Anomalous persistent photoconductivity in Cu2ZnSnS4 thin films and solar cells

• Temperature dependence of the PPC effect in CZTS is studied.
• An anomalous PPC effect in the CZTS samples is reported.
• Electrostatic local potential fluctuations explain the anomalous PPC effect.

A persistent photoconductivity effect (PPC) has been investigated in Cu2ZnSnS4 thin films and solar cells as a function of temperature. An anomalous increase of the PPC decay time with temperature was observed in all samples. The PPC decay time activation energy was found to increase when temperature rises above a crossover value, and also to grow with the increase of the sulfurization temperature and pressure. Both the anomalous behavior of the PPC decay time and the existence of two different activation energies are explained in terms of local potential fluctuations in the band edges of CZTS.