Chemical Composition Dependence of Cu₂ZnSnS₄ Absorbers Fabricated by Sulfurization of Thermal Evaporated Metal Precursors and Solar Cell Performance

Abstract

We investigate the synthesis of kesterite Cu2ZnSnS4 (CZTS) thin films using thermal evaporation from copper, zinc and tin pellets and post-annealing in a sulfur atmosphere. The effects of chemical composition were studied both on the absorber layer properties and on the final solar cell performance. It is confirmed that CZTS thin film chemical composition affects the carrier concentration profile, which then influences the solar cell properties. Solar cells using a CZTS thin film with composition ratio Cu/(Zn+Sn) = 0.87, and Zn/Sn = 1.24 exhibited an open-circuit voltage of 483 mV, a short-circuit current of 14.54 mA/cm2, a fill factor of 37.66 % and a conversion efficiency of 2.64 %. Only a small deviation from the optimal chemical composition can drop device performance to a lower level, which confirms that the CZTS solar cells with high conversion efficiency existed in a relatively narrow composition region.

Novel Evaporation Process for Deposition of Kesterite Thin Films Synthesized by Solvothermal Method

“…In the present work are reported CZTS compounds synthesized by using the solvothermal method and deposited over a substrate by thermal evaporation. Usually, thermal evaporation is applied using elemental metals in a sulphur atmosphere [11,12]. To the best of our knowledge, the present paper reports for the rst time a CZTS compound applied directly through thermal evaporation without a sulfurized vapor lling the atmosphere.…”