Ternary Cu3BiY3 (Y = S, Se, and Te) for thin-film solar cells

• Very recently, Cu3BiS3 has been suggested as an alternative material for photovoltaic (PV) thin-film technologies. In this work, we analyze the electronic and optical properties of Cu3BiY 3 with the anion elements Y = S, Se, and Te, employing a first-principles approach within the density function theory. We find that the three Cu2BiY3 compounds have indirect band gaps and the gap energies are in the region of 1.2-1.7 eV. The energy dispersions of the lowest conduction bands are small, and therefore the direct gap energies are only ∼0.1 eV larger than the fundamental gap energies. The flat conduction bands are explained by the presence of localized Bi p-states in the band gap region. Flat energy dispersion implies a large optical absorption, and the calculations reveal that the absorption coefficient of Cu3BiY 3 is larger than 105 cm-1 for photon energies of ∼2.5 eV. The absorption is stronger than other Cu-S based materials like CuInS2 and Cu2ZnSnS4. Thereby, Cu 3BiY3 has the potential to be a suitable material in thin-film PV technologies.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

Keyword

Absorption co-efficient

Alternative materials

Density function theory

Electronic and optical properties

Energy dispersions

First-principles approaches

Thin-film solar cells

Thin-film technology

Calculations

Conduction bands

Copper compounds

Dispersions

Energy gap

Copper

Publication and Content Type

ref (subject category)

kon (subject category)