Tale of Two Bismuth Alkylthiolate Precursors’ Bifurcating Paths in Chemical Vapor Deposition

We report on the application of two bismuth alkylthiolates, Bi(SR) 3, differing only with respect to the alkyl substituents (R = −Bu t ( 1a ); −Pr i ( 1b )) in the chemical vapor deposition (CVD) process as single-source precursors for both Bi 2 S 3 and Bi. Despite similar structural chemistry and chemical composition, the minor differences in the polarity of the bonds in Bi–S–C units in ( 1a ) and ( 1b ) resulted in strikingly different results in their low-temperature (250 °C) decomposition. Whereas the CVD of Bi(SBu t ) 3 produced single-crystalline Bi 2 S 3, elemental Bi was obtained from Bi(SPr i ) 3 . The CVD deposits in both cases were unambiguously identified as Bi 2 S 3 and Bi, as verified by X-ray diffraction (XRD) analysis, high-resolution X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The highly oriented and uniformly shaped two-dimensional (2D) Bi 2 S 3 platelets were found to be single crystalline by selected area electron diffraction (SAED) performed during high-resolution transmission electron microscopy (HRTEM) and correlative 2D-SEM–Raman spectroscopy. The photoconductivity of Bi 2 S 3 deposited on fluorine-doped tin oxide (FTO) was characterized by white light illumination that indicated the repetitive release of photoexcited charge carriers from deep-level defects.