  Atomic disorder, a widespread problem in compound crystalline materials, is a
imperative affecting the performance of multi-chalcogenide Cu2ZnSn(S, Se)4
(CZTSSe) photovoltaic device known for its low cost and environmental
friendliness. Cu-Zn disorder is particularly abundantly present in CZTSSe due
to its extraordinarily low formation energy, having induced high-concentration
deep defects and severe charge loss, while its regulation remains challenging
due to the contradiction between disorder-order phase transition thermodynamics
and atom-interchange kinetics. Herein, through introducing more vacancies in
the CZTSSe surface, we explored a vacancy-assisted strategy to reduce the
atom-interchange barrier limit to facilitate the Cu-Zn ordering kinetic
process. The improvement in the Cu-Zn order degree has significantly reduced
the charge loss in the device and helped us realize 15.4% (certified at 14.9%)
and 13.5% efficiency (certified at 13.3%) in 0.27 cm2 and 1.1 cm2-area CZTSSe
solar cells, respectively, thus bringing substantial advancement for emerging
inorganic thin-film photovoltaics.
