Abstracts Book - IMRC 2018

• SC4-P064
EFFECTS OF SECONDARY PHASES ON THE ELECTRO-OPTICAL
PROPERTIES OF THE Cu2SnS3 THIN FILMS DEPOSITED BY
ULTRASONIC SPRAY PYROLYSIS
Ignacio Estevez Espinoza 1 , Mauricio Ortega López 2 , Yasuhiro Matsumoto 2 , Octavio Estevez 3
1 Centro de Investigación y de Estudios Avanzados del IPN - CINVESTAV, Program of
Nanoscience and Nanotechnology, Mexico. 2 Centro de Investigación y de Estudios Avanzados
del IPN - CINVESTAV, Program of Nanoscience and Nanotechnology. Department of Electrical
Engineering (SEES), Mexico. 3 Universidad Nacional Autónoma de México, Instituto de Física,
Mexico.
The binary chalcogenides Cu2S-SnS2-ZnS leads to a number of promising
photovoltaic materials for low cost thin film-based solar cells technologies [1].
Kesterite CZTS being the most representative example because it posses
optoelectronic properties as those proposed for a high-performance absorber
material of thin film solar cells. Besides kesterite Cu2ZnSnS4, monoclinic Cu2SnS3
have emerged as promissory absorber materials because of it is intrinsically p-
type and has an optical band gap in the range of 0.9-1.4 eV [2]. It has been
proposed that, the relatively large variation of the energy gap in monoclinic
Cu2SnS3, could be due to its inherent polymorphism as it also crystallize in the
cubic structure, as well as presence of Cu3SnS8, SnS2 or CuxSy impurity phases
[3].
This work reports the synthesis and characterization of Cu2SnS3 thin films that
were deposited on glass substrates by ultrasonic spray pyrolysis at the substrate
temperature of 250, 300 and 350 °C, using aqueous solutions of CuCl2, SnCl2 and
(NH2)2CS (thiourea). The film physical properties were assessed by X-ray
diffraction, Raman spectroscopy, Electron microscopy (SEM), and UV-Vis
spectroscopy. For all experimental condition tested up to now, the obtained
films were multiphase and polycrystalline ones. The X-ray and Raman
characterizations revealed that they comprise monoclinic and cubic Cu2SnS3,
and traces of Cu4SnS8, they present a band gap in the range of 1.1 eV.
Future work is being addressed to improve the phase purity of sprayed films by
adjusting the chemical composition of starting solutions and selective chemical
etching.