Research Papers

A Study of Back Electrode Stacked With Low Cost Reflective Layers For High-Efficiency Thin-Film Silicon Solar Cell

[+] Author and Article Information
Tsung-Wei Chang, Chao-Te Liu, Wen-Hsi Lee

Department of Electrical Engineering,
National Cheng Kung University,
Tainan 701, Taiwan

Yu-Jen Hsiao

National Nano Device Laboratories,
Tainan 701, Taiwan

Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING. Manuscript received January 4, 2013; final manuscript received September 25, 2013; published online January 10, 2014. Assoc. Editor: Santiago Silvestre.

J. Sol. Energy Eng 136(3), 031002 (Jan 10, 2014) (6 pages) Paper No: SOL-13-1005; doi: 10.1115/1.4025581 History: Received January 04, 2013; Revised September 25, 2013

In this study, commercially available white paint is used as a pigmented dielectric reflector (PDR) in the fabrication of a low-cost back electrode stack with an Al-doped ZnO (AZO) layer for thin-film silicon solar cell applications. An initial AZO film was deposited by the radio-frequency magnetron sputtering method. In order to obtain the highest transmittance and lowest resistivity of AZO film, process parameters such as sputtering power and substrate temperature were investigated. The optimal 100-nm-thick AZO film with low resistivity and high transmittance in the visible region are 6.4 × 10−3 Ω·cm and above 80%, respectively. Using glue-like white paint doped withTiO2 nanoparticles as the PDR enhances the external quantum efficiency (EQE) of a microcrystalline silicon absorptive layer owing to the doped white particles improving Fabry–Pérot interference (FPI), which raises reflectance and scattering ability. To realize the cost down requirement, decreasing the noble metal film thickness such as a 30-nm-thick silver reflector film, and a small doping particle diameter (D50 = 135 nm) and a high solid content (20%) lead to FPI improvement and a great EQE, which is attributed to improved scattering and reflectivity because of optimum diameter (Dopt) and thicker PDR film. The results indicate that white paint can be used as a reflector coating in low-cost back-electrode structures in high-performance electronics.

