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Energy Express

  • Editor: Bernard Kippelen
  • Vol. 19, Iss. S4 — Jul. 4, 2011
  • pp: A818–A823
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Development of a high-efficiency laminated dye-sensitized solar cell with a condenser lens

Soochang Choi, Eun-na-ra Cho, Sang-min Lee, Yong-woo Kim, and Deug-woo Lee  »View Author Affiliations


Optics Express, Vol. 19, Issue S4, pp. A818-A823 (2011)
http://dx.doi.org/10.1364/OE.19.00A818


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Abstract

Dye-sensitized solar cells have slightly lower photoelectric efficiency than silicon solar cells. Researchers have investigated various ways to address this problem. In this paper, we found that the optimized separation between the condenser lens and the cells was 8 mm. The cell efficiency increased from 2.5% to 8.3% compared to two isolated cells without a lens. If the efficiency of the basic cell can be increased sufficiently, it should be possible to commercialize the product.

© 2011 OSA

1. Introduction

The dye-sensitized solar cell (DSSC) was developed in 1991 [1

1. B. O'Regan, M. Grätzel, and D. Fitzmaurice, “Optical electrochemistry. I, Steady-state spectroscopy of conduction-band electrons in a metal oxide semiconductor electrode,” Chem. Phys. Lett. 183(1–2), 89–93 (1991). [CrossRef]

] by the Swiss scientist Gratzel, employing a photosensitive dye absorbed onto a thin film of TiO2. DSSCs, which operate using the principle of photosynthesis, have a lower efficiency (of around 10%) than that of silicon solar cells [2

2. M. Grätzel, “Conversion of sunlight to electric power by nanocrystalline dye-sensitized solar cells,” J. Photochem. Photobiol. Chem. 164(1–3), 3–14 (2004). [CrossRef]

5

5. N.-G. Park and K. Kim, “Transparent solar cells based on dye-sensitized nanocrystalline semiconductors,” Phys. Status Solidi 205(8), 1895–1904 (2008). [CrossRef]

]. Efficiency is the ratio between the output energy of the DSSC and the input energy of solar, in energy terms. However, the unit cost is expected to be approximately 20% of that of silicon cells because of the low-cost manufacturing process technologies. Additionally, they have high permeability, and have been identified as the third generation cell to replace silicon solar cells. They can also be applied to glass substrates, making them suitable for applications including car windows.

The crucial weakness of DSSCs is their low conversion efficiency. In order to solve this problem, many studies have been carried out with the aim of increasing the efficiency. The most active research area has focused on increasing the surface area of the TiO2 photo-electrode. Since the dye polymer has a high efficiency when it is absorbed as a molecular monolayer on a semiconductor, the fraction of absorbed sunlight becomes larger as the surface area of the semiconductor with the dye polymer increases. Studies on reducing the size of the TiO2 particles using regular arrays of particles or nanorods, and generating core cell materials with relatively large specific surface areas have been carried out [6

6. M. Law, L. E. Greene, J. C. Johnson, R. Saykally, and P. Yang, “Nanowire dye-sensitized solar cells,” Nat. Mater. 4(6), 455–459 (2005). [CrossRef] [PubMed]

9

9. S. Ngamsinlapasathian, “Highly efficient dye-sensitized solar cell using nanocrystalline titanium containing nanotube structure,” J. Photochem. Photobiol. Chem. 164(1-3), 145–151 (2004). [CrossRef]

]. In addition, since the absorption spectrum of the dye does not cover the whole sunlight spectrum, the efficiency can be increased by developing new dyes and using several dyes with two or three layers [10

10. M. K. Nazeeruddin, A. Kay, I. Rodicio, R. Humphry-Baker, E. Mueller, P. Liska, N. Vlachopoulos, and M. Graetzel, “Conversion of light to electricity by cis-X2bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes,” J. Am. Chem. Soc. 115(14), 6382–6390 (1993). [CrossRef]

].

