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Passivation ability of graphene oxide demonstrated by two-different-metal solar cells.

Hsu WT, Tsai ZS, Chen LC, Chen GY, Lin CC, Chen MH, Song JM, Lin CH - Nanoscale Res Lett (2014)

Bottom Line: The study on graphene oxide (GO) grows rapidly in recent years.Graphene oxide has been applied on Si two-different-metal solar cells.The simple chemical process to deposit graphene oxide makes low thermal budget, large-area deposition, and fast production of surface passivation possible.

View Article: PubMed Central - PubMed

Affiliation: Department of Opto-Electronic Engineering, National Dong Hwa University, Hualien, Taiwan, sugey0123@gmail.com.

ABSTRACT
The study on graphene oxide (GO) grows rapidly in recent years. We find that graphene oxide could act as the passivation material in photovoltaic applications. Graphene oxide has been applied on Si two-different-metal solar cells. The suitable introduction of graphene oxide could result in obvious enhancement on the efficiency. The simple chemical process to deposit graphene oxide makes low thermal budget, large-area deposition, and fast production of surface passivation possible. The different procedures to incorporate graphene oxide in Si two-different-metal solar cells are compared, and 21% enhancement on the efficiency is possible with a suitable deposition method.

No MeSH data available.


The schematic structure of the Si two-different-metal solar cell. The work functions of Au and Al are 5.1 and 4.18 eV, respectively, and hence, a built-in potential can be formed.
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Fig1: The schematic structure of the Si two-different-metal solar cell. The work functions of Au and Al are 5.1 and 4.18 eV, respectively, and hence, a built-in potential can be formed.

Mentions: A two-different-metal structure for solar cells[13] was used in this study, because it could be fabricated easily in the laboratory and the passivation effect could be singly investigated on the side without electrodes. Figure 1 shows the schematic structure of the two-different-metal solar cell. The work functions of Au and Al are 5.1 and 4.18 eV, respectively, and hence, a built-in potential can be formed for photovoltaic application. In ref.[13], a thinned thermal SiO2 with high quality was inserted between the metals and Si. A critical high pressure H2O vapor heat treatment was also needed to obtain a satisfied interface. Since we were only interested in the effect of GO, the native oxide (SiO2) was kept instead of the high-quality thermal SiO2. We also found that if the top native oxide was removed, Au and Al might be easily shorted via the path of semiconductor. Hence, the native oxide was kept. Four kinds of cell structures (SiGb1, SiGb2, GbSi, and ConSi) were prepared and compared. The top sides of 1 to 30 Ω-cm p-type CZ Si substrates were evaporated by Al and Au in advance to prepare the sample ‘SiGb1’ and ‘SiGb2’. The difference between SiGb1 and SiGb2 only appeared on the procedures of GO deposition. Before the GO deposition, GO suspension should be prepared. First, graphite oxide was prepared by the modified Hummers method[14]. Subsequently, graphite oxide was added in the DI water and followed by two-step ultrasonication and centrifugation with a procedure similar to those in ref.[15, 16]. After the fist ultrasonication for 30 min, the solution was centrifuged at 4,000 r/min for 30 min. The supernatant was again ultrasonicated for 2 h followed by centrifugation at 10,000 r/min for 15 min. The ultrasonication was performed to exfoliate the GO sheets from graphite-oxide multilayer flakes. The GO sheets were hydrophilic due to their oxygen-containing groups, and the supernatant after centrifugation was dispersed with smaller and thinner flakes. The final supernatant was the GO suspension. The SiGb1 sample was prepared via the dip coating method. The topside-down Si substrate was immersed in the GO suspension for 40 min to coat GO sheets on the side without electrodes (rear side), and it was taken out to dry naturally to obtain the SiGb1 sample. To fabricate the SiGb2 sample, the GO suspension was only dropped on the rear surface of the Si substrate instead of the immersion of the entire substrate. This SiGb2 sample was dried at 70°C on the hot plate. Then, the SiGb2 sample was obtained. In ref.[15], the Si substrates with hydrophilic treatment in the Standard Cleaning 1 (SC1) solution with NH4OH:H2O2:H2O = 1:2:8 before GO deposition could own a dense coverage of GO. We would like to prepare a similar sample with SC1 treatment. However, we found that the electrodes of the cells would exfoliate when immersing in the SC1 solution. Hence, we prepared a sample named as ‘GbSi’, where the Si substrate was SC1 (hydrophilicly) treated in advance. Dip coating and drying of GO suspension were then performed, and electrodes were evaporated finally. A similar two-metal structure without the GO deposition, named as ‘ConSi’, was also fabricated for comparison.Figure 1


Passivation ability of graphene oxide demonstrated by two-different-metal solar cells.

