η of the DSSC reaches 5.33% from 4.15% of the cell without TiN. X-ray diffraction (XRD) spectra of thermally treated-TiN (tt-TiN) clearly shows the partial conversion of TiN into TiO2 with both anatase and rutile crystal phases. The DSSC with the incorporation of 3 wt% of tt-TiN into its electrolyte shows a further improved η of 5.68%, with reference to the η of TiN-incorporated DSSC. The cell with 3 wt% of tt-TiN also shows unfailing at-rest stability after more than 1,000 h.
In chapter 6, we fabricate a QSS-DSSC by using a room-temperature ionic liquid (IL), 1-propyl-3-methylimidazolium iodide (PMII), and polyaniline-loaded carbon black (PACB) as the composite electrolyte without the addition of iodine. The η of 5.81% is achieved with this type of DSSC. At-rest durability of the QSS-DSSC with PMII/PACB composite electrolyte was studied at 70 °C and shows unfailing durability.
In chapter 7, a solid IL crystal, 1-ethyl-3-methylimidazolium iodide (EMII), employed as a charge transfer intermediate (CTI) to fabricate an all-solid-state DSSC. In addition, single-walled carbon nanotubes (SWCNTs) were incorporated into EMII and achieved a higher η of 1.88%, as compared to that containing bare EMII (0.41%). Moreover, PMII, which acts simultaneously as a co-CTI and crystal growth inhibitor, was used to further improve η. The highest η (3.49%) is achieved using a hybrid SWCNT-binary CTI (EMII/PMII) and shows a durability of greater than 1,000 h.
Subjects
Dye-sensitized solar cells
Ionic liquid
Titanium carbide
Titanium nitride
Long-term stability
Zinc oxide
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-101-D96524014-1.pdf
Size
23.54 KB
Format
Adobe PDF
Checksum
(MD5):561df12f227b65bd1e0b7b6fdbbe013d