The development of van der Waals heterostructures for ultra-thin solar cell application

Although Si-based solar cells are highly efficient, stable and cost-per-watt is steadily decreasing, due to wafer-based solar cell structure it is not suitable for flexible and light-weight photovoltaic (PV) applications. High efficiency thin film solar cells such as Cu(In,Ga)Se2, CdTe, CHsNHsPbls have been demonstrated on flexible substrates, however each of the technology faces elemental abundance or toxicity issues. Earth-abundant thin film technology is highly desirable and many materials are being probed as potential PV absorbers. Among them, Sb2Se3 has been recognized and experimentally confirmed as promising PV material approaching 10% power conversion efficiency (PCE) recently. It was calculated that due to high absorption coefficient of Sb2Se3, maximum PCE can be achieved with absorber thickness of only 200-300 nm, which is suitable for ultra-thin solar cell applicafion. Because of high partial pressure and relatively low melting point, high quality Sb2Se3 films can be deposited at low substrate temperature therefore compatible with flexible substrates (e.g. polyimide).

In very thin absorbers, solar cell performance is strongly influenced by surface recombination velocity, which in turn depends on the quality of interfaces. It is known that van der Waals heterostructures can form very sharp and defects-free interfaces due to absence of dangling bonds of van der Waals surfaces. Sb2Se3 is a quasi-one-dimensional material that can form van der Waals heterostructure on other low dimensional substrates or on 3D if properly aligned. This PhD course is designated to explore and study the formation of van der Waals heterostructures based on Sb2Se3 with a goal to apply in ultra-thin solar cells.
For more information, please contact the theme supervisor R. Kondrotas.