Although the efficiency of DSSCs is extremely important, improvements in terms of safety and voltage are also important for commercialization. Designing of Z-type series connection, W-type series connection, and parallel-type series connection solar cells with large areas has the same effect as applying series or parallel connections of several individual cells [11

11. Y. Tachibana, J. E. Moser, M. Grätzel, D. R. Klug, and J. R. Durrant, “Subpicosecond Interfacial Charge Separation in Dye-Sensitized Nanocrystalline Titanium Dioxide Films,” J. Phys. Chem. 100(51), 20056–20062 (1996). [CrossRef]

,12

12. S. Ito, T. Takeuchi, T. Katayama, M. Sugiyama, M. Matsuda, T. Kitamura, Y. Wada, and S. Yanagida, “Conductive and Transparent Multilayer Films for Low-Temperature-Sintered Mesoporous TiO2 Electrodes of Dye-Sensitized Solar Cells,” Chem. Mater. 15(14), 2824–2828 (2003). [CrossRef]

]. Indeed, Míguez et al. reported remarkably improved light utilization using one-dimensional photonic crystals of a multilayer coupled inside a cell based on inorganic nanoparticles [13

13. A. Mihi, F. J. López-Alcaraz, and H. Miguez, “Full spectrum enhancement of the light harvesting efficiency of dye sensitized solar cells by including colloidal photonic crystal multilayers,” Appl. Phys. Lett. 88(19), 193110 (2006). [CrossRef]

15

15. G. Lozano, S. Colodrero, O. Caulier, M. E. Calvo, and H. Miguez, “Theoretical analysis of the performance of one-dimensional photonic crystal-based dye-sensitized solar cells,” J. Phys. Chem. C 114(8), 3681–3687 (2010). [CrossRef]

].

2. Purpose of the experiment

Most high-voltage DSSCs have a series or parallel design with a large area. A large area increases the output voltage; however, it also results in a decrease in the efficiency, and it cannot be readily applied to commercial devices. Here, we describe the development of a DSSC that has a high voltage and high efficiency, yet is compact enough to be utilized for real-life applications.

So we developed a vertical array DSSC for a high voltage and high efficiency per unit area by exploiting the biggest advantage of the DSSC: its transparency. And we estimated characteristics of a vertical array DSSC. The main problem of our vertical array DSSC is the permeability of the upper cell; it is necessary to supplement the resulting deficient light source. We solved this problem using a condenser lens.

3. Experimental method

3.1 Fabrication of DSSC

Transparent conducting oxide (TCO) was used for the electrodes, which were made from 2-mm-thick fluorine tin oxide (FTO)-coated glass, and had a sheet resistivity of 7 Ω. TiO2 sol-gel dye paste was used, with N719 dye and An50 electrolyte. 60µm-thick thermoplastic sealants sheet (Dye-sol, Surlyn®) was used to seal the device.

The manufacturing process was as follows. First, organic matter was removed by ultrasonic cleaning in acetone for 30 minutes. The acetone was removed by washing in ethanol for 30 minutes, and the ethanol was removed by washing with distilled water for 30 minutes. The TiO2 paste (Dye-sol, P50) was applied twice using a silk screen and baked in a furnace at 450–500°C for 3–4 hours. After soaking the device in N719 for 12 hours, it was sealed using the thermoplastic sealants sheet and assembled into cells by injecting An50 electrolyte.

We used polydimethylsiloxane (PDMS) blocks to stack individual cells. We could overlay the cells accurately using the blocks so that the active layer was not dispersed.

3.2 Structure of optical system

We constructed a system to improve the efficiency of stacked DSSCs by using a condenser lens. The configuration is shown in Fig. 1 (a) and (b)
Fig. 1 (a) Structure of Optical System. (b) Schematic diagram of the lens system.
. The distance of the stacked devices was 8 mm, which resulted in the highest efficiency of the laminated system. After connecting the two stacked DSSCs in series and using the condenser lens, shown in Fig. 2 (a)
Fig. 2 (a) Shape of the condenser lens. (b) Simulation of the condenser lens
, we measured the change in the efficiency compared with an isolated device. The specifications of the condenser lens are listed in Table 1

Table 1. Specifications of the condenser lens

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. We determined the specifications of the condenser lens using numerical simulation, as shown in Fig. 2 (b). The lens was separated from the DSSC stack by 8 mm. We used a spherical lens on one side only, and it was coated with MgF to reduce reflections. We used polydimethylsiloxane (PDMS) blocks to stack individual DSSCs. We could overlay the cells accurately using the blocks so that the active layer was not dispersed.

