In the realm of energy research, a trio of scientists from the University of Paris-Saclay—Francesco Delodovici, Brahim Dkhil, and Charles Paillard—have been delving into the potential of two-dimensional (2D) ferroelectrics for next-generation optoelectronic and photovoltaic devices. Their recent study, published in the journal Physical Review Materials, sheds light on the size-effects on shift-current in the layered material CuInP$_2$S$_6$.
Two-dimensional ferroelectrics are materials that exhibit a spontaneous electric polarization which can be reversed by an external electric field. These materials are particularly interesting for the energy sector due to their unique properties. They possess an intrinsic lack of inversion symmetry, which allows them to exhibit the bulk photovoltaic effect (BPVE). This effect generates a photo-induced current using hot, non-thermalized photo-excited carriers, leading to efficient charge separation without the need for a p-n junction architecture. This makes them attractive for nanoscale energy harvesting.
The researchers focused on CuInP$_2$S$_6$, a ferroelectric material embedded between two graphene wafers. Previous studies have shown that this material can achieve short circuit photocurrent density values of up to milliamperes per square centimeter (mA/cm$^2$). The team’s work confirms that the enhanced BPVE in nanometer-thick CuInP$_2$S$_6$ is driven by relatively strong polarization and reduced dimensionality.
However, their research also reveals that the shift-current mechanism alone cannot fully account for these high conductivity values. This suggests that additional mechanisms may play a significant role in the enhanced performance of these materials. Furthermore, the study confirms the existence of a strong size effect, which drastically reduces the shift-conductivity response in the bulk limit. This finding aligns with experimental observations and has important implications for the practical application of these materials in the energy sector.
The practical applications of this research are significant for the energy industry. The use of 2D ferroelectrics could lead to more efficient and smaller-scale photovoltaic devices. The absence of a required p-n junction architecture simplifies the manufacturing process and could reduce costs. Moreover, the understanding of size-effects could guide the design of more efficient energy harvesting devices.
In summary, the work of Delodovici, Dkhil, and Paillard provides valuable insights into the behavior of 2D ferroelectrics and their potential for energy harvesting applications. Their findings contribute to the ongoing efforts to develop more efficient and cost-effective photovoltaic technologies. The research was published in the journal Physical Review Materials, a publication of the American Physical Society.
This article is based on research available at arXiv.