Publication
SPIE Nanoscience + Engineering 2015
Conference paper

Capturing the effect of long low-temperature anneals on the sub-bandgap defect structure of CZTSSe

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Abstract

In this study, Cu2ZnSn(S,Se)4 (CZTSSe) thin films are subjected to long, low-temperature annealing treatments which have been suggested to bring the material through an a€order/disordera€ transition. The samples are then characterized by intensity-dependence photoluminescence measurements at low temperature. We observe that annealing the films at 150°C for 1 day causes a shift in the sub-band gap (Eg) states towards higher photon energies. One week of annealing appears to result in a similar electronic structure as 1 day of annealing, and therefore the measurements performed after 1 day roughly represents the equilibrium (kinetically-limited) defect structure for this temperature. Importantly, all samples measured in this study display strong recombination through deep states up to ∼330 meV below the band gap. Therefore, while some improvements are observed to occur after long low-temperature annealing, we find that this approach does not fully remedy the band tailing states found to limit the Voc in CZTSSe thin film photovoltaics.

Date

09 Aug 2015

Publication

SPIE Nanoscience + Engineering 2015

Authors

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