Cu-rich CuInSe₂solar cells with a Cu-poor surface

Abstract

We study defects in CuInSe 2 (CIS) grown under Cu-excess. Samples with different Cu/In and Se/metals flux ratios were characterized by thermal admittance spectroscopy (TAS), capacitance-voltage measurements (CV) and temperature dependent current voltage measurements (IVT). All samples showed two different capacitance responses, which we attribute to defects with energies around 100 and 220 meV. Plus the beginning of an additional step that we attribute to a freeze-out effect. By application of the Meyer-Neldel rule, the parameters of the two defects can be assigned to two different groups, both lying within the energy region of the so-called 'N1-defect' that has been observed for Cu-poor absorbers.

Electrical Characterization of Defects in Cu-Rich Grown CuInSe2Solar Cells

“…is possible to mitigate this limitation by applying a surface treatment in order to form a Cu-poor layer at the absorber surface [6] [7] [8]. This surface treatment allowed us to produce Cu-rich devices as efficient as our Cu-poor ones [9].…”

A short review on the advancements in electroplating of CuInGaSe2 thin films

“…Furthermore, by depositing a thin In-Se layer, the device efficiency of 13.1% was achieved. Such treatment recovers the open-circuit voltage loss by reducing the interface recombination [50]. These results are promising in the context that compositionally altered Cu-rich devices have the potential to compete in terms of efficiency to the Cu-poor ones.…”

Chalcopyrite compound semiconductors for thin film solar cells

“…It has been long understood that the lower efficiency of Cu-rich solar cells is due to recombination at or near the interface, which limits the open-circuit voltage [64]. This recombination can be suppressed by an In-Se surface treatment [65] or by a potassium treatment [17]. In pure CuInSe 2 solar cells (without Ga) the surface treatment leads to efficiencies of Cu-rich solar cells equal to Cu-poor ones [69], whereas in Ga-containing absorbers the surface treatment leads to an improvement of the open-circuit voltage, but not to a complete recovery of the values obtained in Cu-poor absorbers [66].…”