The electronic structure of the [Zn(S,O)/ZnS]/CuInS2 heterointerface – Impact of post-annealing

• DOI: 10.1016/j.cplett.2006.11.022
• Publication Date: 2006-11-16T02:28:15Z
• Authors: M. Bär; A. Ennaoui; J. Klaer; R. Sáez-Araoz; T. Kropp; L. Weinhardt; C. Heske; H.-W. Schock; Ch.-H. Fischer; M.C. Lux-Steiner
• Keywords: 0103 physical sciences; 01 natural sciences; 7. Clean energy

Abstract Recently, Cd-free wide-gap CuInS 2 -based ‘CIS’ thin film solar cells with a [Zn(S,O)/ZnS] bi-layer instead of a CdS buffer were developed, which (after post-annealing) showed comparable power conversion efficiencies as CdS-buffered references. To elucidate whether the heat treatment changes the electronic structure of the [Zn(S,O)/ZnS]/CIS heterointerface, which could explain the performance improvement, we have investigated corresponding structures by X-ray and UV photoelectron as well as optical spectroscopy before and after post-annealing. A heat-treatment-induced increase of the band bending in the CIS absorber could be identified, which correlates with an improved open circuit voltage of respective solar cells after post-annealing.