An example of a DSSC-CIGS tandem solar cell is shown above. The constituent layers and respective layer thickness are shown.

DSSC-CIGC Tandem Solar Cell

An example of a DSSC-CIGS tandem solar cell with identification of constituent layers is shown above. Please click on the image to expand.

Hybrid and Tandem Solar Cells

What are Hybrid and Tandem Solar Cells?

Hybrid and Tandem solar cells are formed by combining elements or layers of different PV technologies to achieve conversion of energy across a wider spectral range. One such example is the combination of a nanocrystalline dye-sensitised solar cell (DSSC) layer on top of a copper indium gallium selenide (CIGS) thin film bottom cell. The advantage of using a DSSC in a tandem cell is that the spectral range over which it absorbs can be easily tuned by altering the dye sensitiser. Therefore within this hybrid cell, high energy photons are absorbed by the DSSC, while lower energy photons (transmitted by the DSSC) are absorbed by the CIGS cell. A second example is the use of quantum dot sensitisers with a wide band-gap titanium dioxide semiconductor, to intercept a wider fraction of the solar radiation. In this hybrid system, nanoparticles of more traditionally thin film material, such as CdSe, can be used. 


What are the challenges for Hybrid and Tandem Solar Cells?

A significant challange effecting tandem solar cells is to ensure that the top layer(s) shows minimal absorption for the lower energy photons that are absorbed by the bottom layer(s). Within the DSSC-CIGS tandem cell introduced above, significant absorption of lower energy photons occur within the DSSC conducting electrode, which is predominantly made from fluorine doped tin oxide (FTO). Therefore a specific challange for this tandem system is to find an alternative conducting electrode that transmits the lower energy photons. Although some alternative transparrant conducting electrodes exist, there have been difficulties combining these materials into the DSSC. Understanding the interaction of excitons at charge separation interfaces is essential for the development of many hybrid and tandem solar cells.  


What are these challenges being addressed by SISER researchers?

Researchers at Heriot-Watt University are investigating novel materials for improving the efficiency of DSSC-CIGS hybrid solar cells. These include alternative materials for the transparent conducting electrode, such as high mobility transparent conducting oxides IMO and ITiO. They are also looking at ways to overcome the challanges of incorporating existing alternative transparant conducting oxides into a DSSC. 

Aberdeen University are investigating the fundamental processes involved in the interaction of charged species and excitons at the interface between a quantum dot narrow band-gap semiconductor and a titanium dioxide wide band-gap seiconductor. Through better understanding these processes, the sensitiser can be modified to improve the conversion efficiency of these devices.


SISER researchers with interest in this area are: Prof. Russel Howe and Dr Neil Robertson.

Full details of all SISER researchers are found on the SISER People Page



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    @article{Silicon nanostructures for third generation photovoltaic solar cells,
    	author = "Conibeer, G. and Green, M. and Corkish, R. and Cho, Y. and Cho, E. C. and Jiang, C. W. and Fangsuwannarak, T. and Pink, E. and Huang, Y. D. and Puzzer, T. and Trupke, T. and Richards, B. and Shalav, A. and Lin, K. L.",
    	title = "Silicon nanostructures for third generation photovoltaic solar cells",
    	journal = "Thin Solid Films",
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    	title = "Modelling of two-and four-terminal thin-film silicon tandem solar cells",
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    @book{3C-SiC as a future photovoltaic material,
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    	title = "3C-SiC as a future photovoltaic material",
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