Solution-Processed Cu2ZnSn(S,Se)4 Thin-Film Solar Cells Using Elemental Cu, Zn, Sn, S, and Se Powders as Source

Abstract

Solution-processed approach for the deposition of Cu2ZnSn (S,Se)4 (CZTSSe) absorbing layer offers a route for fabricating thin film solar cell that is appealing because of simplified and low-cost manufacturing, large-area coverage, and better compatibility with flexible substrates. In this work, we present a simple solution-based approach for simultaneously dissolving the low-cost elemental Cu, Zn, Sn, S, and Se powder, forming a homogeneous CZTSSe precursor solution in a short time. Dense and compact kesterite CZTSSe thin film with high crystallinity and uniform composition was obtained by selenizing the low-temperature annealed spin-coated precursor film. Standard CZTSSe thin film solar cell based on the selenized CZTSSe thin film was fabricated and an efficiency of 6.4 % was achieved.

Fabrication of Cu2ZnSn(S,Se)4photovoltaic devices with 10% efficiency by optimizing the annealing temperature of precursor films

“…As shown in Fig. 3(a)-(e), more and larger cracks with random distribution 22 can be seen when increasing the temperature, which could be originated from the crystallization induced stress release. 27 And a much clearer SEM image is obtained for higher-temperature treated samples, indicating that removing excess organics could improve the lm conductivity.…”

“…22 The reduction in organics and crystallinity improvement of precursor lms are found to have a signicant inuence on the morphologies of corresponding selenized lms, as shown in Fig. 4(a)-(e).…”

“…As the nucleation and growth behaviors of CZTSSe lms in the selenization process are sensitive to the organic remains, 17 the annealing temperature for the precursor lm needs to be optimized. In terms of previous work about the related solution systems 22,24 and unsafety over 450 C carried out in the glove box, the annealing temperature range of the precursor lm is preliminarily selected from 300 to 450 C. This thermal treatment step is carried out on a hot plate which temperature can be precisely controlled. The mass of samples is found to decrease from 2.4 to 1.8 mg by about 25% mass loss, in good agreement with TGA results (see Fig.…”

“…22 Cu (1.65 mmol), Zn (1.23 mmol), Sn (0.98 mmol), S (4 mmol) and Se (0.4 mmol) were loaded into a 10 mL glass vial. Then, 5 mL 1,2-ethylenediamine and 0.5 mL 1,2-ethanedithiol were added into the glass vial.…”

“…4(f) further shows that the CZTSSe lm has a bilayer structure as the most works reported. 9,22 Below the 800 nm-thick large grains, there is a ne crystal layer with a thickness of about 900 nm. The crystallinity of the selenized lms are further explored by grazing XRD.…”