4. Results and conclusions

The characteristics of the samples are listed in Table 2

Table 2. Specifications of the condenser lens

table-icon
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. We used DSSCs with efficiencies of 3.1% and 2.9%, corresponding to samples (a) and (b), for the stacked condenser lens system. Sample (a) was stacked on top of sample (b). The configuration is shown in Fig. 3
Fig. 3 IV-curves of a dye-sensitized solar cell sample for experiment
.

4.1 Efficiency as a function of distance from the lens

The results are summarized in Table 3

Table 3. Specifications of the staked DSSC with a condenser lens placed at several distance

table-icon
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. Figure 4
Fig. 4 Simulation of the condenser lens
shows the efficiency as a function of the distance between the condenser lens and the under DSSC. As the distance increased up to 8 mm, the efficiency increased. The efficiency decreased for larger distances because as the distance approached the focal length of the lens, the spot size was reduced so that the active layer could not be fully illuminated. The magnification reached approximately 4 times at a distance of 8 mm; here, the focal length of the lens contained both active layers.

4.2 Cell improvement

We stacked DSSCs using the condenser lens and compared them to two isolated cells without a condenser lens. Figure 5
Fig. 5 Simulation of the condenser lens
show the performance and efficiency of the devices. The results are summarized in Table 4

Table 4. Specifications of the condenser lens

table-icon
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. Various factors characterize the cell performance, including Voc and Isc, which were enhanced. In particular, the efficiency in terms of Voc improved from 2.5% to 8.3%.

5. Conclusion

We used a vertical stacked-cell configuration and a condenser lens to increase the efficiency of DSSCs. We found that the optimized separation between the condenser lens and the cells was 8 mm. The cell efficiency increased from 2.5% to 8.3% compared to two isolated cells without a lens. If the efficiency of the basic cell can be increased sufficiently, it should be possible to commercialize the product. Our highly efficient, high-voltage laminated DSSC is packaged in a module with a lens. Laminating allows a desired voltage to be designed into the device. These cells can be used as power sources in situations where it is difficult to install a generator, or where the solar cell cannot be driven without strong sunlight, as well as for sensors used to monitor high-pressure gases.

Acknowledgments

This work was supported by ERC (ENGINEERING RESEARCH CENTER FOR NET SHAPE & DIE MANUFACTURING) and "Development of Multi-Physics based Micro Manufacturing (MP-M2) Technologies for Biomedical Products" International Collaborative R&D Program project of ministry of knowledge economy.

References and links

1.

B. O'Regan, M. Grätzel, and D. Fitzmaurice, “Optical electrochemistry. I, Steady-state spectroscopy of conduction-band electrons in a metal oxide semiconductor electrode,” Chem. Phys. Lett. 183(1–2), 89–93 (1991). [CrossRef]

2.

M. Grätzel, “Conversion of sunlight to electric power by nanocrystalline dye-sensitized solar cells,” J. Photochem. Photobiol. Chem. 164(1–3), 3–14 (2004). [CrossRef]

3.

M. K. Nazeeruddin, F. De Angelis, S. Fantacci, A. Selloni, G. Viscardi, P. Liska, S. Ito, B. Takeru, and M. Grätzel, “Combined experimental and DFT-TDDFT computational study of photoelectrochemical cell ruthenium sensitizers,” J. Am. Chem. Soc. 127(48), 16835–16847 (2005). [CrossRef] [PubMed]

4.

Y. Chiba, A. Islam, Y. Watanabe, R. Komiya, N. Koide, and L. Han, “Dye-sensitized solar cells with conversion efficiency of 11.1%,” Jpn. J. Appl. Phys. 45(25), 638–640 (2006). [CrossRef]

5.

N.-G. Park and K. Kim, “Transparent solar cells based on dye-sensitized nanocrystalline semiconductors,” Phys. Status Solidi 205(8), 1895–1904 (2008). [CrossRef]

6.

M. Law, L. E. Greene, J. C. Johnson, R. Saykally, and P. Yang, “Nanowire dye-sensitized solar cells,” Nat. Mater. 4(6), 455–459 (2005). [CrossRef] [PubMed]

7.

