Conventional light trapping techniques are inefficient at the sub-wavelength scale. This is the main limitation for the thickness reduction of thin-film solar cells below 500nm. We propose a novel architecture for broadband light absorption in ultra-thin active layers based on plasmonic nano-cavities and multi-resonant mechanism. Strong light enhancement will be shown numerically for photovoltaic materials such as CIGSe and GaAs. First experiments on ultrathin nano-patterned CIGSe solar cells will be presented.
This study addresses the potential of different approaches to improve the generated current density in ultrathin
Cu(In,Ga)Se2 (CIGSe) based solar cells down to 0.1 μm. Advanced photon management, involving both absorption
enhancement and reflection reduction in the absorber, is studied. In this contribution, the three main approaches used
- The reduction of the CIGSe thickness by chemical etching which combines thickness reduction and smoothing effect
on the absorber.
- Optical management by front contact engineering and by the replacement of the back contact by the "lift-off" of CIGSe
layer from the Mo layer and the deposition of a new reflective back contact.
- Application of plasmonic structures to CIGSe solar cells enabling light confinement at the subwavelength scale.