Liquid Flux–Assisted Mechanism for Modest Temperature Synthesis of Large‐Grain BaZrS₃ and BaHfS₃ Chalcogenide Perovskites

Abstract

Chalcogenide perovskites are promising semiconductor materials with attractive optoelectronic properties and appreciable stability, making them enticing candidates for photovoltaics and related electronic applications. Traditional synthesis methods for these materials have long suffered from high‐temperature requirements of 800–1000 °C. However, the recently developed solution processing route provides a way to circumvent this. By utilizing barium thiolate and ZrH2, this method is capable of synthesizing BaZrS3 perovskite at modest temperatures (500–600 °C), generating crystalline domains on the order of hundreds of nanometers in size. Herein, a systematic study of this solution processing route is done to gain a mechanistic understanding of the process and to supplement the development of device quality fabrication methodologies. A barium polysulfide liquid flux is identified as playing a key role in the rapid synthesis of large‐grain BaZrS3 perovskite at modest temperatures. Additionally, this mechanism is successfully extended to the related BaHfS3 perovskite. The reported findings identify viable precursors, key temperature regimes, and reaction conditions that are likely to enable the large‐grain chalcogenide perovskite growth, essential toward the formation of device‐quality thin films.

A Low-Temperature Growth Mechanism for Chalcogenide Perovskites

“…Niu et al also reported the synthesis of BaZrS 3 (and SrZrS 3 ) from BaS/SrS, Zr, and S at 600 °C with the inclusion of I 2 (60 hthough it is unclear if the reaction happens faster). We note that during the review stage of this work, Vincent et al reported a liquid flux-assisted growth mechanism for BaZrS 3 and BaHfS 3 whose results are complementary to that reported herein.…”

Enhancing the optoelectronic properties of solution-processed AgInSe2 thin films for application in photovoltaics

“…We potentially accessed a selenium rich Ag-Se binary alloy liquid flux that helped nucleate and grow large AgInSe 2 grains similar to those reported for other material systems. 39–41 The selenized film has irregularly shaped grains when selenized with regular selenization conditions, as shown in Fig. 3a and b.…”

Chalcogenide Perovskite, An Emerging Photovoltaic Material: Current Status and Future Perspectives

“…So far only BaZrS 3 , [24,93,[108][109] LaYS 3 , [12,96] BaHfS 3 [110] and CaSnS 3 [111] have been realized in thin film form. New techniques such as solution processed moderate temperature synthesis using a single phase molecular precursor, [110,112] liquid flux assisted mechanism, [113] colloidal nanoscale synthesis, [114][115][116] molecular beam epitaxy [117] and post processing techniques need to be explored more for synthesis of chalcogenide perovskite. Low cost solution based techniques for deposition has to be identified in thin film making.…”