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Tanaka, M., Taguchi, M., Matsuyama, T., Sawada, T., Tsuda, S., Nakano, S., Hanafusa, H., and Kuwano, Y., 1992, “Development of New a-Si/c-Si Heterojunction Solar Cells: ACJ-HIT (Artificially Constructed Junction-Heterojunction With Intrinsic Thin-Layer),” Jpn. J. Appl. Phys., Part 1, 31, pp. 3518–3522. [CrossRef]
Lu, W.-L., Huang, K.-C., Yeh, C.-H., Hung, C.-I., and Houng, M.-P., 2011, “Investigation of Textured Al-Doped ZnO Thin Films Using Chemical Wet-Etching Methods,” Mater. Chem. Phys., 127, pp. 358–363. [CrossRef]
Berginski, M., Hüpkes, J. R., Schulte, M., Schöpe, G., Stiebig, H., Rech, B., Wuttig, M., 2007, “The Effect of Front ZnO:Al Surface Texture and Optical Transparency on Efficient Light Trapping in Silicon Thin-Film Solar Cells,” J. Appl. Phys., 101, p. 074903. [CrossRef]
Braig, C., 2011, “Fabry-Pérot Interferometer,” Abbe School of Photonics, Jena, Germany, available at: http://www.yumpu.com/en/document/view/4833543/fabry-perot-abbe-school-of-photonics
Ferry, V. E., Sweatlock, L. A.,Pacifici, D., and Atwater, H. A., 2008, “Plasmonic Nanostructure Design for Efficient Light Coupling Into Solar Cells,” Nano Lett., 8(12), pp. 4391–4397. [CrossRef] [PubMed]
Yue, G., Sivec, L., Owens, J. M., Yan, B., Yang, J., and Guha, S., 2009, “Optimization of Back Reflector for High Efficiency Hydrogenated Nanocrystalline Silicon Solar Cells,” Appl. Phys. Lett., 95, p. 263501. [CrossRef]
Müller, J., Rech, B., Springer, J., and Vanecek, M., 2004, “TCO and Light Trapping in Silicon Thin Film Solar Cells,” Solar Energy, 77, pp. 917–930. [CrossRef]
Rech, B., Repmann, T., van den Donker, M. N., Berginski, M., Kilper, T., Hüpkes, J., Calnan, S., Stiebig, H., and Wieder, S., 2006. “Challenges in Microcrystalline Silicon Based Solar Cell Technology,” Thin Solid Films, 511-512, pp. 548–555. [CrossRef]
Haacke, G., 1977, “Transparent Conducting Coatings,” Annu. Rev. Mater. Sci., 7, pp. 73–93. [CrossRef]
Özgür, U., Alivov, Y. I., Liu, C., Teke, A., Reshchikov, M. A., Doğan, S., Avrutin, V.,Cho, S. J., and Morkoç, H.,2005, “A Comprehensive Review of ZnO Materials and Devices,” J. Appl. Phys., 98, p. 041301. [CrossRef]
Lu, Y. Z. J., Ye, Z., Wang, L., Zhao, B., and Huang, J., 2003, “p-Type ZnO Films Deposited by DC Reactive Magnetron Sputtering at Different Ammonia Concentrations,” Mater. Lett., 57, pp. 3311–3314. [CrossRef]
Cotter, J. E., Hall, R. B., Mauk, M. G., and Barnett, A. M., 1999, “Light Trapping in Silicon-Film Solar Cells With Rear Pigmented Dielectric Reflectors,” Prog. Photovolt: Res. Appl., 7(4), pp. 261–274. [CrossRef]
Hedler, J. E. A., Wachtendorf, Ch., Correia, S., Gutlapalli, R., Messerschmidt, D., and Koitzsch, Ch., 2009, “White Back Reflector On Sputtered Zinc Oxide Back Contact For Micromorph Silicon Thin-Film Solar Modules,” 34th IEEE Photovoltaic Specialists Conference (PVSC), Philadelphia, PA, June 7–12, pp. 001102-001106. [CrossRef]
Berger, O., Inns, D., and Aberle, A. G., 2007, “Commercial White Paint as Back Surface Reflector For Thin-Film Solar Cells,” Sol. Energy Mater. Sol. Cells, 91, pp. 1215–1221. [CrossRef]
Rech, B., and Wagner, H., 1999, “Potential of Amorphous Silicon for Solar Cells,” Appl. Phys. A: Mater. Sci. Process., 69, pp. 155–167. [CrossRef]
Bréchignac, C., Cahuzac, P., Carlier, F., de Frutos, M., Masson, A., Mory, C., Colliex, C., and Yoon, B.,1998, “Size Effects in Nucleation and Growth Processes From Preformed Soft-Landed Clusters,” Phys. Rev. B, 57, pp. 2084–2087. [CrossRef]
Mass, J., Bhattacharya, P., and Katiyar, R., 2003, “Effect of High Substrate Temperature on Al-Doped ZnO Thin Films Grown by Pulsed Laser Deposition,” Mater. Sci. Eng., B, 103, pp. 9–15. [CrossRef]
Meyer, K., Schuller, I. K., and Falco, C. M., 1981, “Thermalization of Sputtered Atoms,” J. Appl. Phys., 52, pp. 5803–5805. [CrossRef]
Lai, K.-C., Wang, J.-H., Lu, C.-H., Tsai, F.-J., Yeh, C.-H., and Houng, M.-P., 2011, “Plasma-Induced TCO Texture of ZnO:Ga Back Contacts on Silicon Thin Film Solar Cells,” Sol. Energy Mater. Sol. Cells, 95, pp. 415–418. [CrossRef]
Levinson, R., Berdahl, P., and Akbari, H., 2005, “Solar Spectral Optical Properties of Pigments—Part I: Model for Deriving Scattering and Absorption Coefficients From Transmittance and Reflectance Measurements,” Sol. Energy Mater. Sol. Cells, 89, pp. 319–349. [CrossRef]


Grahic Jump Location
Fig. 1

(a) Conventional and (b) modified superstrate structures

Grahic Jump Location
Fig. 2

Resistivity results of 100-nm-thick ZnO:Al films deposited at 1 mTorr and various (a) substrate temperatures (RF sputtering power = 90 W) and (b) RF sputtering powers (substrate temperature = 450 °C)

Grahic Jump Location
Fig. 3

Optical transmission spectra of ZnO:Al films sputtered at various (a) substrate temperatures and (b) RF sputtering powers

Grahic Jump Location
Fig. 4

SEM images of 100-nm-thick ZnO:Al thin films sputtered at 1 mTorr, 90 W, and substrate temperatures of (a) 150, (b) 250, (c) 350, and (d) 450 °C

Grahic Jump Location
Fig. 5

Reflectivity as a function of wavelength for samples (a) D135-20, (b) D230-12, (c) D230-15, (d) D230-20, (e) D320-12, and (f) D320-15

Grahic Jump Location
Fig. 6

Haze values for 1200-μm-thick PDR layer with various doping content levels as a function of wavelength

Grahic Jump Location
Fig. 7

EQE spectra of a-Si:H/μc-Si:H thin-film solar cells (a) without PDR layers as standard specimens (Std-A, Std-B, and Std-C). Other specimens with various PDR films coated onto the 30-nm-thick Ag back-contact of (b) Std-A, (c) Std-B, and (d) Std-C.

Grahic Jump Location
Fig. 8

EQE spectra of a-Si:H/μc-Si:H thin-film solar cells (a) without PDR layers as standard specimens (Std-D and Std-E). Other specimens with various PDR films coated onto the 50-nm-thick Ag back-contact of (b) Std-D and (c) Std-E.




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