Mechanochemically Synthesized SnS Nanocrystals: Impact of Nonstoichiometry on Phase Purity and Solar Cell Performance

Abstract

We demonstrate nontoxic, earth-abundant lightabsorbing SnS thin films fabricated by a low-cost, environmentally friendly nonvacuum process. SnS nanocrystals (NCs) are mechanochemically synthesized from elemental powders without the use of any other additives or solvents. To investigate the effect of the Sn-to-S stoichiometric ratio on the crystalline phase of the SnS NCs, the nonstoichiometry is systematically controlled from 0.95 (Sn 0.95 S) to 1.05 (Sn 1.05 S) by adjusting the mixing ratio of the Sn and S powders. The crystallographic evolution with the milling time signifies that the formation of the SnS phase follows a mechanochemically driven self-propagation reaction mechanism. The as-synthesized SnS NCs with a stoichiometric composition (i.e., Sn 1.00 S) are found to contain a Sn 2 S 3 impurity phase in a nonnegligible amount, which can be subsequently eliminated by a post heat treatment at 500 °C in a reducing atmosphere. Interestingly, however, the formation of Sn 2 S 3 during the mechanochemical synthesis process is greatly alleviated by introducing a Sn-excess composition (e.g., Sn 1.05 S). In addition, the solar cell with a Sn 1.05 S absorber exhibits a much higher efficiency as compared to the Sn 0.95 S-or Sn 1.00 S-based devices, which is likely attributed to the improved phase purity of Sn-excess SnS as well as to its better microstructure with higher crystallinity than the other compositions.

Emerging BaZrS3 and Ba(Zr,Ti)S3 Chalcogenide Perovskite Solar Cells: A Numerical Approach Toward Device Engineering and Unlocking Efficiency

“…To overcome this, Steinmann et al reported that annealing SnS for 1 h under vacuum conditions (15 m Torr) at 500 °C or in an Ar or H 2 gas atmosphere at ambient temperature prevents the formation of impurity phases . Moreover, introducing Sn excess composition (Sn 1.05 S) during the synthesis process significantly reduces the formation of Sn 2 S 3 without additional thermal processing . In summary, the methods and strategies proposed have the potential to significantly benefit the PV community by enabling them to fabricate highly efficient BaZrS 3 -based devices as technology advances.…”

“… 110 Moreover, introducing Sn excess composition (Sn 1.05 S) during the synthesis process significantly reduces the formation of Sn 2 S 3 without additional thermal processing. 111 In summary, the methods and strategies proposed have the potential to significantly benefit the PV community by enabling them to fabricate highly efficient BaZrS 3 -based devices as technology advances.…”

Multiple Roles of 1,4-Diazabicyclo[2.2.2]octane in the Solvothermal Synthesis of Iodobismuthates

“…For insoluble compounds, which cannot be deposited from a solution, spin coating from suspensions is a viable alternative. This has been demonstrated for the construction of solar cells, using SnS 51 or Cu(In,Ga)Se 2 , 52 and requires the optimization of the suspension used for spin coating by exploring the use of ultrasonication or wet milling to improve the dispersion of the solid into the suspension. This work is beyond the scope of this paper.…”

Magnetic grinding synthesis of copper sulfide-based photocatalytic composites for the degradation of organic dyes under visible light

“…For example, Park et al synthesized SnS nanocrystals by planetary ball milling method and explored their performance and application as thin film solar cells. 31 These traditional ball milling methods have been studied and applied in the preparation of metal sulfides, but the conversion rate of sulfide prepared from simple substances is not high and the preparation process takes a long time due to the limitation of the grinding medium and grinding equipment.…”