2, Universidad Politécnica del Estado de Guerrero, Taxco del Álarcon, Guerrero, Mexico
3, Instituto de Ciencias Físicas-UNAM, Cuernavaca, Morelos, Mexico
4, Centro de Investigación en Ingeniería y Ciencias Aplicadas-UAEM, Cuernavaca, Morelos, Mexico
Antimony sulfide is a semiconductor material with interesting optoelectronic properties that have been used for its application as an absorber in the development of thin film- and semiconductor sensitized-solar cells, reaching power conversion efficiencies above of 5%. It has an n- or p-type conductivity, depending on the growth conditions and elements used for its doping, of 10-8-10-6 ohm-1 cm-1, an optical band gap of 1.5-1.8 eV, and a strong optical absorption in the UV-Vis region (>104 cm-1). However, it has been recognized that Sb2S3 films suffer from recombination of the photogenerated carriers in its surface as well as in the bulk due to their poor crystallinity and intrinsic defects. Different techniques have been reported for the growth of Sb2S3 thin films such as SILAR, electrodeposition, chemical bath deposition, thermal evaporation, atomic layer deposition, sputtering, and so on. Among these chemical bath deposition (CBD) offers the advantages of low-temperature deposition at atmospheric pressure with inexpensive infrastructure. In this way, different metallic/sulfur sources and complexing agents have been used for the growth of SB2S3 films by CBD. In spite of all these efforts, it has been obtained films with poor adherence and porous morphology that affect the performance of the solar cells. Then it is necessary to find new routes of synthesis and deposition of the Sb2S3 films in order to improve the quality and adherence of the films to obtain better photovoltaic devices.
In the present work, it is demonstrated the deposition of antimony sulfide thin films obtained by chemical bath deposition using tartaric acid as complexing agent. For the deposition, it is used antimony potassium tartrate and thioacetamide as sources of antimony and sulfur ions, respectively. The ph of the solution is adjusted to be in the range of 9-10 by using ammonium hydroxide. The chemical deposition is done at a constant temperature of 80°C during a period of time from 1 to 4 hours. The resulting thin films are homogeneous, compact, and well adherent to substrates coated with cadmium sulfide and zinc sulfide showing a yellow to orange color, depending on the thickness of the film. Furthermore, the as-deposited thin films showed an amorphous feature, which crystallize into the orthorhombic stibnite crystalline phase after they are treated in a nitrogen atmosphere. Analysis and results of SEM, XRD, UV-Vis spectroscopy, RAMAN and XPS are showed and discussed. Finally, it is shown the performance of these Sb2S3 thin films into the superstrate thin film SCs using cadmium sulfide as window layer.