Abstracts Book - IMRC 2018

• SC4-O017
AG INCORPORATION IN CZTS KESTERITE THIN FILMS FOR
PHOTOVOLTAIC APPLICATIONS
Raquel Garza Hernandez 1 , James T. Gibbon 2 , Vinod R. Dhanak 2 , Francisco Servando Aguirre
Tostado 1
1
Centro de Investigación en Materiales Avanzados, S.C., Laboratorio de Energías Alternas y
Electronica Flexible, Mexico. 2 Stephenson Institute for Renewable Energy, University of
Liverpool, Department of Physics, United Kingdom, Channel Islands & Isle of Man.
Cu2ZnSnS4 (CZTS) is a promising absorber layer material for thin film solar cells
because of the non-toxicity and abundance of the constituent elements. The
incorporation of extrinsic impurities such as Ag (to replace Cu) in the kesterite
structure offers the reduction of antisite defects via cation substitution and
improves the grain growth resulting in the increase of the conductivity and the
conversion efficiency. The effect of Ag incorporation on the kesterite (Cu1-
xAgx)2ZnSnS4 (CAZTS) thin film with 0 < x < 1.0 synthetized by spray pyrolysis has
been investigated. Energy-dispersive X-ray spectroscopy (EDS) was useful to
determine the chemical compositions of the different films. The crystalline
structure was analyzed by x-ray diffraction. The lattice constants a of the
kesterite-type CAZTS increase with Ag content (x) increasing. The main
vibrational mode A (anion vibrations) was kept in 337 cm -1 when x= 0-0.75 and
the vibrational mode B (cations displacement along c direction vibrations)
located on 366 cm -1 increases with the incorporation of silver. Band gaps of the
CAZTS thin films could be tuned 2.1 eV to 1.55 eV by changing the (Ag, Cu)
composition. The CAZTS films are composed for Cu + , Sn 4+ , Ag + , Zn 2+ and S 2-
determined by X-ray photoemission spectroscopy (XPS). The complete band
structure (valence and conduction band) was studied by XPS and inverse
photoemission spectroscopy (IPES). In addition, the potential of (Cu,Ag)2ZTS4
absorber layer for photovoltaic applications is discussed.
Acknowledgment:
The authors thank Dr. Tim Joyce Nanoinvestigation Centre at Liverpool for the
facilities to use the SEM and Dra. Laura Cabo-Fernandez SIRE for the access to
use Raman spectroscopic.
Keywords: electronic structure, CZTS, XPS
Presenting authors email: raquel.garza@cimav.edu.mx