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Abstract The field of photovoltaics is revolutionized in recent years by the development of two–dimensional (2D) type‐II heterostructures. These heterostructures are made up of two different materials with different electronic properties, which allows for the capture of a broader spectrum of solar energy than traditional photovoltaic devices. In this study, the potential of vanadium (V)‐doped WS2is investigated, hereafter labeled V‐WS2, in combination with air‐stable Bi2O2Se for use in high‐performance photovoltaic devices. Various techniques are used to confirm the charge transfer of these heterostructures, including photoluminescence (PL) and Raman spectroscopy, along with Kelvin probe force microscopy (KPFM). The results show that the PL is quenched by 40%, 95%, and 97% for WS2/Bi2O2Se, 0.4 at.% V‐WS2/Bi2O2Se, and 2 at.% V‐WS2/Bi2O2Se, respectively, indicating a superior charge transfer in V‐WS2/Bi2O2Se compared to pristine WS2/Bi2O2Se. The exciton binding energies for WS2/Bi2O2Se, 0.4 at.% V‐WS2/Bi2O2Se and 2 at.% V‐WS2/Bi2O2Se heterostructures are estimated to be ≈130, 100, and 80 meV, respectively, which is much lower than that for monolayer WS2. These findings confirm that by incorporating V‐doped WS2, charge transfer in WS2/Bi2O2Se heterostructures can be tuned, providing a novel light‐harvesting technique for the development of the next generation of photovoltaic devices based on V‐doped transition metal dichalcogenides (TMDCs)/Bi2O2Se.
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Optical Properties and Photocarrier Dynamics of Bi 2 O 2 Se Monolayer and Nanoplates
Abstract A comprehensive experimental study on optical properties and photocarrier dynamics in Bi2O2Se monolayers and nanoplates is presented. Large and uniform Bi2O2Se nanoplates with various thicknesses down to the monolayer limit are fabricated. In nanoplates, a direct optical transition near 720 nm is identified by optical transmission, photoluminescence, and transient absorption spectroscopic measurements and is attributed to the transition between the valence and conduction bands in the Γ valley. Time‐resolved differential reflection measurements reveal ultrafast carrier thermalization and energy relaxation processes and a photocarrier recombination lifetime of about 200 ps in nanoplates. Furthermore, by spatially resolving the differential reflection signal, a photocarrier diffusion coefficient of about 4.8 cm2s−1is obtained, corresponding to a mobility of about 180 cm2V−1s−1. A similar direct transition is also observed in monolayer Bi2O2Se, suggesting that the states in the Γ valley do not change significantly with the thickness. The temporal dynamics of the excitons in the monolayer is quite different from the nanoplates, with a strong saturation effect and fast exciton–exciton annihilation at high densities. Spatially and temporally resolved measurements yield an exciton diffusion coefficient of about 20 cm2s−1.
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- Award ID(s):
- 1505852
- PAR ID:
- 10457790
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 8
- Issue:
- 6
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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