WAP Research Lab
Laboratory of Hybrid Organic-Inorganic Semiconductors
Dr. Watcharaphol (Oat) Paritmongkol
School of Molecular Science and Engineering, VISTEC
Metal Organochalcogenides (MOCs)
MOCs are an emerging class of hybrid organic-inorganic semiconductors that combine the robustness of inorganic materials with the fabrication convenience and tunability of organic semiconductors. They adopt the [M(ER)]n formula, where M is a metal, E = S, Se, Te, and R is an organic hydrocarbon. In these materials, metal and organochalcogenide units are linked by covalent metal-chalcogen bonds, forming various extended structures. What makes MOCs particularly interesting are their their exceptional properties, including strong luminescence, high chemical stability, non-toxic chemical composition, unique light-matter interactions, anisotropy, and scalable synthesis methods.
In our lab, we aim to lead in this field. Our research in this direction involves:
Materials design by organic modification and inorganic tuning,
Synthesis development to produce defect-free crystals and nanomaterials,
Physical studies of their charge carriers, and
Exploration of their applications in light-emitting diodes (LEDs), photodetectors, X-ray detection, and catalysis.
Refer to the following publications for examples of the work in this research direction:
J. Am. Chem. Soc. (2021). https://doi.org/10.1021/jacs.1c09106.
ACS Nano (2022). https://doi.org/10.1021/acsnano.1c07498.
J. Am. Chem. Soc. (2023). https://doi.org/10.1021/jacs.2c11896.
ACS Nano (2022). https://doi.org/10.1021/acsnano.2c06204.
Metal Halide Perovskites (MHPs)
MHPs are ionically-bound hybrid organic-inorganic semiconductors with excellent optical and electrical properties. What sets MHPs apart is their ability to be synthesized in solutions at low temperatures combined with their defect tolerance and long carrier diffusion lengths and times. Consequently, their generated charge carriers can persist for a significant duration, allowing efficient extraction at the devices' electrodes. This stands in contrast to traditional inorganic semiconductors, which necessitate laborious processes involving high manufacturing and energy costs as well as elevated greenhouse gas emissions, to achieve similar results.
Research in this direction spans crystal growth development and chemical tuning to the fundamental understanding of charge carriers and the fabrication of optoelectronic devices.
For examples of the work in this research direction, refer to the following publications:
Chem. Mater. (2019). https://doi.org/10.1021/acs.chemmater.9b01318.
J. Phys. Chem. Lett. (2020). https://doi.org/10.1021/acs.jpclett.0c02214.
J. Phys. Chem. Lett. (2021). https://doi.org/10.1021/acs.jpclett.0c03731.
Sci. Adv. 9, 33, eadg4417 (2023). https://doi.org/10.1126/sciadv.adg4417.
Crystal Growth and Engineering
We focus our efforts on crystal growth and engineering for two main reasons: (i) to obtain structural information on our newly developed materials to guide their designs, and (ii) to obtain high-quality, defect-free crystals for optimal device performance and the investigation of the materials' intrinsic properties.
Current work in this endeavor includes the development of novel crystallization techniques to allow the crystallization of previously non-crystallizable materials, control crystallized shapes, and engineer defect density in synthesized crystals.
Refer to the following publications for examples of the work in this research direction:
J. Am. Chem. Soc. (2021). https://doi.org/10.1021/jacs.1c09106.
Chem. Mater. (2019). https://doi.org/10.1021/acs.chemmater.9b01318.
Quantum-Dot and Nanoparticle Synthesis
In addition to producing materials in large forms, such as single crystals, we also focus on synthesizing small nanoparticles, such as quantum dots. These nanomaterials, with sizes of a few nanometers, can be solution-processed to produce optoelectronic devices at low cost.
Ongoing research in the lab includes synthesis development to obtain high-quality materials and post-synthesis treatment to tailor the properties of materials for various target applications.
For examples of the work in this research direction, refer to the following publications:
Adv. Mater. (2023). https://doi.org/10.1002/adma.202303528.
ACS Nano (2021). https://doi.org/10.1021/acsnano.1c09103.
Charge Carrier Physics
The flows of charge carriers in materials are crucial to the performance of resulting devices. Before they can be extracted at electrodes, generated charge carriers may fall into defect states or need to overcome potential barriers at grain boundaries, leading to efficiency loss. In our lab, we employ advanced optical and electrical characterization techniques to probe the dynamics of charge carriers in novel materials and devices. Additionally, we utilize temperature-dependent measurements as additional tools to uncover the underlying mechanisms of charge carrier dynamics.
See the following publications for examples of the work in this research direction:
J. Phys. Chem. Lett. (2020). https://doi.org/10.1021/acs.jpclett.0c02214.
Perovskite Solar Cells
By 2037, it is expected that 34% of Thailand's energy generation will be renewable. The installed solar cell capacity is predicted to rise by almost 400%, from 2,849 MW in 2023 to 12,139 MW in 2037. To support the country's energy shift, our group is working on new perovskite solar cell technology that can be as efficient as or even more efficient than silicon solar cells. Additionally, it is much more lightweight and can be coated on any surface.
Research in this direction spans from chemical tuning and purification of perovskite materials to device engineering. Our goal is to develop highly efficient and stable perovskite solar cells with the potential for commercialization.
X-ray Detection
The uses of X-rays span from medical imaging and radiotherapy to industrial defect monitoring and security inspection. However, X-rays are invisible and require materials to convert them into other forms of energy to be detectable.
In our lab, we develop novel materials that can efficiently convert X-rays into visible light or electrons, and construct screens and sensors to detect X-rays with high sensitivity and resolution.
(Work under submission. Please come back again soon to find an example of our work.)