Revealing the Role of Potassium Treatment in CZTSSe Thin Film Solar Cells.


Li W, Su Z, Tan JMR, Chiam SY, Seng HL, Magdassi S, Wong LH. Revealing the Role of Potassium Treatment in CZTSSe Thin Film Solar Cells. Chem. Mater.Chemistry of Materials. 2017 :Ahead of Print.

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Potassium (K) post-treatment on CIGSSe has been shown to yield the highest efficiency reported to date. However, very little is known on the effect of K doping in CZTSSe and the mechanism behind the efficiency improvement. Here we reveal the mechanism by which K enhances the charge sepn. in CZTSSe. We show that K accumulates at the CdS/CZTSSe, passivating the recombination at the front interface and improving carrier collection. K is also found to accumulate at the CZTSSe/Mo interface and facilitates the diffusion of Cd into the absorber which affects the morphol. and grain growth of CZTSSe. As revealed by the C-V, external quantum efficiency, and color J-V test, K doping significantly increases the carrier d., improves carrier collection, and passivates the front interface and grain boundaries, leading to the enhancement of Voc and Jsc. The av. power conversion efficiency has been promoted from 5% to above 7%, and the best 7.78% efficiency has been achieved for the 1.5 mol % K-doped CZTSSe device. This work offers some new insights into the K doping effects on CZTSSe via soln.-based approach and demonstrates the potential of facile control of K doping for further improvement of CZTSSe thin film solar cells. [on SciFinder(R)]


CAPLUS AN 2017:671749(Journal)