Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
Journal Home About Issues in Progress Current Issue All Issues Feature Issues

Enhanced power conversion efficiency of quantum dot sensitized solar cells with near single-crystalline TiO2 nanohelixes used as photoanodes

Seung Hee Lee, Ho Jin, Dong-Yeong Kim, Kyung Song, Sang Ho Oh, Sungjee Kim, E. Fred Schubert, and Jong Kyu Kim

Open Access Open Access

Abstract

Photo-electrodes with tailored three-dimensional nanostructures offer a large enhancement in light harvesting capability for various optoelectronic devices enabled by strong light scattering in the nanostructures as well as improved charge transport. Here we present an array of three-dimensional titanium dioxide (TiO2) nanohelixes fabricated by the oblique angle deposition method as a multifunctional photoanode for CdSe quantum dot sensitized solar cells (QDSSCs). The CdSe QDSSC with a TiO2 nanohelix photoanode shows a 100% higher power conversion efficiency despite less light being absorbed in CdSe QDs when compared with a conventional TiO2 nanoparticle photoanode. We attribute the higher power conversion efficiency to strong light scattering by the TiO2 nanohelixes and much enhanced transport and collection of photo-generated carriers enabled by the unique geometry and near-single crystallinity of the TiO2 nanohelix structure.

© 2014 Optical Society of America

Full Article  |  PDF Article
More Like This
Fabrication of three-dimensionally ordered macroporous TiO2 film and its application in quantum dots-sensitized solar cells

Xiaohui Song, Zinan Ma, Jianping Deng, Xueping Li, Li Wang, Yong Yan, Xiao Dong, Yongyong Wang, and Congxin Xia
Opt. Express 26(18) A855-A864 (2018)

Ligand capping effect for dye solar cells with a CdSe quantum dot sensitized ZnO nanorod photoanode

Xiao Wei Sun, Jing Chen, Jun Ling Song, De Wei Zhao, Wei Qiao Deng, and Wei Lei
Opt. Express 18(2) 1296-1301 (2010)

Enhanced optical absorption of dye-sensitized solar cells with microcavity-embedded TiO2 photoanodes

Da-Wei Liu, I-Chun Cheng, Jian Z. Chen, Hsin-Wei Chen, Kuo-Chuan Ho, and Chin-Cheng Chiang
Opt. Express 20(S2) A168-A176 (2012)

View More...

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (8)
Fig. 1
Fig. 1 (a) Schematic diagram of a QD-sensitized solar cell based on TiO2 nanohelix array. SEM images of the (b) cross-sectional and (inset) top view of the fabricated TiO2 nanohelixes array on a FTO-coated glass substrate showing a very porous structure facilitating the penetration of QDs and electrolyte into the pores.

Download Full Size | PDF

Fig. 2
Fig. 2 X-ray diffraction patterns of an as-deposited (blue trace) and an annealed (red trace) TiO2 nanohelix array on a FTO glass substrate.

Download Full Size | PDF

Fig. 3
Fig. 3 (a) Bright-field TEM image of a bundle of TiO2 nanohelixes. (b) Selected diffraction pattern taken from a region in (a). (c)-(e) Dark-field TEM images formed by selecting the diffraction spots indicated in (b): (c) {101}; (d) {116}; and (e) {101} reflections of TiO2 anatase phase. Scale bars in TEM images: 200 nm. (f) HRTEM image and electron diffraction pattern (inset) taken from one of the grains in an annealed TiO2 nanohelix. Note that (002) plane appears due to double diffraction.

Download Full Size | PDF

Fig. 4
Fig. 4 (a) Low magnification STEM HAADF image of a TiO2 nanohelix loaded with CdSe QDs (bright spots). Different average atomic numbers of CdSe and TiO2 cause different HAADF intensities. The presence of CdSe QDs on TiO2 was further confirmed by an EDS measurement as shown in the inset. (b) HRTEM image of the CdSe QDs that are loaded on a TiO2 nanohelix. The measured lattice spacings of TiO2 (0.34 nm) and CdSe (0.35 nm) are indicated.

Download Full Size | PDF

Fig. 5
Fig. 5 Absorbance of CdSe QDs loaded on a TiO2 nanohelix array layer (red) and TiO2 nanoparticle layer (blue) on FTO/glass substrates.

Download Full Size | PDF

Fig. 6
Fig. 6 The geometry (right) and the simulated electric field distribution (left) at the surface of (a) stacked TiO2 nanoparticles (10nm radius, 30nm period), (b) a TiO2 nanorod (75nm radius, 200nm period), (c) a TiO2 nanotube (70nm inner, 75nm outer radius, 200nm period), and (d) a TiO2 nanohelix (125nm helix radius, 75nm wire radius, 600nm period) on the FTO substrates when x-polarized electromagnetic wave is incident. The periodic boundary condition is imposed along in-plane direction of the FTO in each simulation. Identical scale bar (shown on left side) for the electric field strength is applied to (b), (c) and (d).

Download Full Size | PDF

Fig. 7
Fig. 7 (a) Measured total and specular transmittances of a bare FTO/glass substrate, the 5 μm-thick TiO2 nanoparticle layer, and 5 μm-thick TiO2 nanohelix array layer on a FTO/glass substrate as a function of the wavelength of the incident light. Inset: Schematic diagram of specular and diffuse optical transmission when monochromatic light is normally incident at the bottom of the FTO/glass substrate. (b) Diffuse transmittances of bare FTO coated glass (black solid line), nanoparticle layer film (red dotted line) and nanohelix array film (blue dotted-dashed line) on the FTO coated glass obtained by measuring the total transmittance and specular transmittance as function of wavelength from 400 to 800nm. Photographs of each sample (see inset) clearly show the difference in the amount of light scattering. The spectrum filled in yellow indicates the absorbance of the synthesized CdSe QD solution (right axis). The peak near at 560nm is attributed to absorption by CdSe QDs.

Download Full Size | PDF

Fig. 8
Fig. 8 (a) J-V characteristics of QDSSCs based on a TiO2 nanoparticle photoanode and a TiO2 nanohelix photoanode both having 5μm thickness under the condition of simulated AM 1.5 solar radiation with 100mW/cm2 intensity. (b) Measured electron transport times (left axis) of nanoparticle and nanohelix array based QDSSCs by intensity modulated photocurrent spectroscopy (IMPS) as a function of incident light intensity using a 530nm laser. Diffusion coefficients (Dn, right axis) are calculated from the electron transport times and thickness of each photoanode.

Download Full Size | PDF

Tables (1)

Tables Icon

Table 1 Comparison of Photovoltaic Parameters of QDSSCs Calculated from the J-V Curves in Fig. 8.

View Table
Select as filters
Select Topics Cancel
Top
       
© Copyright 2024 | Optica Publishing Group. All rights reserved, including rights for text and data mining and training of artificial technologies or similar technologies.
Privacy | Terms of Use