Fabrication of Sulfur‐Incorporated Bismuth‐Based Perovskite Solar Cells via a Vapor‐Assisted Solution Process

Abstract

Methylammonium (MA) bismuth iodide ((CH3NH3)3Bi2I9) is a promising perovskite material for solar cell application considering the air stability and the nontoxic lead‐free molecular constitution. However, the further improvement of the device performances is prohibited by the wide bandgap (≈2.1 eV) and unsatisfied crystallinity of the (CH3NH3)3Bi2I9 films. Herein, a developed low‐pressure vapor‐assisted solution process (LP‐VASP) method is applied to obtain the sulfur‐incorporated bismuth‐based perovskites films. Due to the presence of sulfur, both the crystal quality and the energy band property are improved effectively in the as‐fabricated lead‐free perovskite films. After a systematic study of the influence of the reaction time on the device performances, the optimized reaction time is found to be 30 min, under which, the sulfur‐incorporated MA3Bi2I9‐2xSx perovskite films exhibit a reduced bandgap of 1.67 eV and a compact morphology. The corresponding optimal PCE reaches 0.152%. This study provides a new way for the incorporation of sulfur in the lead‐free bismuth‐based perovskite solar cells.

From Pb to Bi: A Promising Family of Pb‐Free Optoelectronic Materials and Devices

“…Finally, they achieved the largest PCE in inverted planar structure of 1.15% (Figure d,e). Recently, MA 3 Bi 2 I 9−2 x S x film was fabricated by the low‐pressure vapor‐assisted solution process method . In detail, bismuth ethyl xanthate, Bi(xt) 3 , film was deposited first, then it reacted with MAI vapor under low pressure (10 kPa) at 150 °C.…”

“…Recently, MA 3 Bi 2 I 9−2x S x film was fabricated by the low-pressure vaporassisted solution process method. [113] In detail, bismuth ethyl xanthate, Bi(xt) 3 , film was deposited first, then it reacted with MAI vapor under low pressure (10 kPa) at 150 °C. The resulting MA 3 Bi 2 I 9−2x S x film has a lower bandgap of 1.67 eV after S-incorporation, and the corresponding device has a PCE of 0.15%, as Figure 7f-h shows.…”

“…f-h) Reproduced with permission. [113] Copyright 2019, John Wiley and Sons. www.advancedsciencenews.com oleic acid, which was 110 times higher than that of ligand-free Cs 3 Bi 2 Br 9 quantum dots.…”

0D/2D Mixed Dimensional Lead-Free Caesium Bismuth Iodide Perovskite for Solar Cell Application

“…Bismuth-based perovskite materials seem to be a promising alternative for lead-free perovskites due to their suitable optoelectronic properties, high defect tolerance, less toxicity and good stability towards humidity, light and heat [ 2 , 24 , 25 ]. The effective ionic radius of bismuth is equivalent to that of lead ions .…”

The Enhanced Photovoltaic Performance of Sb2S3 Solar Cells by Thermal Decomposition of Antimony Ethyl Xanthate with Thiourea Doping

“…The weight loss of 64.99% was observed in the temperature range 120-150 C, indicating the decomposition of Sb(xt) 3 . [18] When the temperature reached 250 C, a smaller exothermic and a negligible weight loss of about 5% were observed, which may be caused by sulfur loss during Sb 2 S 3 crystallization. [19] Based on the result of TGA, the spin-coated films were pre-annealed at 140 C to evaporate the solvent and thermally decomposed, followed by the annealing at different temperatures to form crystalline Sb 2 S 3 .…”