POUDEU LAB
Copper metal chalcogenides (CMC)
Solar and thermoelectric energy conversions are two main approaches to generating renewable energy. However, many current conversion materials contain metals with limited supply, such as In, and restricted toxic elements, like As.
In this study, we generalized a formula that encompasses all the known high-performance CMC materials, which leads us to discover, characterize and evaluate numerous missing members in the CMC megaseries. Specifically, we target materials' common trait in superior photovoltaic materials like GaAs and CuInSe.
Through close collaborations with theorists, we expect to reveal new crystal structures beyond the known variations and accelerate our design process that will lead to vast numbers of highly-efficient CMCs.
Enhancing chemical stability and figure of merit for thermoelectrics
Although the thermal electric performance of Cu2-xSe is promising, chemical stability remains a key challenge for wide scale commercial use of the material. Its high ionic mobility brings chemical instability in forms of Se evaporation and Cu leakage.
Adding impurities is a well-established method to make Cu2-xSe (CS) more stable, namely by introducing nanoparticles and grain boundaries to block Cu ion migration. While localization of Cu and further reduce vibrational modes and thus thermal conductivity, we ensure impurity phases do not impede the high electrical conductivity simultaneously.
We designed CuInSe2 (CIS) nano-inclusions that have a similar sized Se sublattice to achieve Colosal zT values.
Dopant incorporated AgSe Solid Solutions
This project is focusing on developing novel semiconductor nanocomposites for optical applications and photovoltaic devices. We are using cation exchange reactions as the key strategy to achieve these goals. The compositions, structures, and optical properties of the nanocomposites can be modified.
Compared to most other published literatures on cation exchange synthesis, the two systems don’t require toxic and complex organic solvents, inert atmosphere, and heating, which provides a convenient way to optimize the performance of semiconductors for future research & development.