Probing back contact interfaces and hole tunneling in Cu2ZnSnS4 solar cells using temperature-dependent J–V curves

The temperature-dependent behavior of the short-circuit current density J SC in Cu₂ZnSnS₄ (CZTS) thin-film and monograin layer solar cells was investigated over a wide temperature range (20–320 K) to clarify the properties of the back contact. All measured J SC ( T ) characteristics exhibited a distinct S-shaped dependence, indicating the presence of a transport barrier at the back interface. A modified Pöschl–Teller potential barrier model, which captures the temperature-dependent tunneling of holes, was successfully used to describe this behavior. Furthermore, spatial inhomogeneities at the back contact were identified, and the obtained data can be described by a Gaussian distribution of barrier heights across the interface.