Improving solar cell design is integral for improving energy consumption. Scientists have lately focused on making solar cells more efficient, flexible, and portable to enable their integration into everyday applications. Consequently, novel lightweight and flexible thin film solar cells have been developed. It is, however, not easy to combine efficiency with flexibility. For a material (usually a semiconductor) to be efficient, it must have a small “band gap” — the energy required to excite charge carriers for electrical conduction — and should absorb and convert a large portion of the sunlight into electricity. Till date, no such efficient absorber suitable for thin film solar cells has been developed.
In a new study published in Applied Materials and Interfaces, scientists from Korea addressed this issue and proposed a novel solution in the form of “antiperovskite” oxides, denoted as Ba4Pn2O, with Pn as stand-in for Arsenic (As) or Antimony (Sb). Using density functional theory calculations, scientists investigated various physical properties of the antiperovskite oxides and revealed that they exhibit spontaneous electric polarization, making them ferroelectric in nature. Prof. Youngho Kang from Incheon National University, who led the study, explains, In the minimum energy configuration of the Ba4Pn2O structure, we found that the O ions and the Ba ions are displaced from their original positions in opposite directions. These displacements gave rise to a non-zero electric polarization, a classic signature of ferroelectricity.”
Since the spontaneous polarization assists in the separation of eleat their band gaps are ideal for efficient sunlight absorption,ctron-hole pairs, this implied that antiperovskite oxides could efficiently extract charge carriers. In addition, the calculations showed th allowing even a very thin layer of Ba4Pn2O to yield substantial photocurrent.
Adapted and abridged from Source (Incheon National University. “A polarization-driven guide to making high-performance, versatile solar cells.” ScienceDaily. ScienceDaily, 4 January 2021.)
Original paper: Kang, Y. and Han, S., 2020. Antiperovskite oxides as promising candidates for high-performance ferroelectric photovoltaics: First-principles investigation on Ba4As2O and Ba4Sb2O. ACS Applied Materials & Interfaces, 12(39), pp.43798-43804.