Abstract
(CZTS) is a promising photovoltaic absorber material with earth-abundant and nontoxic elements. However, the detrimental native defects and secondary phases of CZTS will largely reduce the energy-conversion efficiencies. To understand the origin of these problems during the growth of CZTS, we investigated the kinetic processes on CZTS surface, using first-principles calculations. A surface Zn atom was found to occupy the Cu site near the surface easily due to a low reaction barrier, which may lead to a high concentration and a Zn-rich secondary phase. These -type defects may create deep electron traps near the interface and become detrimental to device performance. To reduce the population of and the Zn-rich secondary phase, we propose to use K as a surfactant to alter surface kinetic processes. Improvements on crystal quality and device performance based on this surfactant are consistent with early experimental observations.
- Received 9 July 2017
DOI:https://doi.org/10.1103/PhysRevMaterials.1.045403
©2017 American Physical Society