A light-weight flexible monograin layer solar cell developed by TalTech researchers. (Professor Jüri Krustok) Flexible kesterite Cu2ZnSn(S,Se)4 (CZTSSe) has emerged in recent times owning to its great potential to be an abundant, low-cost, stable, and high-efficiency ‘green’ photovoltaic material that will be widely deployed with the bottom detrimental environmental impact.

A research group led by Prof. Meng Qingbo from the Institute of Physics (IOP) of the Chinese Academy of Science (CAS) and Prof. Xin Hao from Nanjing University of Posts and Telecommunications has reported 13.8% certified efficiency of emerging kesterite solar cells.

The study was published in Nature Energy on April 13.

Kesterite Cu2ZnSn(S, Se)4 (CZTSSe), as some of the competitive thin-film photovoltaic materials, exhibits attractive benefits reminiscent of earth-abundant elemental reserves, optimal bandgaps for photovoltaic (PV) technology, and high stability.

CZTSSe solar cells show an influence conversion efficiency (PCE) of 13% based on environmentally friendly solution systems. Nonetheless, a big open-circuit voltage deficit still restricts further device performance enhancement, primarily resulting from high deep-level defects within the CZTSSe absorber.

On this study, the researchers regulated the kinetic means of CZTSSe phase evolution by controlling positive chamber pressures.

Under positive chamber pressures, the phase evolution process could possibly be delayed to high temperatures (> 400°C).

Moreover, it might avoid complex phase evolution pathways and harmful secondary phases and achieve a high crystalline CZTSSe absorber with fewer defects.

The kesterite solar cell presented 14.1% PCE (total area) and a licensed 13.8% PCE (total area), which is the very best result to date.

The researchers applied modulating transient photovoltage/photocurrent measurement to research the carrier dynamics means of kesterite solar cells. They found that the majority defects were reduced by around one order of magnitude under positive chamber pressure, and the back interface contact property was also improved.

This study provides insights into the selenization mechanism of kesterite absorbers. It explores a recent way of kinetic regulation technique to simplify the phase evolution path to efficient kesterite solar cells.

Publication Referenced within the Article:

Jiazheng Zhou et al, Control of the phase evolution of kesterite by tuning of the selenium partial pressure for solar cells with 13.8% certified efficiency, Nature Energy (2023). DOI: 10.1038/s41560-023-01251-6

This text has been adapted from source material published by the Chinese Academy of Sciences.


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