Y. Diamant, S. G. Chen, O. Melamed, and A. Zaban, “Core-Shell Nanoporous Electrode for Dye Sensitized Solar Cells: the Effect of the SrTiO3 Shell on the Electronic Properties of the TiO2 Core,” J. Phys. Chem. B 107(9), 1977–1981 (2003). [CrossRef]

8.

V. P. S. Perera, P. K. D. D. P. Pitigala, P. V. V. Jayaweera, K. M. P. Bandaranayake, and K. Tennakone, “Dye-Sensitized Solid-State Photovoltaic Cells Based on Dye Multilayer−Semiconductor Nanostructures,” J. Phys. Chem. B 107(50), 13758–13761 (2003). [CrossRef]

9.

S. Ngamsinlapasathian, “Highly efficient dye-sensitized solar cell using nanocrystalline titanium containing nanotube structure,” J. Photochem. Photobiol. Chem. 164(1-3), 145–151 (2004). [CrossRef]

10.

M. K. Nazeeruddin, A. Kay, I. Rodicio, R. Humphry-Baker, E. Mueller, P. Liska, N. Vlachopoulos, and M. Graetzel, “Conversion of light to electricity by cis-X2bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes,” J. Am. Chem. Soc. 115(14), 6382–6390 (1993). [CrossRef]

11.

Y. Tachibana, J. E. Moser, M. Grätzel, D. R. Klug, and J. R. Durrant, “Subpicosecond Interfacial Charge Separation in Dye-Sensitized Nanocrystalline Titanium Dioxide Films,” J. Phys. Chem. 100(51), 20056–20062 (1996). [CrossRef]

12.

S. Ito, T. Takeuchi, T. Katayama, M. Sugiyama, M. Matsuda, T. Kitamura, Y. Wada, and S. Yanagida, “Conductive and Transparent Multilayer Films for Low-Temperature-Sintered Mesoporous TiO2 Electrodes of Dye-Sensitized Solar Cells,” Chem. Mater. 15(14), 2824–2828 (2003). [CrossRef]

13.

A. Mihi, F. J. López-Alcaraz, and H. Miguez, “Full spectrum enhancement of the light harvesting efficiency of dye sensitized solar cells by including colloidal photonic crystal multilayers,” Appl. Phys. Lett. 88(19), 193110 (2006). [CrossRef]

14.

S. Colodrero, A. Mihi, L. Häggman, M. Ocaña, G. Boschloo, A. Hagfeldt, and H. Miguez, “Porous onedimensional photonic crystals improve the power-conversion efficiency of dye-sensitized solar cells,” Adv. Mater. (Deerfield Beach Fla.) 21(7), 764–770 (2009). [CrossRef]

15.

G. Lozano, S. Colodrero, O. Caulier, M. E. Calvo, and H. Miguez, “Theoretical analysis of the performance of one-dimensional photonic crystal-based dye-sensitized solar cells,” J. Phys. Chem. C 114(8), 3681–3687 (2010). [CrossRef]

OCIS Codes
(000.4930) General : Other topics of general interest
(350.6050) Other areas of optics : Solar energy

ToC Category:
Photovoltaics

History
Original Manuscript: April 11, 2011
Revised Manuscript: May 10, 2011
Manuscript Accepted: May 22, 2011
Published: June 9, 2011

Citation
Soochang Choi, Eun-na-ra Cho, Sang-min Lee, Yong-woo Kim, and Deug-woo Lee, "Development of a high-efficiency laminated dye-sensitized solar cell with a condenser lens," Opt. Express 19, A818-A823 (2011)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-S4-A818