Hsu WT, Tsai ZS, Chen LC, Chen GY, Lin CC, Chen MH, Song JM, Lin CH - Nanoscale Res Lett (2014)

The schematic structure of the Si two-different-metal solar cell. The work functions of Au and Al are 5.1 and 4.18 eV, respectively, and hence, a built-in potential can be formed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493844&req=5

Fig1: The schematic structure of the Si two-different-metal solar cell. The work functions of Au and Al are 5.1 and 4.18 eV, respectively, and hence, a built-in potential can be formed.
Mentions: A two-different-metal structure for solar cells[13] was used in this study, because it could be fabricated easily in the laboratory and the passivation effect could be singly investigated on the side without electrodes. Figure 1 shows the schematic structure of the two-different-metal solar cell. The work functions of Au and Al are 5.1 and 4.18 eV, respectively, and hence, a built-in potential can be formed for photovoltaic application. In ref.[13], a thinned thermal SiO2 with high quality was inserted between the metals and Si. A critical high pressure H2O vapor heat treatment was also needed to obtain a satisfied interface. Since we were only interested in the effect of GO, the native oxide (SiO2) was kept instead of the high-quality thermal SiO2. We also found that if the top native oxide was removed, Au and Al might be easily shorted via the path of semiconductor. Hence, the native oxide was kept. Four kinds of cell structures (SiGb1, SiGb2, GbSi, and ConSi) were prepared and compared. The top sides of 1 to 30 Ω-cm p-type CZ Si substrates were evaporated by Al and Au in advance to prepare the sample ‘SiGb1’ and ‘SiGb2’. The difference between SiGb1 and SiGb2 only appeared on the procedures of GO deposition. Before the GO deposition, GO suspension should be prepared. First, graphite oxide was prepared by the modified Hummers method[14]. Subsequently, graphite oxide was added in the DI water and followed by two-step ultrasonication and centrifugation with a procedure similar to those in ref.[15, 16]. After the fist ultrasonication for 30 min, the solution was centrifuged at 4,000 r/min for 30 min. The supernatant was again ultrasonicated for 2 h followed by centrifugation at 10,000 r/min for 15 min. The ultrasonication was performed to exfoliate the GO sheets from graphite-oxide multilayer flakes. The GO sheets were hydrophilic due to their oxygen-containing groups, and the supernatant after centrifugation was dispersed with smaller and thinner flakes. The final supernatant was the GO suspension. The SiGb1 sample was prepared via the dip coating method. The topside-down Si substrate was immersed in the GO suspension for 40 min to coat GO sheets on the side without electrodes (rear side), and it was taken out to dry naturally to obtain the SiGb1 sample. To fabricate the SiGb2 sample, the GO suspension was only dropped on the rear surface of the Si substrate instead of the immersion of the entire substrate. This SiGb2 sample was dried at 70°C on the hot plate. Then, the SiGb2 sample was obtained. In ref.[15], the Si substrates with hydrophilic treatment in the Standard Cleaning 1 (SC1) solution with NH4OH:H2O2:H2O = 1:2:8 before GO deposition could own a dense coverage of GO. We would like to prepare a similar sample with SC1 treatment. However, we found that the electrodes of the cells would exfoliate when immersing in the SC1 solution. Hence, we prepared a sample named as ‘GbSi’, where the Si substrate was SC1 (hydrophilicly) treated in advance. Dip coating and drying of GO suspension were then performed, and electrodes were evaporated finally. A similar two-metal structure without the GO deposition, named as ‘ConSi’, was also fabricated for comparison.Figure 1

Bottom Line: The study on graphene oxide (GO) grows rapidly in recent years.Graphene oxide has been applied on Si two-different-metal solar cells.The simple chemical process to deposit graphene oxide makes low thermal budget, large-area deposition, and fast production of surface passivation possible.

View Article: PubMed Central - PubMed

Affiliation: Department of Opto-Electronic Engineering, National Dong Hwa University, Hualien, Taiwan, sugey0123@gmail.com.

ABSTRACT
The study on graphene oxide (GO) grows rapidly in recent years. We find that graphene oxide could act as the passivation material in photovoltaic applications. Graphene oxide has been applied on Si two-different-metal solar cells. The suitable introduction of graphene oxide could result in obvious enhancement on the efficiency. The simple chemical process to deposit graphene oxide makes low thermal budget, large-area deposition, and fast production of surface passivation possible. The different procedures to incorporate graphene oxide in Si two-different-metal solar cells are compared, and 21% enhancement on the efficiency is possible with a suitable deposition method.

No MeSH data available.