News Article
Photovoltaic Model Leads To Improved Devices
A research team at Sheffield Hallam University in the UK has been exploring a range of options for cutting the costs of producing photovoltaic (PV) cells.
A research team at Sheffield Hallam University in the UK has been exploring a range of options for cutting the costs of producing photovoltaic (PV) cells. These include the use of a low-cost electrodeposition method, less reliance on expensive semiconductor materials, and the identification of alternative solar cell devices and manufacturing techniques offering higher conversion efficiencies.
In the past, limited understanding of the scientific principles underlying PV meant that average solar cell efficiencies only improved from 15.9% to 16.5% between 1992 and 2001 for cadmium telluride based solar cells. By formulating a new “model” to describe the photovoltaic activity of CdTe and copper indium gallium di-selenide (CIGS) materials in solar cells, the Sheffield Hallam Team has significantly improved this understanding and produced devices with 18% efficiency. This has opened up the prospect of new solar cells being developed commercially with higher conversion efficiencies than those currently available.
Team leader Dr IM Dharmadasa reports: “We've already applied for two patents and are preparing the final draft of the third patent in connection with our work, but there's a lot more science to be explored that could increase conversion efficiencies to over 20% in the near future”.
The research team included physicists, chemists, material scientists and engineers. Funding of GBP 104,632 has come from the UK Engineering and Physical Sciences Research Council and a further GBP140,000 from the university.
The model is based on the authors experimental work on glass/conducting glass/CdS/CdTe/metal solar cells and other work in the literature (Semiconductor Science Technology, December 2002). The model explains the device behaviour in terms of a combination of a hetero-junction and a large Schottky barrier at the CdTe/metal interface. The researchers believe that the proposed model explains almost all the experimental results more satisfactorily than the currently assumed p-n junction model.
Following new guidelines based on the model, the researchers have fabricated improved devices producing open circuit voltage (Voc) values of more than 600mV, fill factor (FF) values over 0.60 and a short-circuit current density (Jsc) of more than 60mA/cm2 for the best devices.
In the past, limited understanding of the scientific principles underlying PV meant that average solar cell efficiencies only improved from 15.9% to 16.5% between 1992 and 2001 for cadmium telluride based solar cells. By formulating a new “model” to describe the photovoltaic activity of CdTe and copper indium gallium di-selenide (CIGS) materials in solar cells, the Sheffield Hallam Team has significantly improved this understanding and produced devices with 18% efficiency. This has opened up the prospect of new solar cells being developed commercially with higher conversion efficiencies than those currently available.
Team leader Dr IM Dharmadasa reports: “We've already applied for two patents and are preparing the final draft of the third patent in connection with our work, but there's a lot more science to be explored that could increase conversion efficiencies to over 20% in the near future”.
The research team included physicists, chemists, material scientists and engineers. Funding of GBP 104,632 has come from the UK Engineering and Physical Sciences Research Council and a further GBP140,000 from the university.
The model is based on the authors experimental work on glass/conducting glass/CdS/CdTe/metal solar cells and other work in the literature (Semiconductor Science Technology, December 2002). The model explains the device behaviour in terms of a combination of a hetero-junction and a large Schottky barrier at the CdTe/metal interface. The researchers believe that the proposed model explains almost all the experimental results more satisfactorily than the currently assumed p-n junction model.
Following new guidelines based on the model, the researchers have fabricated improved devices producing open circuit voltage (Voc) values of more than 600mV, fill factor (FF) values over 0.60 and a short-circuit current density (Jsc) of more than 60mA/cm2 for the best devices.
