Structure, optical, electrical and electronic parameters of a new thin film composition for kesterite solar cell

Abstract

The work is devoted to the development of a new thin film composition for kesterite solar cell with the base Cu2ZnSnS4 (CZTS) layer obtained by the combination of two low-cost liquid methods, namely electrodeposition and Successive Ionic Layer Adsorption and Reaction (SILAR). The p-CZTS absorber is fabricated by the creation of the main Cu2ZnSnS4 layer through sulfurization of a stack of the electrodeposited Cu/Sn/Zn metal films. The pores in this main Cu2ZnSnS4 layer were filled by SILAR-deposited nanocrystalline kesterite layer. For a creation of semiconductor heterojunction n-ZnS/p-Cu2ZnSnS4 we prepared ZnS thin films by SILAR method. The work shows the results of analysis of diode characteristics of the developed ZnS/Cu2ZnSnS4 heterostructures (series resistance Rs, shunt resistance Rsh, ideality factor nd and the saturation current densities Jo). Other investigated electrical and electronic parameters obtained from the current-voltage (I-U) and capacitance-voltage (C-U) characteristics are the electrical resistivities ρCZTS and ρZnS, the ZnS/Cu2ZnSnS4 rectifying barrier Φ, the height φ of symmetrical double Schottky barriers in the grain boundary regions in the polycrystalline kesterite layers, the width of the electron depletion regions ω, the concentration of the fully ionized donor impurity Nd in n-ZnS and acceptor impurity Na in p-Cu2ZnSnS4, the density NSS of the surface states in the kesterite layers. Structure and optical properties of the ZnS films as such as of the individual kesterite layers and of their combination have been also researched.