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References

  1. B. O'Regan, M. Grätzel, and D. Fitzmaurice, “Optical electrochemistry. I, Steady-state spectroscopy of conduction-band electrons in a metal oxide semiconductor electrode,” Chem. Phys. Lett. 183(1–2), 89–93 (1991). [CrossRef]
  2. M. Grätzel, “Conversion of sunlight to electric power by nanocrystalline dye-sensitized solar cells,” J. Photochem. Photobiol. Chem. 164(1–3), 3–14 (2004). [CrossRef]
  3. M. K. Nazeeruddin, F. De Angelis, S. Fantacci, A. Selloni, G. Viscardi, P. Liska, S. Ito, B. Takeru, and M. Grätzel, “Combined experimental and DFT-TDDFT computational study of photoelectrochemical cell ruthenium sensitizers,” J. Am. Chem. Soc. 127(48), 16835–16847 (2005). [CrossRef] [PubMed]
  4. Y. Chiba, A. Islam, Y. Watanabe, R. Komiya, N. Koide, and L. Han, “Dye-sensitized solar cells with conversion efficiency of 11.1%,” Jpn. J. Appl. Phys. 45(25), 638–640 (2006). [CrossRef]
  5. N.-G. Park and K. Kim, “Transparent solar cells based on dye-sensitized nanocrystalline semiconductors,” Phys. Status Solidi 205(8), 1895–1904 (2008). [CrossRef]
  6. M. Law, L. E. Greene, J. C. Johnson, R. Saykally, and P. Yang, “Nanowire dye-sensitized solar cells,” Nat. Mater. 4(6), 455–459 (2005). [CrossRef] [PubMed]
  7. Y. Diamant, S. G. Chen, O. Melamed, and A. Zaban, “Core-Shell Nanoporous Electrode for Dye Sensitized Solar Cells: the Effect of the SrTiO3 Shell on the Electronic Properties of the TiO2 Core,” J. Phys. Chem. B 107(9), 1977–1981 (2003). [CrossRef]
  8. V. P. S. Perera, P. K. D. D. P. Pitigala, P. V. V. Jayaweera, K. M. P. Bandaranayake, and K. Tennakone, “Dye-Sensitized Solid-State Photovoltaic Cells Based on Dye Multilayer−Semiconductor Nanostructures,” J. Phys. Chem. B 107(50), 13758–13761 (2003). [CrossRef]
  9. S. Ngamsinlapasathian, “Highly efficient dye-sensitized solar cell using nanocrystalline titanium containing nanotube structure,” J. Photochem. Photobiol. Chem. 164(1-3), 145–151 (2004). [CrossRef]
  10. M. K. Nazeeruddin, A. Kay, I. Rodicio, R. Humphry-Baker, E. Mueller, P. Liska, N. Vlachopoulos, and M. Graetzel, “Conversion of light to electricity by cis-X2bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) charge-transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes,” J. Am. Chem. Soc. 115(14), 6382–6390 (1993). [CrossRef]
  11. Y. Tachibana, J. E. Moser, M. Grätzel, D. R. Klug, and J. R. Durrant, “Subpicosecond Interfacial Charge Separation in Dye-Sensitized Nanocrystalline Titanium Dioxide Films,” J. Phys. Chem. 100(51), 20056–20062 (1996). [CrossRef]
  12. S. Ito, T. Takeuchi, T. Katayama, M. Sugiyama, M. Matsuda, T. Kitamura, Y. Wada, and S. Yanagida, “Conductive and Transparent Multilayer Films for Low-Temperature-Sintered Mesoporous TiO2 Electrodes of Dye-Sensitized Solar Cells,” Chem. Mater. 15(14), 2824–2828 (2003). [CrossRef]
  13. A. Mihi, F. J. López-Alcaraz, and H. Miguez, “Full spectrum enhancement of the light harvesting efficiency of dye sensitized solar cells by including colloidal photonic crystal multilayers,” Appl. Phys. Lett. 88(19), 193110 (2006). [CrossRef]
  14. S. Colodrero, A. Mihi, L. Häggman, M. Ocaña, G. Boschloo, A. Hagfeldt, and H. Miguez, “Porous onedimensional photonic crystals improve the power-conversion efficiency of dye-sensitized solar cells,” Adv. Mater. (Deerfield Beach Fla.) 21(7), 764–770 (2009). [CrossRef]
  15. G. Lozano, S. Colodrero, O. Caulier, M. E. Calvo, and H. Miguez, “Theoretical analysis of the performance of one-dimensional photonic crystal-based dye-sensitized solar cells,” J. Phys. Chem. C 114(8), 3681–3687 (2010). [CrossRef]

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