Cu2ZnSnS4 (CZTS) is a promising material for photovoltaic and thermoelectric applications. Issues with quaternary semiconductors include chemical disorder (e.g., Cu-Zn antisites) and disproportionation into secondary phases (e.g., ZnS and Cu2SnS3). To provide a reference for the pure kesterite structure, we report the vibrational spectra - including both infra-red and Raman intensities - from lattice-dynamics calculations using first-principles force constants. Three-phonon interactions are used to estimate phonon lifetimes (spectral linewidths) and thermal conductivity. CZTS exhibits a remarkably low lattice thermal conductivity, competitive with high-performance thermoelectric materials. Transition from the sulfide to selenide (Cu2ZnSnSe4) results in softening of the phonon modes and an increase in phonon lifetimes.
Bibliographical noteFunding Information:
We thank A. Togo for discussions on phonon theory and access to Phono3py. We acknowledge membership of the UK’s HPC Materials Chemistry Consortium, which is funded by EPSRC Grant No. EP/L000202. J.M.S. is funded by an EPSRC Programme Grant (No. EP/K004956/1). A.J.J. and S.K.W. are funded by the EPSRC Doctoral Training Centre in Sustainable Chemical Technologies (Nos. EP/G03768X/1 and EP/L016354/1). M.D. has received funding from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program under REA Grant Agreement No. 316488 (KESTCELLS). A.W. acknowledges support from the Royal Society and the ERC (Grant No. 277757).
All Science Journal Classification (ASJC) codes
- Materials Science(all)