Conductivity mechanisms and influence of the Cu/ Zn disorder on electronic properties of the powder Cu2ZnSn(S1-xSex)4 solid solutions

One of the major reasons for a recent stuck of the development of kesterite based photovoltaic devices is related to the problems in their open circuit voltage. Several limitations can be pointed out as a possible origin. In particular, for a case of Cu and Zn containing kesterite compounds, a lattice disorder connected to these cations is considered to bring in an important contribution to the limitations above. Extensive studies showed a significant influence of this disorder being an intrinsic property of kesterites to structural, optical and vibrational properties of the related materials. However, detailed investigations focused to the role of disorder in formation of the electrical properties of the kesterite materials are still lacking. In order to cover this gap, here is investigated resistivity of Cu₂ZnSn(S_1-xSe_x)₄ (CZTSSe) powder samples with x = 0.48 - 1.00 at temperatures between ~ 10 and 300 K. A detailed analysis of the measured data permits to establish various conductivity mechanisms within different temperature ranges, and to obtain a set of important macroscopic and microscopic electronic parameters. By itself, their dependence on x does not reveal any univocal behavior. In contrast, all the electronic parameters above exhibit a clear correlation with the order parameter Q. This is explained completely by a strong sensitivity of the electronic properties of CZTSSe to the Cu/Zn disorder.