One-Step Rapid Deposition of Bi₂S₃ Thin Film and Comprehensive Study of Its Photoelectrochemical Activity

Abstract

Achieving the synthesis of bismuth sulfide (Bi2S3) thin films with high crystallinity and controllable morphology via simple and energy-saving deposition processes is highly desired. A novel, green, and open-air pressure solution-based deposition technique was developed to prepare horizontally orientated Bi2S3 thin films by applying less toxic and commercially available BiCl3 and thiourea as precursors. The deposition time was effectively shortened to the minute level via controlling the mixing mode of the precursors. The crystallinity and surface morphology of Bi2S3 were highly dependent on the synthesis temperatures. Bi2S3 thin films synthesized at a moderate temperature of 450 °C possessed a continuous surface with high crystallinity and exhibited superior photoelectrochemical performance with a high photocurrent density of 2.6 mA/cm2 at 0.6 V vs Ag/AgCl. The promising photoelectrochemical performance can be attributed to the high transfer efficiency of photogenerated electron–hole pairs owing to the small interfacial resistance and long lifetime of photogenerated carriers.

Mist Chemical Vapor Deposition of Bi13S18I2 for Photoelectrochemical-type Photodetection

“…The directtype band gap was determined as 0.8 eV, which was much narrower than the Bi 2 S 3 . 25 As shown in Figure S8, the M−S plot possessed a positive slope, suggesting the n-type character of Bi 13 S 18 I 2 . Similarly, in the PEC measurement, anodic current was observed.…”

“…Raman spectra of the thin films synthesized at 300 and 350 °C were well consistent with the previous reports that the peaks arising from the A g phonon (67, 95, and 210 cm –1 ) and B 1g phonon (270 cm –1 ) stretching modes of Bi–S vibration were observed. , At 400 °C, Raman peaks located at 95 and 270 cm –1 shifted to a higher frequency, which might reflect the change in preferred orientation. The additional Raman peak that appeared at around 130 cm –1 was attributed to the small content of Bi 2 S 3 . Based on the above results, the detailed deposition mechanism can be simply summarized as follows: at first, the independent atomized mist containing BiI 3 and thiourea molecules was mixed completely in the mixing cylinder.…”

“…Bi 13 S 18 I 2 synthesized at optimal temperature showed a broad absorbance between 300 and 1500 nm (Figure a), where the absorbance A was calculated via A = − ln 0.25em T 1 − R . The direct-type band gap was determined as 0.8 eV, which was much narrower than the Bi 2 S 3 . As shown in Figure S8, the M–S plot possessed a positive slope, suggesting the n -type character of Bi 13 S 18 I 2 .…”

“…The derivation of nanorods’ size was mainly determined by the nucleation and growth rate of nanorods, while it is also influenced by the preferred orientated growth of Bi 13 S 18 I 2 as discussed above. At 400 °C, additional observed nanowires might correspond to the formation of Bi 2 S 3 …”

Highly Sensitive and Stable Visible-Light Self-Power Photodetectors Based on Solution-Processed Bi4O5I2

“…As shown in Figure b, an emission peak centered at around 550 nm, which was attributed to the band-band intrinsic transition. In addition, the lifetime of the excited state was determined as 4.6 ns, derived from the fitting of the decay curves with monoexponential functions (Figure S6), which was slightly longer than those of BiOCl and Bi 2 S 3 . , The longer lifetime guaranteed enough time for the transition from singlet state to the triplet state, which was beneficial for the PEC photodetection performance.…”