Final Activity Report Summary - ECHELLE (Electrodeposited chalcopyrite thin film solar cells: high efficiency limits and losses evaluation)
This project involves the headline field of renewable energy, and concerns complex low cost systems from an applied modelling perspective closely tied with identification of characterisation priorities.
The renewable energy concerned is thin film photovoltaic solar cells fabricated by low cost electrodeposition by the CISEL project. This is a joint public sector project between the EDF electricity generating company and the CNRS national research institute program. It is managed a CNRS-EDF department named IRDEP (institute for research and development of photovoltaic energy, founded in 2005).
This Marie Curie fellowship has developed applied models allowing extraction of parameters with minimal user interaction by use of automated robust numerical fitting procedures which were validated by applying them to known synthetic data sets. This has allowed systematic studies of a large number of solar cells required by the variability of the fabrication process. It has allowed characterisation as a function of temperature and illumination intensity, yielding improved quantitative information on loss mechanisms.
A subsequent study of cell loss mechanisms has identified the layer in the solar cells mainly responsible for losses. This is the interface between the CdS buffer layer and the CIS absorber.
A study of the most promising avenues for improvements is suggested and centres on a better understanding of the interface mentioned above, and on doping mechanisms. The technique suggested for addressing this is admittance spectroscopy. Collaboration in this direction has been developed with a partner research laboratory.
Preliminary device structure modifications have been suggested on the basis of a numerical model of the quantum efficiency (QE) of inhomogeneous solar cells with compositional gradients. The model shows qualitatively how these gradients restrict recombination in the interface region, and encourage minority carrier drift which increases the short circuit current.
Future work is suggested involving bandgap engineering, based partly on known results published in the field. It proposes a cell with compositional gradients low enough to reduce recombination without restricting current flow, and with graded doping levels ensuring a relatively low dependence of space charge region width on bias whilst ensuring that the graded bandgap region reducing recombination near the interface remains depleted.
The renewable energy concerned is thin film photovoltaic solar cells fabricated by low cost electrodeposition by the CISEL project. This is a joint public sector project between the EDF electricity generating company and the CNRS national research institute program. It is managed a CNRS-EDF department named IRDEP (institute for research and development of photovoltaic energy, founded in 2005).
This Marie Curie fellowship has developed applied models allowing extraction of parameters with minimal user interaction by use of automated robust numerical fitting procedures which were validated by applying them to known synthetic data sets. This has allowed systematic studies of a large number of solar cells required by the variability of the fabrication process. It has allowed characterisation as a function of temperature and illumination intensity, yielding improved quantitative information on loss mechanisms.
A subsequent study of cell loss mechanisms has identified the layer in the solar cells mainly responsible for losses. This is the interface between the CdS buffer layer and the CIS absorber.
A study of the most promising avenues for improvements is suggested and centres on a better understanding of the interface mentioned above, and on doping mechanisms. The technique suggested for addressing this is admittance spectroscopy. Collaboration in this direction has been developed with a partner research laboratory.
Preliminary device structure modifications have been suggested on the basis of a numerical model of the quantum efficiency (QE) of inhomogeneous solar cells with compositional gradients. The model shows qualitatively how these gradients restrict recombination in the interface region, and encourage minority carrier drift which increases the short circuit current.
Future work is suggested involving bandgap engineering, based partly on known results published in the field. It proposes a cell with compositional gradients low enough to reduce recombination without restricting current flow, and with graded doping levels ensuring a relatively low dependence of space charge region width on bias whilst ensuring that the graded bandgap region reducing recombination near the interface remains depleted.