An official website of the United States government
This content will become publicly available on September 10, 2025
Polymorphism within the Quasi-One-Dimensional Au 2 MP 2 (M = Tl, Pb, Pb/Bi, and Bi) Series
- PAR ID:
- 10585778
- Publisher / Repository:
- Chemistry of Materials
- Date Published:
- Journal Name:
- Chemistry of Materials
- Volume:
- 36
- Issue:
- 17
- ISSN:
- 0897-4756
- Page Range / eLocation ID:
- 8217 to 8228
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract Bi2SeO2is a promisingn‐type semiconductor to pair withp‐type BiCuSeO in a thermoelectric (TE) device. The TE figure of meritzTand, therefore, the device efficiency must be optimized by tuning the carrier concentration. However, electron concentrations in self‐dopedn‐type Bi2SeO2span several orders of magnitude, even in samples with the same nominal compositions. Such unsystematic variations in the electron concentration have a thermodynamic origin related to the variations in native defect concentrations. In this study, first‐principles calculations are used to show that the selenium vacancy, which is the source ofn‐type conductivity in Bi2SeO2, varies by 1–2 orders of magnitude depending on the thermodynamic conditions. It is predicted that the electron concentration can be enhanced by synthesizing under more Se‐poor conditions and/or at higher solid‐state reaction temperatures (TSSR), which promote the formation of selenium vacancies without introducing extrinsic dopants. The computational predictions are validated through solid‐state synthesis of Bi2SeO2. More than two orders of magnitude increase are observed in the electron concentration simply by adjusting the synthesis conditions. Additionally, a significant effect of grain boundary scattering on the electron mobility in Bi2SeO2is revealed, which can also be controlled by adjusting TSSR. By simultaneously optimizing the electron concentration and mobility, azTof ≈0.2 is achieved at 773 K for self‐dopedn‐type Bi2SeO2. The study highlights the need for careful control of thermodynamic growth conditions and demonstrates TE performance improvement by varying synthesis parameters according to thermodynamic guidelines.more » « less
-
Recently, a zipper two-dimensional (2D) material Bi 2 O 2 Se belonging to the layered bismuth oxychalcogenide (Bi 2 O 2 X: X = S, Se, Te) family, has emerged as an alternate candidate to van der Waals 2D materials for high-performance electronic and optoelectronic applications. This hints towards exploring the other members of the Bi 2 O 2 X family for their true potential and bismuth oxysulfide (Bi 2 O 2 S) could be the next member for such applications. Here, we demonstrate for the first time, the scalable room-temperature chemical synthesis and near-infrared (NIR) photodetection of ultrathin Bi 2 O 2 S nanosheets. The thickness of the freestanding nanosheets was around 2–3 nm with a lateral dimension of ∼80–100 nm. A solution-processed NIR photodetector was fabricated from ultrathin Bi 2 O 2 S nanosheets. The photodetector showed high performance, under 785 nm laser illumination, with a photoresponsivity of 4 A W −1 , an external quantum efficiency of 630%, and a normalized photocurrent-to-dark-current ratio of 1.3 × 10 10 per watt with a fast response time of 100 ms. Taken together, the findings suggest that Bi 2 O 2 S nanosheets could be a promising alternative 2D material for next-generation large-area flexible electronic and optoelectronic devices.more » « less
